Using ER Mapper

Using ER Mapper
ER Mapper
User’s Guide
September 2008
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Table of Contents
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Welcome to ER Mapper . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
How to use this manual . . . . . . . . . . . . . . . . . . . . . . . . 1
Request for user comments . . . . . . . . . . . . . . . . . . . . . 3
For information by email . . . . . . . . . . . . . . . . . . . . . . . 3
ER Mapper Web site . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
ER Mapper tutorial overview . . . . . . . . . . . . . . . . . . . . . . . . 5
Setting up practice images . . . . . . . . . . . . . . . . . . . . . 6
System setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typographical conventions . . . . . . . . . . . . . . . . . . . . . 8
Image processing with ER Mapper
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Image processing concepts . . . . . . . . . . . . . . . . . . . . . 9
Image processing applications . . . . . . . . . . . . . . . . . 10
Traditional image processing . . . . . . . . . . . . . . . . . . . 11
ER Mapper image processing . . . . . . . . . . . . . . . . . . . 11
Image processing tasks. . . . .
Data read/import . . . . . . . . . .
Image display . . . . . . . . . . . .
Image geocoding . . . . . . . . . .
Image mosaicing . . . . . . . . . .
Image enhancement . . . . . . . .
Dynamic Link layers . . . . . . . .
Map composition . . . . . . . . . . .
Data save/export and hardcopy
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ER Mapper algorithms . . . . . . . . . . . . . . . . . . . . . . . . 19
ER Mapper wizards . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ER Mapper user interface . . . . . . . . . . . . . . . . . . . . . . . . . 21
User interface components . . . . . . . . . .
Using mouse buttons . . . . . . . . . . . . . . . .
The ER Mapper main menu . . . . . . . . . . . .
Using ER Mapper toolbars . . . . . . . . . . . . .
Using dialog boxes . . . . . . . . . . . . . . . . . .
Using the File Chooser dialog boxes . . . . . .
Using the online help system . . . . . . . . . . .
Typing text in text fields . . . . . . . . . . . . . .
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Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1: Using menus and toolbars . . . . . . . . . . . . . . . . . . . 27
Move the ER Mapper main menu around the screen . . . . . . 27
Table of Contents
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Open a menu to display its commands, then close the menu
Select the Print command from the menu bar . . . . . . . . . .
Select the Print command from the Standard toolbar . . . . .
Display and hide a toolbar . . . . . . . . . . . . . . . . . . . . . . . .
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2: Opening windows and algorithms . . . . . . . . . . .
Open a new empty image window . . . . . . . . . . . . . . . .
Open and display an image processing algorithm . . . . . .
Use the toolbar to open a different processing algorithm .
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3: Resizing windows and zooming/panning . . . . . .
Move the image window on the screen . . . . . . . . . . . . .
Resize the image window . . . . . . . . . . . . . . . . . . . . . . .
Set the mouse pointer to Zoom mode . . . . . . . . . . . . . .
Zoom in and out of the image with the mouse . . . . . . . .
Set the mouse pointer to ZoomBox mode . . . . . . . . . . .
Zoom in (magnify) an area of the image with the mouse .
Set the mouse pointer to Hand mode . . . . . . . . . . . . . .
Pan (scroll) the image within the window with the mouse
Zoom back out to view the full image extents . . . . . . . .
Zoom and pan using buttons for predefined options . . . .
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4: Managing multiple image windows . . . . . . . . . . . . 34
Open a second image window . . . . . . . . . . . . . . . . . . . . . 34
Open and display a processing algorithm in the new window 34
Move the SPOT window to overlap with the Landsat window 34
Move one window in front of the other . . . . . . . . . . . . . . . 35
Select a window to be the active window . . . . . . . . . . . . . . 35
Close both image windows . . . . . . . . . . . . . . . . . . . . . . . . 36
Handling images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
About the algorithms concept . . . . . . . . . . . . . . . . . . 37
What is an algorithm? . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
The Algorithm window . . . . . . . . . . . . . . . . . . . . . . . 37
The Process Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 39
1: Loading and displaying images . . . . . . . . . . . . .
Open an image window and the Algorithm window . . . . .
Load a raster image into the Pseudocolor layer . . . . . . .
Select and display different bands in the Landsat image .
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2: Processing the image . . . . . . . . . . . . . . . . . . . . . . 43
Load a vegetation index formula into the layer . . . . . . . . . . 43
Adjust the image contrast . . . . . . . . . . . . . . . . . . . . . . . . 43
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3: Labeling and saving the algorithm . . . . . . . . . . .
Enter a description for the Pseudocolor layer . . . . . . . . .
Enter a description for the surface . . . . . . . . . . . . . . . .
Enter a description for the entire algorithm . . . . . . . . . .
Save the processing steps to an algorithm file on disk . . .
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4: Reloading and viewing the algorithm . . . . . . . . .
Open a second image window . . . . . . . . . . . . . . . . . . .
Open the processing algorithm you created earlier . . . . .
Add comments to the algorithm . . . . . . . . . . . . . . . . . .
View the algorithm comments . . . . . . . . . . . . . . . . . . .
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Table of Contents
5: Viewing the image in 3D perspective . . . . . . . . .
About 3D perspective viewing . . . . . . . . . . . . . . . . . . .
Display the vegetation image in brown and green . . . . . .
Add a Height layer to the algorithm . . . . . . . . . . . . . . .
Load a digital elevation image into the Height layer . . . .
Select 3D perspective View Mode to view the image in 3D
Turn off the 3D lighting option . . . . . . . . . . . . . . . . . . .
Change the perspective viewing angle . . . . . . . . . . . . . .
Select 2D View Mode to view the image in 2D again . . . .
Close the image and Algorithm dialog windows . . . . . . .
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Working with data layers . . . . . . . . . . . . . . . . . . . . . . . . . 51
About data layers . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Layer controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
About color modes . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Color Mode options (in Surface Tab) . . . . . . . . . . . . . . . . . 52
About data layers . . . . . . . . . . . . . . . . .
Raster layer types . . . . . . . . . . . . . . . . . . .
Vector layer types . . . . . . . . . . . . . . . . . . .
Selecting and Modifying Data Layers . . . . . .
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Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 54
1: Turning layers on and off . . . . . . . . . . . . . . . . .
Open an image window and display a mosaic algorithm .
Open the Algorithm window to view the data layers . . . .
Turn overlays off to exclude them from processing . . . . .
Turn overlays on to include them in processing . . . . . . .
Change the Color Mode to see how it affects layers . . . .
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2: Loading data into layers . . . . . . . . . .
Open a Red Green Blue (RGB) algorithm . . .
Load a new image into all three layers . . . .
Load a new image into all three layers . . . .
Load a new image into only one layer . . . . .
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3: Adding and changing layers . . . . . . . . . . . . . . . . . . 60
Open a new RGB algorithm . . . . . . . . . . . . . . . . . . . . . . . 60
Change the order of layers using buttons . . . . . . . . . . . . . 61
Change the order of layers by dragging . . . . . . . . . . . . . . . 61
Delete the Blue and Green layers . . . . . . . . . . . . . . . . . . . 61
Restore the Green layer by adding one and loading the image .
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Restore the Blue layer by duplicating the Green layer . . . . . 62
Adjust the transforms of the Green and Blue layers . . . . . . 63
Close all image windows and dialog boxes . . . . . . . . . . . . . 64
Viewing image data values . . . . . . . . . . . . . . . . . . . . . . . . 65
About viewing data values . . . . . . . . . . . . . . . . . . . . 65
Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 65
1: Viewing values and signatures . . . . .
Open and display an RGB algorithm . . . . . .
View cell values in the image for all bands . .
View a neighborhood of cell values . . . . . . .
Table of Contents
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View a signature of cell values for various features . . . . . . . 67
View an average signature for a feature . . . . . . . . . . . . . . 68
2: Viewing locations and distances . . . . . . . . . . . . . . 68
View geographic coordinates in the image . . . . . . . . . . . . . 68
View distances between points in the image . . . . . . . . . . . 69
3: Viewing traverse profiles . . . . . . . . .
Set up to draw traverse profile lines . . . . . .
Draw a traverse line on the image . . . . . . .
View profiles for 3 image dataset bands . . .
Draw a second traverse line on the image . .
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4: Viewing image scattergrams . . . . . . . . . . . . . . . . . 72
Open a Scattergram dialog box . . . . . . . . . . . . . . . . . . . . 72
Change the image band combination . . . . . . . . . . . . . . . . 73
Change the axis limits to “zoom in” on part of the scattergram
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Close all image windows and dialog boxes . . . . . . . . . . . . . 75
Enhancing image contrast . . . . . . . . . . . . . . . . . . . . . . . . 77
About contrast enhancement . . . . . . . . .
Displaying images with a color lookup table .
Displaying images in RGB . . . . . . . . . . . . .
The Transform buttons . . . . . . . . . . . . . . .
The Transform dialog box . . . . . . . . . . . . .
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Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . .
Load and display an image in grayscale . . . . . . . . . . . . .
View the histogram for the SPOT Pan image . . . . . . . . .
View the data values inside the histogram window . . . . .
Turn on a coordinate grid . . . . . . . . . . . . . . . . . . . . . .
Close the Transform dialog and the Algorithm window . .
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2: Using linear transforms . . . . . . . . . . . . . . . . . . .
Reopen the Transform dialog from the toolbar . . . . . . . .
Apply a linear lightening effect to the image . . . . . . . . .
Apply a linear darkening effect to the image . . . . . . . . .
Apply a linear contrast stretch to increase image contrast
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3: Highlighting features . . . . . . . . . . . . . . . . . . . . . . 84
Adjust the transform to maximize contrast in the ocean areas .
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Adjust the transform to maximize contrast in the land areas 86
4: Modifying data and display ranges . . . . . . . . . .
Use Limits to Actual to set the X axis data range . . . . . .
Set the input limits to 99% of the histogram range . . . . .
Set exact input limits to highlight the ocean data range .
Set exact output limits to use specific lookup table colors
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5: Using automatic transform options . . . . . . . . . . . . 88
Reset the image display to grayscale and the default transform
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Apply an autoclip transform to the data . . . . . . . . . . . . . . . 89
Apply a Histogram equalize transform to the data . . . . . . . 90
Apply a Gaussian equalize transform to the data . . . . . . . . 90
Apply a level slice transform to the data . . . . . . . . . . . . . . 91
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Table of Contents
Apply a Logarithmic and Exponential transforms to the data
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6: Working with multiple transforms . . . . . . . . . . .
Open the Algorithm window . . . . . . . . . . . . . . . . . . . . .
Apply a 99% autoclip transform to the data . . . . . . . . . .
Insert a second transform before the current one . . . . . .
Delete the new transform from the process stream . . . . .
Append a second transform after the current one . . . . . .
Specify Gaussian equalization for the new transform . . . .
Move to the previous transform and histogram . . . . . . .
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7: Using automatic contrast stretching . . . . . . . . .
Open an RGB algorithm . . . . . . . . . . . . . . . . . . . . . . . .
Change the band combination to RGB=321 . . . . . . . . . .
Use the Refresh Image button to enhance the contrast . .
View a different image and bands . . . . . . . . . . . . . . . . .
Close all image windows and dialog boxes . . . . . . . . . . .
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A quick example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Sunshading and colordraping . . . . . . . . . . . . . . . . . . 97
Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 97
1: Viewing sunshaded magnetics data . . . . . . . . . . . . 97
Open a magnetics image and view it colordraped and in 3D . 98
Apply sunshading to your image . . . . . . . . . . . . . . . . . . . . 99
2: Colordraping radiometrics over the magnetics data . .
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Mosaicing, balancing and compression . . . . . . . . . . . . . . . 103
About creating mosaics . . . . . . . . . . . . . . . . . . . . . . 103
ER Mapper mosaic capabilities . . . . . . . . . . . . . . . . . . . . 103
Image display priority . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . 104
1: Creating a grayscale image mosaic . . . . . . . . . .
Select files to display and mosaic . . . . . . . . . . . . . . . . .
Select file types to mosaic . . . . . . . . . . . . . . . . . . . . . .
Select mosaic properties . . . . . . . . . . . . . . . . . . . . . . .
Select display method . . . . . . . . . . . . . . . . . . . . . . . . .
Select display band . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mosaic and display the images . . . . . . . . . . . . . . . . . . .
Turn the center image on and off . . . . . . . . . . . . . . . . .
Zoom in to the geographic extents of any image dataset .
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2: Creating an RGB image mosaic . . . . . . . . . . . . . . 110
Change the image display method . . . . . . . . . . . . . . . . . 110
3: Color balancing the mosaic . . . . . . . . . . . . . . . .
Open the Image Balancing Wizard for Airphotos . . . . . . .
Analyze images for balancing . . . . . . . . . . . . . . . . . . . .
Select how to balance the images . . . . . . . . . . . . . . . . .
Color matching the image . . . . . . . . . . . . . . . . . . . . . .
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4: Compressing the mosaic . . . . . . . . . . . . . . . . . . . 115
Open the Image Compression Wizard . . . . . . . . . . . . . . . 115
Select compression ratio . . . . . . . . . . . . . . . . . . . . . . . . 117
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View the compressed image . . . . . . . . . . . . . . . . . . . . . . 119
Close the image window and Algorithm dialog . . . . . . . . . 119
5: Creating a grayscale image mosaic manually . . .
Open a new image window and the Algorithm dialog . . . .
Load a dataset into the Pseudo layer . . . . . . . . . . . . . . .
Create a mosaic by adding a second adjacent dataset . . .
Zoom out to view the extents of both images . . . . . . . . .
Add a third dataset to the mosaic . . . . . . . . . . . . . . . . .
Turn the center image on and off . . . . . . . . . . . . . . . . .
Brighten the center image to enhance the seam lines . . .
Change the display priority of the center image . . . . . . .
Zoom in to the geographic extents of any image dataset .
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6: Creating an RGB image mosaic manually . . . . . .
Load the template RGB algorithm . . . . . . . . . . . . . . . . .
Load an ADAR image into the RGB layers . . . . . . . . . . .
Add a second group of new RGB layers . . . . . . . . . . . . .
Load an adjacent ADAR dataset into the new RGB layers .
Select bands for the new Green and Blue layers . . . . . . .
Creating multiple sets of RGB layers . . . . . . . . . . . . . . .
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7: Using histogram matching . . . . . . . .
Open the Transform dialog box . . . . . . . . .
Histogram match the Red layers . . . . . . . . .
Histogram match the Green layers . . . . . . .
Histogram match the Blue layers . . . . . . . .
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8: Using mosaic seam feathering . . . . . . .
Load the mosaic of four datasets algorithm . .
Zoom in on a seam line between two datasets
Turn on the mosaic feathering option . . . . . .
Close the image window and Algorithm dialog
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Composing maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
About map composition . . . . . . . . . . . . . . . . . . . . . . 133
Hands-on exercises . . . . . . . . . . . . . . . . . . . . . . . . . 134
1: Setting up the page . . . . . . . . . . . . . . . . . . . . . .
Display a Landsat/SPOT IHS merge algorithm . . . . . . . .
Open the Page Setup dialog box . . . . . . . . . . . . . . . . . .
Specify how the page or map can be scaled . . . . . . . . . .
Snap Shot the current algorithm extents . . . . . . . . . . . .
Specify the output page size . . . . . . . . . . . . . . . . . . . .
Specify the output map scale . . . . . . . . . . . . . . . . . . . .
Position the contents on the page . . . . . . . . . . . . . . . . .
Set the background color to white . . . . . . . . . . . . . . . .
Save the algorithm with the Page Setup parameters . . . .
Open the Page Setup wizard . . . . . . . . . . . . . . . . . . . .
Set the background color to white . . . . . . . . . . . . . . . .
Set the contents extents . . . . . . . . . . . . . . . . . . . . . . .
Set autovary parameter . . . . . . . . . . . . . . . . . . . . . . .
Specify the output page size . . . . . . . . . . . . . . . . . . . .
Position the contents on the page . . . . . . . . . . . . . . . . .
Specify the output map scale . . . . . . . . . . . . . . . . . . . .
Add a vector layer to overlay a road network file . . . . . .
viii
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Save the algorithm with the Page Setup parameters . . . . . 141
2: Defining annotation objects . . . . . . . . . . . . . . .
Open the Geoposition dialog box . . . . . . . . . . . . . . . . .
Zoom to the Page Extents and Page Contents . . . . . . . .
Add a vector layer to overlay a road network file . . . . . .
Add a second vector layer for map annotation . . . . . . . .
Draw two polylines on the image . . . . . . . . . . . . . . . . .
Modify the attributes of the polylines . . . . . . . . . . . . . .
Draw a shaded polygon around the island . . . . . . . . . . .
Draw a shaded oval and move and resize it . . . . . . . . . .
Draw, modify and position text strings . . . . . . . . . . . . .
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3: Defining map objects . . . . . . . . . . . . . . . . . . . .
Zoom to the Page Extents to view the entire map page . .
Layout the types and positions of map objects . . . . . . . .
Add a scale bar centered below the image . . . . . . . . . . .
Add a compass north arrow on the lower-right . . . . . . . .
Add a company logo on the lower-left . . . . . . . . . . . . . .
Add a main title above the image . . . . . . . . . . . . . . . . .
Define an Eastings/Northings grid over the image . . . . .
Adjust the size or position of any object . . . . . . . . . . . .
Save the annotation/map composition file to disk . . . . . .
Save the algorithm to update the changes . . . . . . . . . . .
Additional features of Map Composition . . . . . . . . . . . . .
Page Relative and Map Unit Relative map objects . . . . . .
Printing your map . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Close all image windows and dialog boxes . . . . . . . . . . .
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Canadian National Transformation Version 2 (NTv2)
Grid-based Datum Shift Support . . . . . . . . . . . . . . . 154
NTv2 Support for other Regions . . . . . . . . . . . . . . . . . . . 155
Modifying Existing Datums Changes to Use NTv2 . . . . . . . 155
Adding New NTv2 Transformations to ER Mapper . . . . . . . 156
Quick reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
ER Mapper menus and toolbars
. . . . . . . . . . . . . . . . . . . 161
Menus . . . . . . . . .
File . . . . . . . . . .
Edit . . . . . . . . . .
View . . . . . . . . .
Toolbars . . . . . .
Process . . . . . . .
Utilities . . . . . . .
Windows . . . . . .
Help . . . . . . . . .
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Toolbars . . . . . . . . . . . . . . . . . . . . . . . .
Button logic for creating algorithms . . . . . .
Standard . . . . . . . . . . . . . . . . . . . . . . . . .
Common Functions . . . . . . . . . . . . . . . . . .
Annotation . . . . . . . . . . . . . . . . . . . . . . . .
Aster . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Batch Processing . . . . . . . . . . . . . . . . . . .
Classification . . . . . . . . . . . . . . . . . . . . . .
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ix
Compression . . . .
DEM . . . . . . . . . .
ESG Color Enhance
ESG QuickStretch .
ESG Utilities . . . . .
Forestry . . . . . . . .
Geophysics . . . . .
GIS . . . . . . . . . . .
Minerals . . . . . . .
Oil and Gas . . . . .
Radar Common . .
Radar Filters . . . .
Remote Sensing . .
Web Publishing . . .
Wizards . . . . . . . .
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ER Mapper algorithms, filters and formulae . . . . . . . . . . . . 183
Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Building Algorithms in ER Mapper . . . . . . . . . . . . . . . . . . 183
Using Algorithms as Templates . . . . . . . . . . . . . . . . . . . . 184
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Formulae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
ER Mapper Wizards . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
3-D Algorithm Wizard . . . . . . . . . . . . . . . . . . . . . . . 187
ASTER Data Processing Wizard . . . . . . . . . . . . . . . . 188
Processing modules . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Change Projection/Datum/Cell Size Wizard . . . . . . . 193
Common Geophysical Images Wizard . . . . . . . . . . . . 193
Contact Sheet Wizard
Preparing the images
Running the wizard . .
Restrictions . . . . . . .
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Contouring Wizard . . . . . . . . . . . . . . . . . . . . . . . . . 196
ESG Wizards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Gridding Wizard . . . . . . . . .
Project File . . . . . . . . . . . . . .
Input sources . . . . . . . . . . . .
Output gridded image . . . . . .
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HDF Import Wizard . . . . . . . . . . . . . . . . . . . . . . . . . 201
Image Balancing Wizard . . . . . . . . . . . . . . . . . . . . . 204
Image Compression Wizard . . . . . . . . . . . . . . . . . . . 206
Image Display and Mosaic Wizard . . . . . . . . . . . . . . 209
Land Applications Wizard (LAW) . . . . . . . . . . . . . . . 211
Processing modules . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Landsat TM Wizard . . . . . . . . . . . . . . . . . . . . . . . . . 213
Landsat Web Publishing Wizard . . . . . . . . . . . . . . . . 213
x
Table of Contents
Preparing to use the wizard . . . . . . . . . . . . . . . . . . . . . . 214
Local Council Applications Wizard . . . . . . . . . . . . . . 215
Available options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Magnetics Fourier Wizard . . . . . . . . . . . . . . . . . . . . 217
Map Collar Wizard . . . . . . . . . . . . . . . . . . . . . . . . . . 218
MapInfo .tab File Wizard . . . . . . . . . . . . . . . . . . . . . 219
About .tab files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Mineral Exploration Wizard (MEW) . . . . . . . . . . . . . 220
Processing modules . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Ortho and Geocoding Wizard . . . . . . . . . . . . . . . . . . 222
Page Setup Wizard . . . . . . . . . . . . . . . . . . . . . . . . . 225
Other wizards . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HGT Batch Import Wizard . . . . . . . . . . . . . . . . . . . . . .
Image subset Wizard . . . . . . . . . . . . . . . . . . . . . . . . .
Machine Configuration Report Wizard . . . . . . . . . . . . . .
Large Mosaic Wizard . . . . . . . . . . . . . . . . . . . . . . . . . .
Using batch scripts and designing your own wizards . . . .
. 227
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Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Supervised classification . . . . . . . . . . . . . . . . . . . . . 231
To carry out a supervised classification: . . . . . . . . . . . . . 231
Unsupervised Classification . . . . . . . . . . . . . . . . . . . 232
To carry out unsupervised classification . . . . . . . . . . . . . . 232
To display the classified data . . . . . . . . . . . . . . . . . . . . . 232
Dynamic Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
To add a Dynamic Link layer to an algorithm . . . . . . . . . . 235
Fourier processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
To transform an image to or from the frequency domain . . 237
To apply a filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Geolinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Geolink (Screen, Window
None . . . . . . . . . . . . . . .
Windows . . . . . . . . . . . .
Screen . . . . . . . . . . . . .
To Geolink windows . . . .
or None)
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Geolink (Overview Zoom and Roam) . . .
Overview Zoom . . . . . . . . . . . . . . . . . . . .
Roam . . . . . . . . . . . . . . . . . . . . . . . . . . .
To Geolink windows . . . . . . . . . . . . . . . . .
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Importing/Exporting raster and vector images . . . . . . . . . . 241
Importing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Exporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Table of Contents
xi
Map projections supported by ER Mapper . . . . . . . . . . . . . 243
Datum definition files . . . . . . . . . . . . . . . . . . . . . . . 243
Supplied projections and projection definition files . 243
Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
To produce a hardcopy image
. . . . . . . . . . . . . . . . . . . . 247
Print setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
To edit print settings (Hardcopy Control Files) . . . . . . . . . 248
To edit print settings (PC Printing) . . . . . . . . . . . . . . . . . 248
Virtual datasets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
To create a virtual dataset . . . . . . . . . . . . . . . . . . . . . . . 251
To use a virtual dataset: . . . . . . . . . . . . . . . . . . . . . . . . 251
ER Mapper documentation . . . . . . . . . . . . . . . . . . . . . . . 253
Introduction . . . . . . . . . . . . .
ER Mapper Release Notes . . . .
ER Mapper Airphoto Tutorial . . .
ER Mapper Applications . . . . . .
Customizing ER Mapper . . . . . .
ER Mapper Installation . . . . . .
ER Mapper Tutorial . . . . . . . . .
ER Mapper User Guide . . . . . . .
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Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
xii
Table of Contents
Welcome to ER Mapper
ER Mapper is the most advanced and powerful geographic image
processing software product available today. The added features and
functionality in this release makes the package easier to use while
delivering powerful tools to users at all skill levels.
ER Mapper runs on PCs running Windows XP and Windows XP x64.
Using ER Mapper you can display and enhance raster data, display
and edit vector data and link with data from Geographic and Land
Information Systems, Database Management Systems or virtually
any other source.
You can use ER Mapper to prepare your imagery for any application.
Its strengths are its easy-to-use interface and the many wizards and
other tools that it provides to make many complex tasks simple. It
also eliminates the drudgery of repetitive tasks by automating the
steps. ER Mapper natively supports most commonly used image and
data formats and has a continuously updated database of datums
and projections from around the world.
The traditional strengths of ER Mapper lie in the ease with which you
can process airphoto and satellite data. What were once held to be
complex tasks, e.g., orthorectification, image balancing, gridding
and contouring, geocoding and analyses of imagery, can all be
carried out by a user with just a basic understanding of image
processing techniques and ER Mapper.
Image visualization and presentation takes on a whole new meaning
with the ease with which you can create, modify and display maps,
3D flythrough and perspective views and classified images. You can
then compress these images using ECW and serve them over the
Internet with the Image Web Server.
To make it all fit together, ER Mapper offers easy integration with
GIS, database and other software allowing you to view data from
other applications in ER Mapper. You can also view ER Mapper/ECW
images in other applications with the help of free plug-ins provided
with ER Mapper.
This document helps you with getting started with image processing
using ER Mapper’s extensive features. A tutorial section is included
which takes you through the basics of ER Mapper using hands-on
exercises. The document also details the strengths and benefits of
using ER Mapper including descriptions of the many useful wizards,
algorithms, formulae and filters that are included to make your
image processing tasks simple.
How to use this
manual
Welcome to ER Mapper
Use this manual to assist you with using your product. A basic
tutorial, with hands-on exercises, is included to help you to quickly
get acquainted with the basic concepts of image processing using
ER Mapper.
1
This manual has mainly been created using material from the online
Help manuals provided with ER Mapper. It is not provided as an
online manual, but it provides extensive references to additional
topics in the online manuals. If you are an experienced ER Mapper
user and are looking for advanced topics, please refer to the online
help manuals for detailed information.
References to online Help manuals help you quickly navigate to the
right section in the online manuals. For example, where a reference
states “Refer to Part Two - Algorithms and Images, “Image Display
and Mosaic Wizard” of the ER Mapper User Guide for more
information, click on Help in the main menu, and choose User
Guide. This will open the online Help document to its contents page
where you can quickly navigate to Part Two - Algorithms and Images
and from there to the section on Image Display and Mosaic Wizard.
To install ER Mapper:
2
•
Follow the instructions in the ERDAS IMAGINE Configuration
Guide for Windows.
•
Next, refer to the ER Mapper Configuration Guide for
configuration information. You also learn how to install and
configure a digitizer.
•
Following that, go through “Getting started with ER Mapper” to
learn the basic concepts necessary to effectively use ER Mapper.
•
Lastly, find detailed concepts in the online ER Mapper Tutorial
manual. You should have a general understanding of how to use
your PC operating system. The “Working with ER Mapper” section
gives you an overview of the various ready-made features in
ER Mapper which will help to streamline your image processing
tasks. These include a description of the data formats which you
can directly open in ER Mapper, a description of the tools and
menus provided with the program and also quick references to
useful wizards, algorithms, formulae and filters which you can
use as ‘templates’.
Welcome to ER Mapper
Request for user
comments
We are interested in hearing from you. Although we thoroughly test
the software we do sometimes miss things. Please let us know if you
find something that could be improved. Sometimes we don’t hear
about problems because everyone assumes someone else has told
us! Positive feedback is also welcome.
Asia Pacific Region
ER Mapper
2 Abbotsford Street,
West Leederville
Western Australia 6007
Telephone: +61 8 9388-2900
Facsimile: +61 8 9388-2901
[email protected]
We will do our best to incorporate any feedback into future versions
of the software and documentation.
For information by
email
If you want to receive the latest information about Earth Resource
Mapping products, send an email message to:
[email protected]
In the body of the email type “subscribe ermapper Firstname
Lastname” where “Firstname Lastname” is your full name.
If there are several ER Mapper users at your site, ask your system
administrator to set up a mailing alias and send us the address.
ER Mapper Web
site
Information and support is also available via the ER Mapper Web
site:
Help
All ER Mapper manuals (save this one) are available online. They
have extensive index and contents facilities. The online help also
features context-sensitive lookup and up-to-date information on the
latest features and developments.
http://www.ermapper.com
The following manuals can be accessed from the ER Mapper menu
bar (click on Help and select the required manual from the dropdown list):
Welcome to ER Mapper
•
Release Notes
•
Airphoto Tutorial
3
•
Applications
•
Customizing
•
Tutorial
•
User Guide
For a description of the contents of each of these manuals,
please refer to the “ER Mapper documentation” chapter.
4
Welcome to ER Mapper
ER Mapper tutorial overview
This section is intended to get you started learning and using
ER Mapper. It provides simple step-by-step lessons that give you
hands-on practice using the basic features of the software.
For information on using more advanced features refer to the
online ER Mapper Tutorial. Please read the following important
information before beginning.
•
Chapter contents.
•
Setting up practice images.
•
Typographical conventions used in this document.
This tutorial is not intended to cover all ER Mapper functionality
in depth. Please refer to the ER Mapper User Guide and other
manuals for more detailed information as needed.
The hands-on exercises in this workbook require that the sample
images and algorithms supplied on the ER Mapper CD-ROM be
installed and accessible. Please refer to “Setting up practice
images” for more information.
The chapters in this section give you hands-on experience using the
ER Mapper software through a series of specially designed lessons.
Most lessons have two basic sections:
•
an overview of key concepts.
•
a series of step-by-step hands-on exercises.
It is recommended that you start at the beginning and proceed
through the chapters in order because the later chapters build on
concepts learned in earlier ones. However, each chapter is
independent of the others, so you can refer to a specific chapter at
any time for a quick procedural overview or refresher course.
The emphasis of this tutorial is on learning and using the ER Mapper
software, not on teaching remote sensing concepts and applications.
For more detailed information on the principles of image
processing or remote sensing for specific applications, please
refer to the ER Mapper Applications Manual, or any of the
text books available.
ER Mapper tutorial overview
5
Setting up
practice images
The exercises in this manual assume that ER Mapper is installed and
licensed, and that you will use the default ER Mapper ‘tutorial’
directory to save sample processing algorithms and other files during
the lessons. In addition, some chapters require that copies of the
ER Mapper sample image files be placed into the ‘tutorial’ directory.
System setup
This section describes the alternate steps needed to set up your
system to perform the hands-on exercises in this manual. There are
two tasks:
•
Installation of example “tutorial” image and algorithm files.
•
Copying files for supervised classification and rectification
exercises.
Installation of example images and algorithms
All of the hands-on exercises in this workbook require you to access
sample images and algorithms supplied on the ER Mapper CD-ROM.
The “Full” installation option installs ER Mapper with all the example
directories and files. If you want to conserve hard drive space, you
can select the “Typical” option which installs only the directories and
files required to do the hands-on exercises. The “Compact” option
does not install any of the required files or directories and thus
precludes you from doing the hands-on exercises.
See the “Installing ER Mapper” chapter for more information.
It is preferable to select either the “Typical” or “Full” installation
option to ensure that the correct files and directories are installed. If
you choose the “Custom” installation option, you must select at least
the following example directories for installation.
Application Examples
•
Airphoto
•
Mineral_Exploration
•
Oil_and_Gas_Exploration
•
World_Topography
•
Land_Information
Data Type Examples
6
•
Digital_Elevation
•
Ers1
•
Landsat_MSS
ER Mapper tutorial overview
•
Landsat_TM
•
SPOT_Panchromatic
•
SPOT_xs
Functions and Features Examples
•
3D
•
Classification
•
Data_Fusion
•
Data_Mosaic
•
Geocoding
•
Gridding
Miscellaneous
•
Templates
•
Test Patterns
Supervised Classification and Image Rectification
The exercises for Supervised Classification and Image Rectification
require a copy of the image "Landsat_MSS_notwarped" under the
name "Landsat_practice" in ER Mapper's 'tutorial' directory. (The
'tutorial' directory is created automatically during the ER Mapper
installation.) Follow these steps to create a copy of the header file
and data file.
You must have read and write access to the practice image. Set
the file permissions appropriately if needed.
Copying files for Windows installations
1. Use Windows Explorer to copy and rename the following files in the
'examples\Shared_Data' directory to the
'examples\Miscellaneous\Tutorial' directory as indicated:
ER Mapper tutorial overview
•
Shared_Data\Landsat_MSS_notwarped.ers copy to
Miscellaneous\Tutorial\Landsat_practice.ers
•
Shared_Data\Landsat_MSS_notwarped copy to
Miscellaneous\Tutorial\Landsat_practice
7
Typographical
conventions
The following typographical conventions are used throughout this
document:
•
ER Mapper menus, button names and dialog box names are
printed in boldface Helvetica type, for example:
“Select Print from the File menu to open the Print dialog box.”
•
Where you are asked to click the mouse on an icon button in the
user interface, both the button and its formal name are indicated
in the text. For example:
“Click on the Edit Transform Limits
•
8
button.”
Text to be typed in a dialog box text field is shown in boldface
Courier typeface, for example: “Type vegetation_index in the
text field.”
ER Mapper tutorial overview
Image processing with ER Mapper
This chapter provides a brief overview of general image processing
concepts, the types of data you can process and typical ER Mapper
applications in the earth sciences. It also provides an overview of
how the ER Mapper software works and advantages it provides over
other image processing systems.
If you are already familiar with these concepts and want to get
started with the exercises which will teach you how to use
ER Mapper, go straight to the “ER Mapper user interface”
chapter.
Image processing
concepts
The term digital image processing refers to the use of a computer to
manipulate image data stored in a digital format. The goal of image
processing for earth science applications is to enhance geographic
data in digital format so as to make it more meaningful to the user,
extract quantitative information and solve problems.
A digital image is stored as a two-dimensional array (or grid) of small
areas called pixels (picture elements), and each pixel corresponds
spatially to an area on the earth’s surface. This array or grid
structure is also called a raster, so image data is often referred to as
raster data. The raster data is arranged in horizontal rows called
lines, and vertical columns called samples. Each pixel in the image
raster is represented by a digital number (or DN).
columns
(samples)
rows
(lines)
Image processing with ER Mapper
individual cells or
pixels in raster array
9
These image DNs can represent many different types of data
depending on the data source. For satellite data such as Landsat and
SPOT, the DNs represent the intensity of reflected light in the visible,
infrared or other wavelengths. For imaging radar (Synthetic
Aperture Radar - SAR) data, the DNs represent the strength of a
radar pulse returned to the antenna. For digital terrain models
(DTMs), the DNs represent terrain elevation. No matter what the
source, all these types of data can be stored in a raster format.
By applying mathematical transformations to the digital numbers,
ER Mapper can enhance image data to highlight and extract very
subtle information that would be impossible using traditional manual
interpretation techniques. This is why image processing has become
such a powerful tool for all types of earth science applications. The
exercises in this manual provide many examples that illustrate how
image processing is typically used to enhance image data and
extract information.
Many image datasets have multiple bands (or layers) of data
covering the same geographic area, each containing a different type
of information. For example, a SPOT HRV-XS satellite image has
three bands of data, each recording reflectance from the earth’s
surface in a different wavelength of light. Since each band records
reflectance in a different part of the spectrum, this type of data is
often called multispectral data. Many powerful image processing
techniques have been developed to combine various bands from
multispectral images to highlight specific types of earth science
information such as vegetation abundance, water quality
parameters, or the types of minerals present at the earth’s surface.
Image processing
applications
10
Image processing has become an important tool for a wide range of
earth science mapping, analysis, and modeling applications.
Following are just a few of the many applications for which image
processing is commonly used:
•
land use/land cover mapping and change detection
•
agricultural assessment and monitoring
•
coastal and marine resource management
•
mineral exploration
•
oil & gas exploration
•
forest resource management
•
urban planning and change detection
•
telecommunications siting and planning
•
physical oceanography
•
geology and topographic mapping
Image processing with ER Mapper
•
Traditional image
processing
sea ice detection and mapping
Image processing was first developed on large mainframe computers
in the 1960s to process images from planetary satellites. To process
an image, you specified the name of the file to process, the type of
operation you wanted to perform, then waited for the system to
process the data and write the results to a new image file on disk
(shown in the diagram below). You then used a separate display
program to view the output file and evaluate your results.
Image processing
operation
RASTER
FILE1
RASTER
FILE2
With traditional systems, the changes resulting from the image
processing operation are saved in a separate output raster file.
With the introduction of powerful workstations in the 1980s,
processing of large images could now be performed on the desktop.
Surprisingly, nearly all image processing products on the market
today are still designed around this “disk-to-disk” approach from the
1960s. This means that to perform a processing operation that
requires several steps, you need to write an intermediate file to disk
for each step. Only when the final file is created can you view your
desired results. This approach can consume tremendous amounts of
time and disk space, and if the result is not what you intended, you
must often start all over again.
ER Mapper image
processing
Recognizing the restrictions inherent in traditional image processing
software, the creators of ER Mapper developed an entirely new
approach. Instead of writing a file to disk for each processing step,
ER Mapper lets you combine many processing operations into a
single step, and render the results directly to your screen display in
near real-time. (In most cases, no processed copies of your original
data are written to disk unless you request to do so.) The set of
processing steps you apply to your data is called an “algorithm” in
ER Mapper.
Image processing with ER Mapper
11
With ER Mapper, you can save only a description of the processing
steps you wish to apply to the data (the algorithm), not separate
processed copies of the original raster data file. By storing the
processing steps separately from the actual data, image processing
becomes faster, easier to learn, and more interactive. If required,
you can save the processed image in a number of formats including
ER Mapper Raster Dataset (.ers).
In ER Mapper, algorithms can be used for simple viewing of data, or
for very complex processing and modeling operations involving
many images, transformations of the data, and overlays of other
types of data. Examples of common image processing operations
that become much easier using algorithms include image merging
(data fusion), image mosaicing, and any type of mathematical
transformations such as band ratios, Principal Components, Tasseled
Cap transforms, and others.
The algorithms design also allows ER Mapper to handle the next
generation of very high resolution satellite imagery much more
efficiently than traditional systems. These one to three meter spatial
resolution datasets will have large file sizes for the area of coverage,
so reducing the need to write processed copies of the data to disk is
a very important consideration.
12
Image processing with ER Mapper
Image processing
tasks
A flowchart of typical image processing tasks is summarized in the
following diagram, from data import through processing to final
output:
Image processing with ER Mapper
13
Data read/import
The first step in image processing is reading the data you want to
use into ER Mapper. Typically the data might be stored on magnetic
tape, CD- or DVD-ROM, or other media. There are two primary types
of data you may want to read into ER Mapper: raster and vector.
Raster image data is the type used as input to image processing
operations. Typical sources include satellite images, digitized aerial
photographs, digital terrain models (DTMs), and geophysical and
seismic survey data. ER Mapper can directly read image data in the
following formats:
•
ER Mapper Raster Dataset (.ers)
•
ER Mapper compressed image (.ecw)
•
ESRI BIL and GeoSPOT (.hdr)
•
Windows BMP (.bmp)
•
GeoTIFF/TIFF (.tif, .tiff) - with read support for TIFF world files
(e.g., .tfw)
•
JPEG (.jpg) - with read support for JPEG world files (e.g., .jgw)
•
JPEG 2000 compressed image (e.g .jp2)
•
USGS Digital Ortho Quad (.doq)
•
RESTEC/NASDA CEOS (.dat)
•
DOQQ version 1 support (.doq)
•
Landsat 7 FastL7A (.fst)
•
Aster/MODIS/Landsat7/EODIS/SPOT Vegetation (.l1g, .l1r,
.met, .hdf)
•
National Imagery Transmission Format (.ntf)
You have to import image data that is not in one of the formats listed
above. When you import a raster image file (using ER Mapper’s
import utility programs), ER Mapper converts the data into
ER Mapper Raster Dataset format by creating two files:
14
•
a binary data file containing the raster data, in band interleaved
by line (BIL) format
•
a corresponding ASCII header file with an .ers file extension
Image processing with ER Mapper
Vector data is stored as lines, points, and polygons. Many geographic
information system (GIS) products use vector data structures
because it is more efficient for representing discrete spatial objects
like roads (lines), sample locations (points), or political boundaries
(polygons). In an image processing product, it is often helpful to
overlay vector data on top of a raster image backdrop, for example
overlay a network of known roads on a satellite image. When you
import a vector file (using ER Mapper’s import utility programs),
ER Mapper converts the data and creates two files:
Image display
•
an ASCII data file containing the vector data
•
a corresponding ASCII header file with an .erv file extension
After importing the data, the next step is usually to display the image
on your monitor to evaluate the data quality and geographic area of
coverage. If the data is of poor quality or does not cover your area
of interest, you might decide not to proceed any further and try to
obtain better data.
There are several ways in which data can be viewed, including simple
black and white or pseudocolor displays, and red-green-blue (RGB)
or hue-saturation-intensity (HSI) color composite displays. The way
in which you choose to display your raster data is called the “Color
Mode” in ER Mapper.
In addition to displaying the data, you may want to view statistical
information about it. Statistics are often good indicators of image
quality. You may want to calculate statistics for the image, such as
the mean value in each band, and view them in a tabular format. Or
you may want to view statistical information in a graphical format
using tools like histograms, scattergrams and traverse profiles.
Image geocoding
Many times, raster image data is supplied in a “raw” state and
contains geometric errors. Whenever accurate area, direction, and
distance measurements are required, raw image data must usually
be processed to remove geometric errors and/or rectify the image to
a real world coordinate system.
•
Registration is the process of geometrically aligning images to
allow them to be superimposed or overlaid.
•
Rectification is the process of geometrically correcting raster
images so they correspond to real world map projections and
coordinate systems (such as Latitude/Longitude or
Eastings/Northings).
•
Orthorectification is a more accurate method of rectification
because it takes into account terrain and sensor (camera)
calibration details. Advanced orthorectification also uses platform
position information.
If your application requires that your images be registered to one
another or rectified to a map projection, you will use ER Mapper’s
Ortho and Geocoding Wizard to do this.
Image processing with ER Mapper
15
Image mosaicing
A mosaic is an assemblage of two or more overlapping images used
to create a continuous representation of the area covered by the
images. ER Mapper automates the building of image mosaics
because co-registered images referenced in the same processing
algorithm are automatically displayed in their correct geographic
positions relative to each other. This means that you can work with
each image file in the mosaic as a separate entity, and you are not
required to write all images to one large file on disk in order to
process and enhance them.
Image enhancement
Image enhancement refers to any one of many types of image
processing operations used to digitally process image data to aid
visual interpretation or extract quantitative information meaningful
to the user. Image enhancement is what many people commonly
think of as “image processing.”
In ER Mapper, image enhancement operations are greatly simplified
by the “algorithms” processing concept. Nearly all types of image
enhancement operations can be applied and displayed in real time to
provide truly interactive control without writing temporary files to
disk.
Typical image enhancement operations include:
16
•
Image merging (data fusion) – Combine images with different
qualities to aid interpretation. For example, merge Landsat TM
and SPOT Pan to combine TM spectral information with SPOT Pan
spatial detail.
•
Colordraping – Drape one type of data over another to create a
combined display allowing analysis of two or three variables. For
example, drape a satellite-derived vegetation map over an
airborne magnetics image of the same area, or overlap
magnetics and radiometrics images to check for correlations.
•
Contrast enhancements – Improve image presentation by
maximizing the contrast between light and dark portions (or high
and low data values) in an image. Or, highlight a specific data
range or spatial area in an image.
•
Filtering – Enhance edges, smooth noise, or highlight or suppress
specific linear or spatial features in images. For example, apply a
gradient directional filter to highlight linear features tending
north-south in an image. ER Mapper also includes Fast Fourier
Transformations for filtering in frequency domain space.
•
Formula processing – Apply mathematical operations to combine
multiple bands of image data or derive specific thematic
information. Examples include thresholding, differencing, ratios,
Principal Components Analysis, and spatial modeling.
Image processing with ER Mapper
Dynamic Link layers
•
Classification – Statistically group or cluster image data values
into thematic categories or feature classes. For example, classify
a Landsat satellite image to yield a thematic map of land cover
types. (Raster representations of the spatial cover types can also
be converted to vector polygons for export to GIS systems.)
•
Color balancing – Balance the colors of mosaiced airphoto images
to create seamless joins between them.
Dynamic Links are a special ER Mapper feature that let you link to
data in external products or file formats, and display the data on top
of raster images without the need for importing the files. Dynamic
Links can link to raster, vector, or tabular (point) datasets, so you
can access and integrate all your geographic information. ER Mapper
provides Dynamic Links to several popular products and file formats.
The procedure is fully documented so you can also create your own
links to any other product or format you desire.
Types of Dynamic Links include:
•
Links to GIS products – Extract and display vector data from GIS
products such as ARC/INFO. GIS links are often used to overlay
vector data such as road networks, political boundaries, or land
use categories.
You can display, edit, and save ARC/INFO coverage files directly
in ER Mapper. See the ER Mapper User Guide for details.
Map composition
•
Links to database products – Extract and display tabular (point
location) data from database products such Oracle. Tabular links
are often used to overlay georeferenced point location symbols
such as cities, well locations, or ground truth sample sites.
•
Links to external file formats – Display specialized annotation,
vector data, or other data stored in PostScript, DXF, DGN, or
other standard file formats.
You can use ER Mapper’s built-in Annotation and Map Composition
tools to create top quality maps combining raster, vector, and
tabular data. Annotation lets you draw directly on-screen using text,
line, polygon, and other annotation tools, and specify fill color,
shading, line styles, user-defined symbols, and group and move
objects. Vector annotation files created in ER Mapper can also be
exported to external file formats for use in other products.
You can layout and compose maps comprising multiple processed
images and size and scale map output as desired. All map objects
are defined as full color PostScript and you can easily add custom
map objects such as company logos or special north arrows.
Image processing with ER Mapper
17
Data save/export and
hardcopy
Once you have completed processing your data, ER Mapper lets you
translate raster and vector image data to external standard file
formats or print to over 200 different hardcopy devices and any
Windows printer.
You can save raster images directly to the following formats:
•
ER Mapper Raster Dataset (.ers)
•
ER Mapper compressed format (.ecw)
•
ER Mapper Virtual dataset (.ers)
•
ESRI BIL and GeoSPOT (.hdr)
•
Windows BMP (.bmp)
•
GeoTIFF/TIFF (.tif, .tiff)
•
JPEG (.jpg)
•
JPEG 2000 compressed format (.jp2)
•
UDF (.ers and .hdr)
•
National Imagery Transmission Format (.ntf)
UDF (Universal Data Format) saves the image with an ER Mapper
(.ers) and ESRI BIL GeoSPOT (.hdr) file. This allows it to be directly
read by a number of image processing applications.
You may also want to export vector annotation or vectorized
thematic data to a GIS product.
The compressed formats use ECW (Enhanced Compressed Wavelet)
and JPEG 2000 compression to make the output image file size
considerably smaller than the original with minimal loss in quality.
The single .ecw or .jp2 file contains embedded georeferencing
information that can be used by ER Mapper and external GIS
applications.
The ECW JPEG 2000 SDK caters for military-grade applications by
complying with NITF JPEG 2000 standards. With the ECW JPEG 2000
you can compress to NITF/NSIF BIIF NPJE, EPJE compliant
codestreams. Use ER Mapper to compress to NITF 2.1 files with
embedded JPEG 2000 codestreams.
Hardcopy printing is often the final goal of processing and annotating
images, and ER Mapper provides unsurpassed hardcopy support and
output to standard graphics file formats. ER Mapper also includes a
built-in PostScript-compatible rendering engine, so you get
PostScript-quality output (such as beautiful, smooth text) on any
supported device, whether the device supports PostScript or not.
18
Image processing with ER Mapper
You can also easily print at exact sizes and map scales, and
automatically print large images in strips for mosaicing large image
displays. Supported hardcopy devices include any Windows printer,
film recorders, dye sublimation printers, inkjet printers, and
electrostatic plotters. Graphics file formats include PostScript, TIFF,
Targa, CGM, and CMYK and RGB color separations.
ER Mapper
algorithms
ER Mapper is supplied with many ready-made algorithms to make
your image processing tasks fast and efficient.
See the “ER Mapper algorithms, filters and formulae”
chapter for details.
ER Mapper
wizards
ER Mapper has a number of useful wizards which simplify and
automate much of the image processing.
These are described in the ER Mapper User Guide and
summarized in the “ER Mapper Wizards” chapter of this
manual.
Image processing with ER Mapper
19
20
Image processing with ER Mapper
ER Mapper user interface
This chapter introduces the basic use of the ER Mapper graphical
user interface. It gives you practice using menus, toolbars, dialog
boxes, and image windows, and loading and displaying image
processing algorithms.
In order to complete the exercises in this manual, you will need
to access the sample images and algorithms supplied with
ER Mapper. If needed, ask your system manager for the location
of the ER Mapper software directory at your site.
User interface
components
This section provides a brief introduction to the main components of
ER Mapper’s graphical user interface (GUI). You can perform nearly
all operations by pointing and clicking with the mouse, and very little
typing on the keyboard is required. The GUI is part of ER Mapper’s
original design, so it is well integrated and easy to learn and use.
Using mouse buttons
When using ER Mapper, use the left button on your mouse to
perform operations like selecting items from menus, manipulating
image windows, and drawing annotation. In this manual, all actions
are performed with the left mouse button unless otherwise indicated.
The following table explains terms used in this manual to describe
actions you perform with the mouse.
Term
Meaning
Point
Position the mouse pointer on an item.
Click
Point to an item, then quickly push and release the left mouse button.
Right-click
Point to an item, then quickly push and release the right mouse button.
Double-click
Point to an item, then quickly click the left mouse button twice.
Drag
Point to an item. Then press and hold down the left mouse button as you move
the pointer to a new location, then release the button.
Shift-click or
Hold down the Shift key or Ctrl key on your keyboard, then click.
Ctrl-click
Shift-drag or Ctrl- Hold down the Shift key or Ctrl key on your keyboard, then drag the mouse.
drag
ER Mapper user interface
21
The symbol representing the mouse pointer on the screen changes
shape depending on what you are pointing to and the task you are
performing.
Pointer
Location on the screen
Function
Menu bars and buttons; or inside
image window
Choose menu commands and click buttons; point
to the image to see data values or coordinates.
Text fields
Type or select text, or reposition the insertion
point.
Inside the current image window
Zoom the image within the image window.
Inside the current image window
Drag a box over an area to fill image window.
Inside the current image window
Pan the image within the image window.
Inside inactive image windows
Select an inactive window to become the current
window.
In image windows when annotation
tools are selected
Draw annotation and map composition objects.
The ER Mapper main
menu
When you start ER Mapper, the main menu appears. The main menu
has two primary components–the menu bar and rows of toolbar
buttons.
Title bar
Menu bar
Buttons
Toolbars
22
ER Mapper user interface
Menu bar
Lets you select commands used to carry out actions in ER Mapper. To select a
command from the menu bar, click on the name of the menu to open it, then
click the desired command name.
Toolbar buttons
Shows groups of buttons to let you carry out common tasks quickly. To choose
a function from a toolbar, click on the desired button.
Tool tips
Place the cursor on any toolbar button and within a couple of seconds the
function of that toolbar button is displayed in a small text window just below
the cursor
ESG Color Enhance
The ESG ColorEnhance wizards provide a set of tools for enhancing the color
of your images.
ESG Quickstretch
The ESG Quickstretch wizards let you “one click” to apply a variety of contrast
enhancements to an image or mosaic of images.
ESG Utilities
The ESG Utilities wizards provide a set of “power tools” aimed at increasing
productivity with an emphasis on automating common tasks.
Using ER Mapper toolbars
Toolbars give you quick access to many common functions, such as
saving an image processing algorithm or printing a hardcopy.
ER Mapper also provides optional toolbars for specific tasks and
image processing applications. To hide or display various toolbars,
use the Toolbars menu. To get short help for any toolbar function,
point to the button and read the tool tips.
ER Mapper provides toolbars for many common tasks, and also
toolbars for building processing algorithms commonly used in
remote sensing applications such as forestry, geophysics, and map
generation. The functions of the Standard, and Common Functions
toolbars are summarized below.
Standard
Provides quick access to standard commands for opening and saving
algorithms, printing, starting and stopping algorithm processing, and
changing the mouse pointer. Most functions are also available from the
menu bar.
Common Functions
Provides quick access to commonly used functions, such as creating general
types of algorithms, viewing and editing components of an algorithm.
For a description of the other toolbars, see the “ER Mapper
menus and toolbars” chapter.
Using ER Mapper’s scripting language, you can also create your own
customized toolbars for specific tasks and functions.
For more information on creating custom toolbars, see the
online ER Mapper User Guide.
ER Mapper user interface
23
Using dialog boxes
When you select menu commands or click toolbar buttons, dialog
boxes often appear for you to choose options to control your image
processing tasks. Some dialog boxes, such as the File Chooser, can
disappear when you make your selection. Other dialogs can remain
open for setting options for as long as you want to use them.
click to load
file
close dialog
without action
text fields
(click to
place cursor)
drop-down
list (click to
open)
displaysetup
options
access online
help for this
function
To resize a dialog box, drag one of its corners or edges to the desired
size. ER Mapper automatically resizes the dialog box intelligently, so
that any central display areas are enlarged, and the layout of buttons
remains the same. After resizing, the dialog retains your new size for
the current ER Mapper session.
Using the File Chooser
dialog boxes
24
When you choose to open or save a dataset, algorithm, or other file,
ER Mapper displays a File Chooser dialog box. The central window
contains a list of directories, or files in the current directory.
ER Mapper user interface
menu bar to
navigate and
mark directories
current directory
scroll to view
other items
in directory
click to move up
and down one
directory level
file types
click to view
comments
click to load and
close dialog box
click to load and leave dialog open
To open a file or directory displayed in the scroll list window, either
double-click on it, or click once to select it and click the OK or Apply
button to open it.
You can see two levels of directories and/or files by widening the
file chooser dialog box (drag one of the sides).
The File Chooser menus at the top have the following functions:
History menu
Use to change the File Chooser’s current directory. The menu has two parts:
the upper portion lists most recently visited directories and the lower
portion lists marked directories.
Special menu
Use to change to your home directory or to mark or unmark a directory (any
directory may be marked for fast access using the History menu).
View menu
Use to sort the contents of the current directory by name, date modified or
date created.
Volumes menu
Use to access volumes or disk drives on your network.
ER Mapper user interface
25
Directories menu
Use to change to any directory defined by your preferences settings.
ECW URL History
List of the URLs of the most recently accessed image files from an Image
Web Server.
Using the online help
system
ER Mapper provides an extensive online help system with both
simple overviews and detailed descriptions of all features and
functions. There are two ways to access help:
Help menu
Lets you browse all the standard ER Mapper manuals online, and go
between manuals and topics using hypertext links.
Help buttons
The Help button inside dialog boxes gives you context-sensitive help. If
needed, you can navigate to view more detailed information using the
hypertext links.
Typing text in text fields
To enter text for naming files or changing values in dialog boxes,
ER Mapper provides text fields. When you point to a text field, the
pointer shape changes to an I-beam. To enter text, click anywhere
inside the text field to place the text cursor.
To select existing text, you can drag through the desired portion or
double-click on a word or numeric value to select it. Text that is
selected become reverse highlighted and any subsequent typing
replaces it.
Hands-on
exercises
What you will
learn...
26
The following hands-on exercises introduce you to the basic concepts
of using menus and dialog boxes and managing image windows.
After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
•
Choose options from menus and toolbar buttons.
•
Display and hide toolbars.
•
Open an empty image window.
•
Open an image processing algorithm into a window.
•
Move and resize an image window.
•
Zoom and pan the image within the window.
•
Manipulate multiple image windows on the screen.
•
Close image windows.
ER Mapper user interface
1: Using menus
and toolbars
Objectives
Learn to open and make selections from menus, use toolbars, and access online help.
Move the ER Mapper main
menu around the screen
1. Position the mouse pointer on the ER Mapper main menu title bar,
then drag it to the lower-left part of the screen.
Pointing to the title bar and dragging is how you move dialog boxes
and image windows around the screen.
2. Drag the main menu to the upper-right corner of the screen.
This is the recommended position for the main menu for the
exercises in this tutorial.
Open a menu to display
its commands, then close
the menu
1. Click on the View menu button; a list of commands under the menu
displays.
The small arrows next to Quick Zoom and Statistics indicate that
they have additional commands under them.
2. Click on the Statistics command to display its submenu.
3. Click anywhere outside the main menu to close the open menus
without making a selection.
In the rest of this manual, selecting commands from menus is
indicated as follows: “From the Edit menu, select
Preferences...” (which means click on Edit in the menu bar,
then click on the Preferences command).
Select the Print command
from the menu bar
1. From the File menu, select Print.
The Print dialog box appears with options for printing hardcopy.
2. Click the Cancel button to close the dialog box.
ER Mapper user interface
27
Select the Print command
from the Standard
toolbar
1. On the Standard toolbar, click the Print
button.
The same Print dialog box appears again. Using toolbar buttons is
often a faster way to access many commands in ER Mapper.
2. Click the Cancel button to close the dialog box.
Many common commands on the menu bar, such as Print, are
also available on the Standard toolbar. Use whichever is fastest
or most comfortable.
Display and hide a toolbar
1. From the Toolbar menu, select Forestry.
A third row of toolbar buttons appears on the main menu below the
Standard and Common Functions toolbars. This toolbar has
buttons for common image processing techniques used in forestry
applications.
2. Point the cursor to any button on the toolbar.
A description of the button function displays in the small text field
just below the cursor.
3. From the Toolbar menu, select Forestry again.
The Forestry toolbar buttons disappear from the main menu. Use
the Toolbar menu to display or hide any toolbar. (It is
recommended that you always display the Standard and Common
Functions toolbars.)
2: Opening
windows and
algorithms
Objectives
To display an image in ER Mapper, you first open an empty image
window, then load and display an image processing algorithm. The
algorithm references a raster data file on disk and the processing
steps ER Mapper uses to enhance and render the data on the screen
display (You will learn more about algorithms later). You can have as
many different image windows open on the screen as you need.
Learn to open image windows on your computer display and open and run an image
processing algorithm stored on disk.
Open a new empty image
window
1. From the File menu, select New.
28
ER Mapper user interface
An empty image window opens in the upper left corner of the screen.
The window title bar reads “Algorithm Not Yet Saved” because no
processing algorithm is associated with this image window yet.
Open and display an
image processing
algorithm
1. From the File menu, select Open....
The Open file chooser dialog box opens.
2. From the Directories menu, select the path ending with the text
\examples (The portion of the path name preceding it is specific to
your site).
3. Double-click on the directory named ‘Data_Types’ to open it.
4. Double-click on the directory named ‘Landsat_TM’ to open it (Scroll
if needed to view it first).
The list of example algorithms for processing Landsat Thematic
Mapper (TM) satellite imagery displays.
5. Double-click on the algorithm named RGB_321.alg. (Scroll down if
needed to view it first).
ER Mapper runs the algorithm and displays an enhanced Landsat TM
image of San Diego, California in the image window. This algorithm
displays bands 3, 2, and 1 of the Landsat image as an RGB color
composite image, with band 3 in the red display channel, band 2 in
the green, and band 1 in the blue. Notice also that the algorithm
filename RGB_321 now appears in the title bar of the image
window.
Use the toolbar to open a
different processing
algorithm
1. Click the Open
button on the Standard toolbar.
The Open file chooser dialog box appears (This toolbar button has
the same function as selecting Open... from the File menu).
The algorithm named RGB_321 in the Data_Types\Landsat_TM
directory is already highlighted since it is currently loaded into the
image window.
2. Double-click on the algorithm named RGB_541.alg.
ER Mapper runs the algorithm and displays a color composite of the
same Landsat image, this time using bands 5, 4, and 1. Notice that
the title bar also changes to show the filename of the new algorithm.
ER Mapper user interface
29
By default, ER Mapper runs the algorithm automatically for you
when you open it from disk. You can also reprocess the data at
any time by clicking the Refresh
button.
3: Resizing
windows and
zooming/panning
Objectives
Learn to move and resize image windows, zoom (magnify) part of an image and pan
(scroll) to other parts of an image.
Move the image window
on the screen
1. Point the mouse at the image window title bar, then drag it to
another part of the screen.
2. Drag the image back to the upper-left part of the screen.
Like dialog boxes, dragging images by the title bar is how you move
them around the screen.
Resize the image window
1. Move the mouse pointer directly over the lower-right corner of the
image window–the pointer shape changes to a double ended arrow.
2. Drag the lower-right corner to make the window about twice its
original size, then release.
Dragging any side or corner of an image window lets you change the
default window size as you desire.
When you resize a window, ER Mapper maintains the size of the
image inside the window. Empty areas on the sides are filled
with a cross-hatch pattern to indicate that no data is displayed
there.
Set the mouse pointer to
Zoom mode
1. On the Common Functions toolbar, click the Zoom Tool
button.
This tells ER Mapper to use the mouse pointer for zooming when it is
positioned inside an image window. Also notice that the Zoom Tool
button becomes depressed to indicate that it is the active pointer
mode.
30
ER Mapper user interface
2. Move the pointer inside the image window.
The mouse pointer displays as a magnifying glass icon.
Zoom in and out of the
image with the mouse
1. Position the pointer in the center of the image, and click the left
mouse button.
The image zooms in by 50%.
2. Position the pointer in the center of the image, hold down the Ctrl.
key while clicking the left mouse button.
The image zooms out by 50%.
3. Position the pointer in the image, and then drag it up and down.
As you drag the pointer down the image is magnified, i.e., you zoom
into it. When you drag the pointer upwards, the image gets smaller,
i.e., you zoom out.
Set the mouse pointer to
ZoomBox mode
1. On the Common Functions toolbar, click the ZoomBox Tool
button.
This tells ER Mapper to use the mouse pointer for creating a zoom
box when it is positioned inside an image window. Also notice that
the ZoomBox Tool button becomes depressed to indicate that it is
the active pointer mode.
2. Move the pointer inside the image window.
The mouse pointer displays as a magnifying glass and box icon.
Zoom in (magnify) an
area of the image with
the mouse
1. Position the pointer near the upper-left center of the image, then
drag to the lower-right to define a box.
When you release the mouse, ER Mapper runs the algorithm again
and magnifies (or “zooms in”) on the area of the image you defined
with the box. Dragging a zoom box is a fast way to magnify an area
of interest. (There are other zooming functions you will learn about
later.
Set the mouse pointer to
Hand mode
1. On the Common Functions toolbar, click the Hand Tool
ER Mapper user interface
button.
31
This tells ER Mapper to use the mouse pointer for panning when it is
positioned inside an image window. Also notice that the Hand Tool
button becomes depressed to indicate that it is the active pointer
mode.
2. Move the pointer inside the image window.
The mouse pointer displays as a hand icon.
Pan (scroll) the image
within the window with
the mouse
1. Click on the image. and drag it to a new position in the image
window.
The hand pointer will grab the image and move it (pan) to the new
location.
Zoom back out to view
the full image extents
1. From the View menu, select Quick Zoom and then select Zoom to
All Datasets.
ER Mapper runs the algorithm again and zooms back out to display
the full extents of the Landsat image data. The Quick Zoom
submenu provides many options for zooming in or out to specific
datasets, setting window geolinking, and other options you will learn
more about later.
Right-clicking in the image window will also bring up a quickoptions pop-up menu with Quick Zoom. This menu also has
other options such as Stop Processing (ESC), Refresh Image
(F5), Clip, changing the mouse pointer to Hand, Zoom, Zoom
Box or Pointer tools, common File operations and bringing up
the Algorithm, Cell Values Profile and Cell Coordinate
dialog boxes.
Zoom and pan using
buttons for predefined
options
In addition to using the mouse, ER Mapper also lets you zoom and
pan using buttons to invoke predefined zoom and pan functions.
1. From the View menu, select Geoposition....
The Algorithm Geoposition Extents dialog box appears.
You can also click on the Geoposition Window button
on
the Algorithm window to open the Algorithm Geoposition
Extents dialog box
2. In the row of tabs at the top, click on the Zoom tab to turn it on.
32
ER Mapper user interface
The contents of the Algorithm Geoposition Extents dialog change
to show sets of buttons for zooming and panning the image within
the window.
3. In the buttons labeled ‘Zoom,’ click the Zoom out 50%
button.
ER Mapper runs the algorithm and zooms out to 50% of the previous
display resolution.
For all icons on buttons under ‘Zoom’ and ‘Pan,’ the black square
represents the current image, and the white box represents how
the size or position of the image will change after the button is
clicked.
4. In the buttons labeled ‘Set Extents To,’ click Previous.
ER Mapper zooms out to the previous image display extents.
5. Under ‘Zoom,’ click on the Zoom in 100%
button.
ER Mapper magnifies the images to two times (100%) of the
previous display resolution (and keeps the image center point
constant).
6. Under ‘Pan,’ click on the Pan left
button.
ER Mapper pans or scrolls the image 50% to the left (the previous
center point is now on the far right side of the image).
7. Under ‘Pan,’ click on the Pan upper-right
button.
ER Mapper pans the image 50% to the upper-right (the previous
center point is now on the lower-left corner of the image).
8. Experiment with other buttons under Zoom and Pan to see their
effect.
9. Under ‘Set Extents To,’ click the All Datasets button.
ER Mapper resets the image extents to fit the entire dataset in the
image window.
10. Click Close on the Algorithm Geoposition Extents dialog to close
it.
ER Mapper user interface
33
4: Managing
multiple image
windows
Objectives
Learn to open a second image window, specify overlap priority between windows,
activate an image window, and close image windows.
Open a second image
window
1. From the File menu, select New.
ER Mapper opens a new image window. As with all new image
windows, it has no algorithm associated with it yet.
Open and display a
processing algorithm in
the new window
1. From the File menu, select Open....
The Open file chooser dialog box appears.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the directory named ‘Data_Types’ to open it.
4. Double-click on the directory named ‘SPOT_Panchromatic’ to open it.
The list of example algorithms for processing SPOT Panchromatic
satellite imagery displays.
5. Double-click on the algorithm named grayscale.alg.
ER Mapper runs the algorithm and displays a SPOT Panchromatic
satellite image the San Diego (the same geographic area covered by
the Landsat image in the other window). The SPOT Pan data provides
greater spatial detail than the Landsat data, but has only one
spectral band which is displayed in grayscale.
Move the SPOT window to
overlap with the Landsat
window
1. Drag the image window titled Grayscale to the center of the screen
until it partially overlaps with the Landsat ‘RGB_541’ image window.
34
ER Mapper user interface
Your windows should be similar to the following diagram:
Move one window in front
of the other
1. Click on the title bar of the window with the algorithm description
titled RGB_541.
The Landsat window moves in front of the SPOT window where there
is overlap.
2. Click on the title bar of the window with the algorithm description
Grayscale.
The SPOT window now moves in front of the Landsat window where
there is overlap. Clicking on the title bar of a window or dialog box
bar lets you choose which window or dialog box to display on top of
others.
Select a window to be the
active window
The “active” image window is the one you want to currently work
with, such as zooming, loading a new processing algorithm, or
editing the current algorithm.
1. Look at the title bar of the SPOT Panchromatic window and notice the
three asterisks (***) on either side of the window title.
The three asterisks indicate that this is the active (or current)
window of the two.
2. Move the pointer inside the image area of the window with the
algorithm description titled “RGB_541.”
The pointer shape changes to a pointing hand. (This happens
whenever you move from the active window to any inactive image
window.)
3. Click anywhere inside the Landsat image window or on the Title Bar.
It now becomes the active window and three asterisks appear next
to the title.
4. Click inside the SPOT window or on the Title Bar again to make it
active.
ER Mapper user interface
35
A window can be active and still be covered by another “inactive”
window. To move the active window to the front, click on its title
bar.
Close both image
windows
1. Close one image window using the window system controls:
•
Select Close from the window control-menu.
The window closes and disappears from the screen.
2. Close the other image window by repeating Step 1.
The window closes and disappears from the screen. Only the
ER Mapper main menu is now open.
What you learned
36
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Choose options from menus and toolbar buttons.
•
Display and hide toolbars.
•
Open an empty image window.
•
Open an image processing algorithm into a window.
•
Move and resize an image window.
•
Zoom and pan the image within the window.
•
Manipulate multiple image windows on the screen.
ER Mapper user interface
Handling images
This chapter introduces the basic concepts involved in creating a
simple image processing algorithm. You learn about the interface
ER Mapper provides for creating and editing algorithms (the
Algorithm window). As an application example, you learn how to
create an algorithm that processes a Landsat TM satellite scene to
render an image showing patterns of vegetation in the area (a
“vegetation index” image).
This lesson is a “quick start” for creating a simple algorithm. You
learn more about the concepts and procedures covered here in
later chapters.
About the
algorithms
concept
The goal of all image processing is to enhance your data to make it
more meaningful and help you extract the type of information that
interests you. To make this procedure faster and easier, Earth
Resource Mapping developed a new image processing technique
called “algorithms.” Understanding how to use algorithms is the key
to understanding how to use ER Mapper effectively.
What is an algorithm?
An algorithm is a list of processing steps or instructions ER Mapper
uses to transform raw data on disk into a final, enhanced image. In
this sense, algorithms let you define a “view” into your data that you
can save, reload, and modify at any time.
To read more about algorithms, see the “ER Mapper
algorithms, filters and formulae” chapter.
The majority of exercises in this tutorial ask you to build algorithms
from scratch so you become familiar with and thoroughly understand
the basic concepts. However, you will also use the automatic
algorithm creation toolbar buttons from time to time to understand
how they work.
The Algorithm
window
The Algorithm dialog is a special dialog box that serves as your
“command center” for creating and editing algorithms in ER Mapper.
To open the Algorithm dialog, you can select Algorithm... from the
View menu or click the Edit Algorithm
toolbar button. The key
components of the Algorithm dialog are labeled below and
described in the table that follows.
Handling images
37
38
•
Data structure diagram: Shows a list of surfaces and layers
•
Surface: A group of raster and/or vector data layers that combine
to create a view or image. A single algorithm can have multiple
surfaces that become independent entities when viewed in 3D
mode.
•
Layers: Components of a surface that contain data used to
construct an image. Different layer types can contain raster or
vector data, and processing for each layer is controlled
independently from the others.
•
View Mode: Sets the manner in which data is displayed as two
dimensions (2D) normal or page layout, or three dimensions
(3D).
•
Tab pages: Display categories of options for controlling the image
•
Process diagram: Used to control the processing operations
applied to images in the currently selected layer (displayed when
Layer tab is selected).
contained in the current algorithm using a hierarchy or “tree”
structure. Select (click on) a surface or layer to change its
options using the Tab pages.
display and processing techniques, such as Layer for options for
the current layer or Surface for options that apply to an entire
surface.
Handling images
The Process Diagram
When the Layer tab is selected, the horizontal row of buttons in the
right-hand panel of the Algorithm dialog are called the process
diagram. They are used to define your image processing operations
for the currently selected data layer. Each button in the diagram
controls a specific image processing function.
As the arrows indicate, the processing stream flows from left to right.
Typically, you may specify an image to be used, the bands within the
image to be processed, then apply processing using formulae, filters,
transforms or other options to create your desired image. ER Mapper
compiles all the processing steps you specified and renders the
resulting image to the screen display. The name and function of the
main processing stream buttons are as follows.
Button
Function
Dataset
Use to load an image from disk, or edit or view information or comments about
an image.
Band Selection
Use to select one or more bands in the image for use in generating an image (a
drop-down list).
Formula
Use to enter, load, or save a formula to perform image algebra and other
arithmetic operations.
Filter
Use to add or delete one or more spatial filters. (There are both pre- and postformula Filter buttons.)
Transform
Use to adjust image contrast and brightness. (There are both pre- and postformula Transform buttons.)
Sunshade
Use to specify artificial illumination of the image to create shaded relief effects.
A cross or “X” through the button indicates that the function is
not active in the current data layer. In addition, there are other
buttons for some layer types that you will learn about later as
you go through more advanced exercises from the online
ER Mapper Tutorial manual.
Hands-on
exercises
Handling images
These exercises show you how to initially display an image, and how
to build, save, and reload a simple image processing algorithm. It
also shows how you can easily change the image to view it in 3D
perspective.
39
These exercises briefly introduce concepts and procedures that
are explained in more detail later in this workbook and in the
online manuals.
What you will
learn...
Before you
begin...
After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
•
Load a new image and choose which bands to display
•
Use the Algorithm dialog to define a processing algorithm
•
Change the color lookup table for an image
•
Add a formula to an algorithm
•
Add text labels and comments to an algorithm
•
Save the processing algorithm to disk
•
Reload and view the saved algorithm
•
Add a Height layer to view the image in 3D perspective
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Loading and
displaying images
Objectives
Learn to open an image window and the Algorithm window, load an image dataset,
and display the image on-screen. You will also learn to display different bands in the
image, and change the lookup table ER Mapper uses to assign colors to the image.
Open an image window
and the Algorithm
window
1. From the View menu, select Algorithm....
A new empty image window opens in the upper-left corner of the
screen, and the Algorithm window opens in the lower-right.
ER Mapper remembers where you last positioned dialog boxes
on your screen. Therefore the Algorithm window could be
positioned differently to what is described above.
40
Handling images
The Layer tab is usually already selected when you first open the
Algorithm dialog box. Note that the Algorithm window shows one
Pseudocolor layer (labeled “Pseudo Layer”) in the left of the dialog,
with the red arrow pointing to it meaning that is the active layer.
If you open the Algorithm window when no image windows are
currently open (as in this case), ER Mapper opens an empty image
window for you automatically. This shortcut saves you the step of
opening a window.
Load a raster image into
the Pseudocolor layer
1. In the Algorithm window, click the Load Dataset
button on
the left side of the process stream diagram.
The Raster Dataset file chooser dialog box appears.
2. From the Directories menu, select the path ending with
\examples.
The scrolling list in the center now shows a list of directories
containing example images supplied with ER Mapper (such as
‘application...’ and others).
3. Double-click on the directory named ‘Shared_Data.’
A list of raster images is displayed. Note that each has an .ers file
extension. This is the file extension associated with raster files in
ER Mapper format.
4. Scroll down to view the image named
Landsat_TM_year_1985.ers, then double-click on it to load it.
The file chooser dialog box closes, and the image is loaded into the
Pseudocolor layer. Note that the layer now shows the name of the
image loaded (‘Landsat_TM_year_1985’), and the button left of the
name is now selected (indicating that the layer is turned on).
ER Mapper renders the image in the image window. The image is
displayed in a range of colors because the color table named
Pseudocolor is chosen.
ER Mapper remembers the last color table selected. Therefore,
it might not be Pseudocolor as described above.
Also note that Band Selection drop-down shows the label
‘B1:0.485_um.’ This indicates that band 1 of the Landsat image is
currently selected for the layer.
Select and display
different bands in the
Landsat image
Handling images
Landsat Thematic Mapper (TM) satellite images usually contain
seven spectral bands. You can choose to display any band (or a
combination of bands) in a raster data layer.
41
1. In the Algorithm window, click on the Band Selection
drop-down list in the process stream diagram.
A menu listing the seven different bands in the Landsat image
displays.
2. Click on the band labeled B2:0.56_um.
The menu closes and the new band appears in the Band Selection
field.
ER Mapper renders band 2 of the Landsat image in the image
window. (The colors look different to those for band 1 because the
range of data for band 2 is different than band 1. (You will learn
about data ranges and how to adjust image brightness and contrast
later.)
3. From the Band Selection drop-down list, select the band labeled
B7:2.215_um.
ER Mapper renders band 7 of the Landsat image in the image
window.
4. From the Band Selection drop-down list, again select the band
labeled B1:0.485_um.
ER Mapper renders band 1 of the Landsat image again.
The Stop Processing
button or Esc key can be useful when
you make a mistake, or when you want to take a quick look at
the results without waiting for processing of the entire image to
finish.
Press the Refresh Image
continue.
button for the processing to
When you are using the Color Mode named Pseudocolor (as you are
in this example), the Color Table controls the set of colors
ER Mapper uses to display the image.
5. In the Algorithm window, click on the Surface tab and then click on the Color
Table drop-down list button.
A menu listing available color lookup tables appears.
6. Click on the lookup table named green.
ER Mapper renders the image using shades of green. Lower data
values display as darker shades of green, and higher data values as
lighter shades.
When you change the color table, ER Mapper updates the image
display automatically to apply the new set of colors.
42
Handling images
7. From the ColorTable drop-down list, select brown_green.
ER Mapper renders the image using shades of brown for low data
values transitioning into shades of green for higher data values.
8. From the Color Table list, select grayscale.
ER Mapper renders the image using shades of gray. Lower data
values display as darker gray shades, and high data values as lighter
grays.
In Exercise 1, you have created the simplest type of algorithm: a
Pseudocolor algorithm that displays a single band of data using a
color lookup table to control the image coloring. You have not saved
the algorithm yet because you will modify it later.
2: Processing the
image
Objectives
Learn to develop a simple processing algorithm using a formula to highlight vegetation
in the image and to modify the image contrast and brightness on the screen display.
Load a vegetation index
formula into the layer
1. In the Algorithm window, click on the Layer tab and then click on
Edit Formula
in the process stream diagram.
The Formula Editor dialog box appears to let you use standard
image processing formulas or create your own formulas. The menu
bar at the top gives you fast access to many formulas. Note that the
current formula simply reads ‘INPUT1.’ (You will learn more about
formulas later.)
2. From the Ratios menu, select Landsat TM NDVI.
A new formula replaces the original one, and its description appears
at the top. (This formula is called the Normalized Difference
Vegetation Index, or NDVI. It uses information in bands 3 (red) and
4 (near infrared) of the Landsat image to highlight information on
vegetation location and abundance.)
All data is initially displayed as very dark shades of gray in the
grayscale lookup table because the formula processing produces a
narrow range of data values (-1 to +1). You will now enhance the
image to increase its contrast.
3. Click the Close button to close the Formula Editor dialog.
Adjust the image contrast
1. In the Algorithm window, click on the Layer tab and then click on
the right-hand Edit Transform Limits
button (there are two,
choose the one right of the Formula button).
Handling images
43
The Transform dialog box opens. Note that the field Actual Input
Limits at the bottom shows a data range of about -1 to +0.6. This is
the range of data values produced after the raw Landsat image data
was processed through the NDVI formula. You need to tell
ER Mapper to map the shades of gray in the lookup table to this
range instead of the 0-255 default data range currently shown along
the X or horizontal axis of the histogram.
2. From the Limits menu, select Limits to Actual.
The X axis data range changes to match the -0.8 to +0.6 limits of
the data after the NDVI formula processing.
ER Mapper renders the image again, this time with enhanced
contrast. In addition, a histogram showing the relative frequency of
data values for the processed image appears in the center of the
Transform dialog.
Areas of vegetation in the image are highlighted in light gray or
white, and areas with little or no vegetation (such as water) appear
very dark. You will increase the contrast between the light and dark
areas even further.
3. On the Transform dialog, click the Create autoclip transform
button.
Contrast between the light and dark areas further increases. The
lightest shades (densely vegetated areas) are now white and darkest
shades (non-vegetated areas) are black, making the patterns of
vegetation easier to interpret.
4. Click the Close button to close the Transform dialog box.
You will learn more about histograms, data ranges and contrast
enhancements later.
3: Labeling and
saving the
algorithm
Objectives
Learn to specify description labels, titles, and comments for an algorithm, and save the
algorithm processing steps to a file on disk for later use.
Enter a description for
the Pseudocolor layer
1. In the Algorithm window, on the left side of the data structure
highlight the layer and click on the description with the Pseudo
Layer.
The pointer turns into a text cursor, indicating that the area is a text
field.
44
Handling images
2. Type the text NDVI in the text field, then press the Enter or Return
key on your keyboard.
This text now becomes a visual description for the layer.
Layer descriptions are also used to specify labels for bands when
you write an image to disk or save it as a Virtual Dataset. You
will learn about this later.
Enter a description for
the surface
1. In the Algorithm window, on the left side of the data structure
highlight the surface and click on the "[Ps]: Default Surface"
description.
The pointer turns into a text cursor, indicating that the area is a text
field.
2. Type the text Surface 1 in the text field, then press the Enter or
Return key on your keyboard.
This text now becomes a visual description for the surface. Note that
the “[Ps]:” prefix remains, indicating that the surface Color Mode is
Pseudocolor.
Enter a description for
the entire algorithm
1. In the Algorithm window, select the text in the Description text
field (it currently reads ‘No Description’).
(To select the text, either drag through it, or triple-click to select the
entire line.)
2. Type the following text, then press Enter or Return on your
keyboard:
San Diego vegetation index
This text now becomes a brief description for the entire algorithm.
Save the processing steps
to an algorithm file on
disk
1. From the File menu (on the main menu), select Save As....
The Save As... file chooser dialog box appears.
2. In the Files of Type: field, select ER Mapper Algorithm (.alg).
3. From the Directories menu, select the path ending with the text
\examples. (The portion of the path name preceding it is specific to
your site.)
4. Double-click on the directory named Miscellaneous to open it.
Handling images
45
5. Double-click on the directory named Tutorial to open it.
6. In the Save As: text field, click to place the cursor, then type in a
name for the algorithm file. Use your initials at the beginning,
followed by the text Landsat_NDVI, and separate each word with
an underscore (_). For example, if your initials are JC, type in the
name:
JC_Landsat_NDVI
7. Click the Apply button to save the algorithm and leave the dialog
open.
Your Landsat NDVI algorithm is now saved to an algorithm file on
disk.
4: Reloading and
viewing the
algorithm
Objectives
Learn to reload and display the algorithm you just created, and to view the text file on
disk that defines the algorithm processing steps.
Open a second image
window
1. On the Standard toolbar (on the main menu), click on the New
button.
ER Mapper opens a new image window (this is a shortcut for
selecting New from the File menu). Drag the new window to the
lower left part of the screen (so you can see all or part of the other
image window).
Open the processing
algorithm you created
earlier
1. On the Standard toolbar, click on the Open
button.
The Open file chooser appears. (This is a shortcut for selecting
Open... from the File menu.)
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the directory named ‘Miscellaneous’ to open it.
4. Double-click on the directory named ‘Tutorial’ to open it.
Your Landsat NDVI algorithm should appear in the list.
5. Click once on your algorithm name to highlight it (do not double-
click).
46
Handling images
6. Click the Apply button to load and process the algorithm without
closing the Open dialog box.
ER Mapper runs the algorithm and displays the processed Landsat
image in the image window. It should look identical to the other
image since they both use the same algorithm and input image.
Add comments to the
algorithm
1. Click the Comments... button.
A dialog box appears showing the algorithm file name with a text
area for you to type comments about your algorithm. The cursor is
already active in the upper-left corner.
2. Click Cancel on the Save Algorithm dialog to close it (you do not
need it).
3. In the Comments dialog, type the following information about your
algorithm:
This algorithm uses the Normalized Difference
Vegetation
Index (NDVI) formula to highlight vegetation in a
Landsat
TM image of San Diego. Areas with abundant vegetation
appear as lighter shades of gray.
4. Click the OK button to save your comments with the algorithm.
5. Click Cancel on the Save Algorithm dialog to close it.
(If you accidentally click OK, click Cancel when asked to overwrite
the file. Otherwise your comments will not be saved with the
algorithm file.)
View the algorithm
comments
1. On the Open dialog, click the Comments... button.
A dialog box opens showing the comments you entered for your
algorithm. These comments can be very helpful to others who use or
display your algorithm, and they are a good way to document the
procedures you used to create it.
2. Click Cancel to close the comments dialog box.
5: Viewing the
image in 3D
perspective
Objectives
Handling images
Learn to create a 3D perspective view of the vegetation index image by adding a Height
layer containing a digital elevation image.
47
About 3D perspective
viewing
Up until now you have viewed your images using conventional 2D
planimetric views. ER Mapper makes it very easy to view images in
3D perspective by simply adding a height (or elevation) component
to your algorithm. The following is a very simple introduction to the
3D viewing features, and you will learn more about them in later
chapters.
Display the vegetation
image in brown and green
1. In the Algorithm dialog, select the Surface tab.
2. From the Color Table drop-down list, select brown_green.
ER Mapper redisplays the image. Areas with no or little vegetation
(such as ocean) display as brown, and vegetated areas like parks
and canyons are bright green.
3. In the Algorithm dialog, select the Layer tab again.
Add a Height layer to the
algorithm
1. On the Algorithm dialog, open the Edit menu, select Add Raster
Layer, then select Height.
A second layer named ‘Height Layer’ is added to the algorithm.
Height layers are only valid in 3D view modes, so the layer is
currently inactive (crossed out).
Load a digital elevation
image into the Height
layer
1. With the Height layer selected, click the Load Dataset
button
in the process diagram.
The Raster Dataset dialog opens.
2. From the Directories menu (on the Raster Dataset dialog), select
the path ending with \examples.
3. Open the Shared_Data directory, then double-click on the image
Digital_Terrain_Model.ers to load it.
The digital elevation model (DEM) image is loaded into the Height
layer.
Select 3D perspective
View Mode to view the
image in 3D
1. From the View Mode menu (on the Algorithm dialog), select 3D
perspective.
48
Handling images
ER Mapper displays a message that the image is being processed,
then displays a 3D perspective view of the image. The message
“Regenerating Terrain” appears in the image window as ER Mapper
performs iterations to increase the resolution (detail) in the 3D
image.
The right-hand panel in the Algorithm dialog now has two additional
tabs–3D View and 3D Properties. These contain controls
specifically for 3D viewing of images.
Turn off the 3D lighting
option
1. In the Algorithm dialog, select the 3D View tab.
2. Turn off the Lighting option button.
The image redisplays without artificial lighting. (Although this is
sometimes desirable, it can also obscure subtle features.)
Change the perspective
viewing angle
1. Click on the Hand Tool
button on the Standard toolbar, if it is
not already selected.
2. Point to the lower part of the 3D image, and drag down slightly to tilt
the 3D view (see following diagram).
point to this area and drag down slightly to tilt 3D model down
The 3D image tilts downward, so you are now looking more from an
overhead viewpoint. You can use the mouse to manipulate the
viewpoint, zoom in and out, rotate the image, and other controls
(discussed in detail later).
This is a simple 3D algorithm that lets you quickly see the
relationship between terrain features and vegetation in the San
Diego area. You can see, for example, that natural vegetation still
occurs in the many of the narrow canyons and hillsides next to
developed areas.
Handling images
49
Select 2D View Mode to
view the image in 2D
again
1. From the View Mode menu in the Algorithm window, select
Normal.
ER Mapper redisplays the image in a two-dimensional planimetric
view again.
This 3D exercise was a simple introduction to show how easy it
can be to view data in 3D perspective in ER Mapper. You will
learn more about the 3D capabilities and controls later.
Close the image and
Algorithm dialog
windows
1. Close the image window using the window system controls:
•
Click the
Close button in the upper-right window corner.
The window closes and disappears from the screen.
2. Click Close on the Algorithm dialog.
Only the ER Mapper main menu is now open.
What you
learned...
50
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Load a new image and choose which bands to display
•
Use the Algorithm dialog to define a processing algorithm
•
Change the color lookup table for an image
•
Add a formula to an algorithm
•
Add text labels and comments to an algorithm
•
Save the processing algorithm to disk
•
Reload and view the saved algorithm
•
Add a Height layer to view the image in 3D perspective
Handling images
Working with data layers
This chapter introduces you to the concept of data layers in
ER Mapper, and gives you practice using them. You will learn to load
data into layers, turn layers on and off, specify layer priority during
processing, and add, move, and delete data layers in an algorithm.
This chapter focuses on the use of raster data layers for
displaying and manipulating images. Use of vector layer types
for displaying GIS data and annotation are covered later in this
manual.
About data layers
In ER Mapper, you build your image display by creating one or more
‘layers’ of data in the Algorithm window. The various data layers
combine to create a final image on your screen display or output to
your hardcopy device.
To view process stream diagram of a layer click on the Layer Tab and
select the layer from the left side of the Algorithm window. Each
layer in an algorithm can have different processing and use different
image datasets. The simple algorithm you developed in Chapter 7
had only one layer (a Pseudocolor layer), but other types of
algorithms can have several data layers. For example, an image
displayed in RGB (red-green-blue) has three data layers–one for the
red image component, one for the green, and one for the blue.
Layers can also contain other types of data that you want to overlay
on your image, such as GIS vector or tabular data, and annotation
or map composition objects.
Each layer in your algorithm can be manipulated independently from
the others using the process stream buttons associated with that
layer. This flexibility is one of the key features in ER Mapper that
makes it easy to build and fine tune complex image processing
algorithms.
Typically, you build an algorithm by first defining one or more layers
to display your raster image data, such as satellite images or
digitized aerial photos. Then you can add additional layers to display
vector data (such as a road network), tabular data (such as sample
site locations), and layers to annotate your image with text,
coordinate grids, and so on.
Layer controls
Working with data layers
If you click on the layer tab, the process diagram of the current layer
appears. Each layer in an algorithm has a common set of information
and controls provided on the layer itself:
51
Load image dataset
Select image bands
Use formula
Open filter
editor
Transform Adjust contrast
Apply shaded
relief
To turn a layer off, click on the Turn On/Off button
on the
Algorithm window or click the right hand mouse button on the layer
to display the Short-cut Menu and select Turn Off. .
About color
modes
ER Mapper uses a concept called the “Color Mode” that defines the
manner in which layers containing raster data are displayed. To
define a particular type of image display, you choose the appropriate
types of layers and the appropriate Color Mode. Color Mode is located
in the Surface tab on the Algorithm window. Click on the Surface
tab and you will see the Color Mode, the Color Table and the
Transparency(%) with a slide button.
Color Mode options (in
Surface Tab)
ER Mapper provides three Color Mode options in Surface Tab, and
each is designed to display and manipulate raster image data in a
different way. The Color Mode setting must usually correspond with
the type of data layers you are using. For example, if you are
working with Pseudocolor layers, your Color Mode must be set to
Pseudocolor. The three Color Modes are:
Color Mode
Function
Pseudocolor
Designed to display a single layer of raster data; image colors are
controlled by the current Lookup Table setting.
Red Green Blue
Designed to display raster data in Red Green Blue (RGB) color
space. The image colors are built using separate layers for the red,
green, and blue color planes (or color guns) of the computer display.
Hue Saturation Intensity
Designed to display raster data in Hue Saturation Intensity (HSI)
color space. The image colors are built using separate layers for hue
(color), saturation (color purity), and intensity (color brightness).
About data layers
52
ER Mapper provides several types of data layers, each designed to
display a particular format of data (raster, vector, tabular), or
display raster image data in a particular way. In general, there are
two types of layers:
Working with data layers
Raster layer types
•
Raster layers display image or pixel datasets, and the displayed
image is often the result of combining two or more types of raster
layers (for example, red, green, and blue).
•
Vector layers display GIS, line, tabular (point), and map
composition data, and always cover raster data underneath them
where there is overlap.
Many of the raster layer types are only valid with a certain Color
Mode setting. If the layer is not valid with the current Color Mode,
ER Mapper automatically dims that layer on the Algorithm window
and does not use it during processing. The types of raster layers and
the valid Color Modes associated with them are listed in the table
below:
Raster layer
Function
Valid Color Modes
Pseudocolor
Displays raster data, colors are controlled by the current
Lookup Table.
Pseudocolor
Red
Displays raster data in the display’s red color channel.
Red Green Blue
Green
Displays raster data in the display’s green color channel.
Red Green Blue
Blue
Displays raster data in the display’s blue color channel.
Red Green Blue
Hue
Displays raster data; controls the “color” component (red, Hue Saturation
yellow, green, etc.) of the displayed image.
Intensity
Saturation
Displays raster data; controls the “color purity”
Hue Saturation
component (pastel or pure colors) of the displayed image. Intensity
Intensity
Displays raster data; controls the “brightness” component all
(lightness or darkness) of the displayed image.
Height
Controls the third dimension elevation (or “z-value”) of an all
image viewed in 3-D perspective.
Class Display
Displays a raster image created with ER Mapper’s
Supervised or Unsupervised Classification functions.
all
Classification
Displays a solid color thematic overlay generated from
raster data over other raster overlays.
all
You can quickly change any raster layer in an algorithm from one
type to another by using the Layer Type drop-down list from
Edit/Change Raster Layer menu or from the Short-Cut menu
which appears after clicking the right mouse button on the
highlighted layer.
Working with data layers
53
Vector layer types
Vector layers are used to display map annotation and data from
external products or vector file formats. All vector layers are always
drawn on top of any raster layers, regardless of their position among
other layers in the Algorithm window. Vector layers are not affected
by the Color Mode setting (those apply to raster layers only). The
following are the main types of vector layers:
Vector layer type
Function
Annotation/Map
Composition
Create color annotation (lines, circles, text, etc.) and map composition
objects (scale bars, north arrows, etc.). Also used to display files in
ER Mapper vector format (with an .erv file extension).
Region overlay
Define region polygons (areas of interest) for a raster image, or display
existing regions and names.
ARC/INFO overlay
Display, edit, and save vector data stored in the native “coverage” format
of the ARC/INFO GIS software.
Dynamic Links
Display vector or tabular data from other software products or file formats
such as DXF or PostScript.
There are additional types of vector layers used less frequently;
these are not covered in detail in this manual. You can add any
of the Vector layer types from the drop down list which appears
after clicking the Edit/Add Vector layer menu.
Selecting and Modifying
Data Layers
To modify a data layer, you must first select it by clicking on it. A
shaded box then appears surrounding the layer to indicate that it is
selected. You must first select a layer before you can load a new
image dataset into it or modify it’s process stream.
Note that a layer may become inactive if you change the Color Mode
in the Surface Tab to an option that is not valid for that layer. When
a layer becomes inactive, its text appears dimmed or “grayed out”
on the Algorithms window. For example, if you change the Color
Mode to Red Green Blue, any Pseudocolor overlays become inactive
since Pseudocolor overlays are only valid with a Pseudocolor Color
Mode. Inactive layers are ignored during processing (similar to being
turned off).
Hands-on
exercises
These exercises give you practice using and manipulating raster data
layers in ER Mapper. Understanding how to work with layers is an
important step in understanding how to build and use algorithms.
What you will learn... After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
54
•
Turn data layers on and off
•
Load an image into one or several raster layers
Working with data layers
Before you begin...
•
Add, delete, and move layers
•
Change a raster layer from one type to another
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Turning layers
on and off
Objectives
Learn to turn data layers on to include them in processing and off to exclude them from
processing. Also learn how the status of layers can change if the Color Mode changes.
Open an image window
and display a mosaic
algorithm
1. From the File menu, select Open....
An image window and the Open file chooser dialog box appear.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the directory named Functions_And_Features.
4. Double-click on the directory named Data_Mosaic.
5. Double-click on the algorithm named
Interactive_mosaic_of_4_datasets.alg.
ER Mapper opens and displays the algorithm.
This algorithm displays a mosaic of four separate image datasets
that partially overlap with each other. Each image is loaded into its
own Pseudocolor data layer, so it can be controlled independently
from the other images. (You will learn more about creating mosaics
of two or more images later.)
Open the Algorithm
window to view the data
layers
1. From the View menu, select Algorithm....
The Algorithm window appears showing four Pseudocolor data
layers.
2. If needed, make the Algorithm window taller until all four layers are
clearly visible at once. (Drag the top window border upward.)
Working with data layers
55
Turn overlays off to
exclude them from
processing
1. In the Algorithm window, with the Layer tab selected, click on the
left side of the layer containing the image named Mosaic_TM to
select it.
A dark border surrounds the layer, indicating that it is selected.
2. Click your right mouse button on the highlighted layer and the
Short-Cut menu will appear. Turn the Mosaic_TM layer off by
selecting the Turn Off option from the Short-Cut menu.
The layer is now turned off, so ER Mapper will ignore it during
processing.
ER Mapper reprocesses the mosaic algorithm so that the data in the
upper-right portion of the image window (a portion of a Landsat TM
image) is not displayed. Since the layer containing the ‘Mosaic_TM’
image is turned off, its data no longer appears as part of the mosaic.
3. In the Algorithm window, click on the left side of the layer
containing the image named ‘Mosaic_XS’ to select it.
4. Click the right mouse button on the selected layer and turn off the
‘Mosaic_XS’ data layer from the Short-Cut menu.
This time the data in the lower portion of the mosaic (a portion of a
SPOT XS image) does not display since its layer is turned off.
Turn overlays on to
include them in
processing
1. In the Algorithm window, click to select the layer containing the
image named ‘Mosaic_TM.’
2. Turn the ‘Mosaic_TM’ layer on again (click the right mouse button on
the selected layer and select Turn On, from the Short-Cut menu).
The Landsat TM satellite data again displays in the upper-right
portion of the image window since its layer is now turned on.
3. Click to select the layer containing the image named ‘Mosaic_XS.’
4. Turn the ‘Mosaic_XS’ layer on again.
The SPOT XS satellite image again displays in the lower portion of
the mosaic.
Change the Color Mode to
see how it affects layers
1. In the Algorithm window, from the Surface Tab select Red Green
Blue from the Color Mode drop-down list.
56
Working with data layers
All four Pseudocolor layers display a hatched pattern (diagonal
lines), indicating that they are no longer valid with the current Color
Mode.
Whenever raster layers are not valid with the current Color
Mode in the Surface Tab, they become hatched (inactive) on
the Algorithm window. ER Mapper treats inactive layers as if
they are turned off.
2. On the Surface Tab from the Color Mode drop-down list, select
Pseudocolor.
ER Mapper reprocesses the algorithm and displays the image with all
the layers active.
2: Loading data
into layers
Objectives
Learn to load an image into a particular layer or set of layers in an algorithm. Also
understand use of the OK, Apply, OK this layer only, and Apply this layer only
buttons on the Raster Dataset file chooser dialog box.
Open a Red Green Blue
(RGB) algorithm
1. On the ER Mapper Standard toolbar, click the Load
button.
The Open file chooser appears.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the directory named ‘Data_Types’
4. Double-click on the directory named ‘Landsat_TM.’
5. Double-click on the algorithm named ‘RGB_432.alg.’
Working with data layers
57
This algorithm displays bands 4, 3, and 2 of a 1985 Landsat TM
satellite image of central San Diego as an RGB color composite
image. Water areas appear dark, and shades of red indicate
vegetation.
Load a new image into all
three layers
1. With the ‘Layer’ tab selected, click on the Load Dataset
button
in the process stream diagram.
The Raster Dataset file chooser appears. Note that this dialog has
OK this layer only and Apply this layer only buttons in addition
to the OK and Apply buttons you see on all other file chooser
dialogs.
58
Working with data layers
current directory
click to move up
and down one
directory level
selected .ers file
file types
(.ers, .alg, hdr
.bmp, .tif, .sid)
view information
or edit image
header file
click to view comments
load into selected
layer only, keep
dialog box open
load into selected
layer only, close
dialog box
load into layers with same
image, close dialog box
load into all layers with same image,
keep dialog open
Notice that the Raster Dataset file chooser shows files with .ers
extensions. You can change file types (.ers, .alg, .hdr, .bmp, .tif,
.sid) from the drop down list of the button of file types. Typically you
load images into raster layers for processing, but you can also load
an algorithm and use it as if it were an image dataset.
Load a new image into all
three layers
1. From the Directories menu, select the path ending with the text
\examples.
2. Double-click on the directory named Shared_Data.
3. Click once on the image named Landsat_TM_year_1991.ers.
4. Click the Apply button.
ER Mapper loads the 1991 Landsat image into all three layers. Since
all three layers previously contained the same image (the 1985
Landsat image), Apply replaced the image in all three layers at
once.
Working with data layers
59
Load a new image into
only one layer
1. Click on the Green layer to select it.
2. In the scroll list on the Raster Dataset dialog, click on the image
named Landsat_TM_year_1985.ers to select it.
3. Click the Apply this layer only button.
ER Mapper loads the 1985 Landsat image into only the Green layer.
4. Click on the Blue layer to select it.
5. In the Raster Dataset dialog, click on the image named
Landsat_TM_year_1985.ers to select it.
6. Click the Apply this layer only button.
ER Mapper loads the 1985 Landsat image into the Blue layer.
The OK and OK this layer only buttons have the same function
as the Apply and Apply this layer only buttons, but they close
the dialog after performing the operation (while the others leave
it open). Double-clicking on an image or algorithm name in the
scroll list has the same effect as clicking OK.
3: Adding and
changing layers
Objectives
Learn to delete layers from an algorithm, add new layers, and move layers by using
buttons and the mouse. Also, learn to change a raster layer from one type to another
type (green to blue for example).
Open a new RGB
algorithm
1. On the ER Mapper Standard toolbar, click the Load
button.
The Open file chooser appears.
2. From the Directories menu, select the path ending with the text
\examples
3. Double-click on the directory named Data_Types.
4. Double-click on the directory named SPOT_XS.
5. Double-click on the algorithm named SPOT_XS_rgb_321.alg.
60
Working with data layers
This algorithm displays a SPOT XS (multispectral) satellite image of
San Diego as an RGB color composite of bands 3, 2 and 1. (These
bands are similar to Landsat TM’s bands 4, 3 and 2 but are imaged
at higher resolution.)
Change the order of
layers using buttons
1. On the Algorithm window, click on the ‘Green’ layer to select it.
2. Click the Move Up button
.
The Green layer moves up one level to the top of the layer list.
3. Click on the ‘Blue’ layer to select it.
4. Click the Move Down button
.
The Blue layer moves to the bottom of the layer list.
Change the order of
layers by dragging
1. Point to any part of the Red layer, then drag down below the Blue
layer and release.
The Red layer moves down to the bottom of the layer list.
2. Drag the Green layer to move it below the Red layer.
It is often easier to move or reposition layers by dragging them
rather than using the Move Up and Move Down buttons.
The order of layers can be important when building image
mosaic algorithms that display more than one image (it sets the
display priority of images where there is overlap, those on top
having the highest priority). In this case, changing the order of
the layers has no effect on the image display.
Delete the Blue and Green
layers
1. Click on the Blue layer to select it.
2. Click the Cut button
to delete the Blue layer from the list.
You can also cut the layer by selecting the cut option from the
Edit menu or on the computer keyboard simply press and hold
the Control button and type X “Ctrl+X”.
3. Click on the Green layer to select it.
Working with data layers
61
4. Click the Cut button
to delete the Green layer from the list.
ER Mapper displays only the red component of the image (SPOT
band 3 in this case) because the Blue and Green layers of the
algorithm were deleted.
Restore the Green layer
by adding one and
loading the image
1. From the Edit/Add Raster Layer drop-down menu, select Green.
A new Green layer is added to the algorithm. The new layer has no
image loaded yet (indicated by No Dataset), so it is turned off.
2. In the process stream diagram, click the Load Dataset
button.
The Raster Dataset file chooser appears.
3. From the Directories menu, select the path ending with the text
\examples.
4. Double-click on the directory named Shared_Data.
5. Click on the image named SPOT_XS.ers. to select it, then click OK
to load it and close the dialog.
ER Mapper loads the image into the new Green layer and turns it on.
Also note that band 1 is loaded by default in the process stream
diagram.
If you had wanted to load this image into only the Green layer,
you could have clicked OK this layer only or Apply this layer
only.
6. From the Band Selection
drop-down list, select
B2:0.645_um.
You have now created a new Green layer that contains the same
image and band as the original green layer you deleted earlier.
Restore the Blue layer by
duplicating the Green
layer
1. With the Green layer still selected, click the Duplicate
button.
A second Green layer is added below the first one. The second Green
layer is an exact copy of the first one, so it already has the ‘SPOT_XS’
image loaded.
62
Working with data layers
2. Click your right mouse button on the highlighted Green layer and the
Short-Cut menu will appear. From the Short-Cut menu, select
Blue.
The Green layer changes to a Blue layer.
3. From the Band Selection
drop-down list, select
B1:0.545_um.
The new Blue layer is now correctly set to display band 1 of the SPOT
image.
When manipulating multiple layers, duplicating an existing layer
with the desired image and changing its type is usually faster
than adding a new layer and loading the desired image.
Note that the colors look slightly different to those in the original
algorithm you opened at the start of this section. You need to adjust
the transforms of the new Green and Blue layers.
Adjust the transforms of
the Green and Blue layers
1. Select the Green layer, then click on the right-hand Edit Transform
Limits
button in its process stream diagram.
The Transform dialog box opens.
2. From the Limits menu, select Limits to Actual.
The X axis (input) data range changes to match limits of the band 2
data.
3. Click the Move to next blue layer
button on the Transform
dialog.
ER Mapper automatically selects the Blue layer and displays its
histogram. (You will learn more about moving between histograms
of layers later.)
4. From the Limits menu, select Limits to Actual.
ER Mapper reprocesses the algorithm using the actual data limits as
the X (input) axis limits.
5. On the Transform dialog, click the Create autoclip transform
button.
ER Mapper changes the transform line on the histogram to increase
contrast of the blue data layer and redisplays the composite image
automatically.
Working with data layers
63
6. Click the Move to next green layer
button on the Transform
dialog.
ER Mapper automatically selects the Green layer and displays its
histogram.
7. Click the Create autoclip transform
button.
ER Mapper changes the transform line to increase contrast of the
green data layer and redisplays the image.
8. Click the Close button on the Transform dialog to close it.
Close all image windows
and dialog boxes
1. Close all image windows using the window system controls.
2. Select Close from the window control-menu.
3. Click Close on the Algorithm window to close it.
Only the ER Mapper main menu should be open on the screen.
What you learned
64
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Turn data layers on and off
•
Load an image into one or several raster layers
•
Add, delete, and move layers
•
Change a raster layer from one type to another
Working with data layers
Viewing image data values
This chapter shows you the options ER Mapper provides for viewing
image data values and coordinate locations. These include cell
values, neighborhoods, signatures, traverse extraction, and
scattergrams. You also learn how to measure distances between two
points on an image.
About viewing
data values
Hands-on
exercises
Viewing image data values is one of the fundamental ways to assess
data quality and the particular characteristics of features in an
image. Options for viewing data values and geographic locations in
ER Mapper include:
•
Cell values: The data value associated with each cell or pixel in
•
Neighborhoods: An array of data values surrounding a pixel.
•
Signatures: The data values of a pixel in all bands shown in a line
graph format.
•
Traverse extraction: A profile of data values occurring along a
line or polygon drawn on the image.
•
Scattergrams: An X-Y plot showing the relationship between data
values in two bands of an image.
•
Histograms: A plot showing the range of data values on the X
the image, or the data values of that cell in each band of a multiband image.
axis and their relative frequency on the Y axis.
These exercises show you various ways of viewing data values,
coordinate locations, and geographic distances between two points
on an image.
What you will learn... After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
Before you begin...
•
View image data values in text format.
•
View image data values in multiple bands as a signature.
•
View image data values in multiple bands along a profile line.
•
View two bands of image data values as a scattergram.
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
Viewing image data values
65
1: Viewing values
and signatures
Learn to view image data values in a text format, neighborhood format, and signature
(line graph) format.
Objectives
Open and display an RGB
algorithm
1. From the File menu, select Open....
An image window and the Open file chooser dialog box appear.
2. Double-click on the directory named
\examples\Data_Types\Landsat_TM to open it.
3. Double-click on the algorithm named RGB_741.alg.
This algorithm displays bands 7, 4, and 1 of the San Diego Landsat
image as an RGB color composite image.
View cell values in the
image for all bands
1. From the View menu, select Cell Values Profile....
The Cell Values Profile dialog box appears. Drag it by its title bar
next to the image window. This dialog has three display windows,
any of which can be turned on or off at any time.
Signature
window
Neighbors
window
option to turn
window on/off
drag to resize
window areas
Values
window
2. By default, the Values option is selected. (If this has been changed,
turn on Values and turn off Signature and Neighbors.)
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Viewing image data values
3. On the main menu, click the Set Pointer mode
toolbar button.
Set Pointer mode tells ER Mapper that you want to use the mouse
pointer to view data values. (The other modes set the pointer for use
as a zoom and pan tool.)
4. Point inside the image window, and drag the mouse pointer through
the image (or just click on any pixel).
The Cell Values Profile dialog displays the data values in all seven
bands in the Landsat image for the current cell (pixel) location in the
image. The data values are updated as you drag the mouse to new
locations.
(If all seven bands are not shown, simply drag the lower edge of the
dialog box to make it slightly larger.)
View a neighborhood of
cell values
1. In the Cell Values Profile dialog, turn on the Neighbors option.
A second window is added to the Cell Values Profile dialog, with a
drop-down menu to select an image band.
2. Point inside the image window, and drag the mouse pointer through
the image (or just click on any pixel).
A three-by-three neighborhood of cell values displays as you drag
the mouse. The center pixel in the three-by-three array is the
current pixel, and the surrounding eight pixels are its neighbors. This
feature is useful for viewing the local variance or texture in various
parts of an image.
3. From the Band drop-down list, select B4:0.83_um then drag again
in the image.
The data values for band 4 of the Landsat image display in the threeby-three neighborhood.
View a signature of cell
values for various
features
1. In the Cell Values Profile dialog, turn on the Signature option.
A third window is added to the Cell Values Profile dialog, with a row
of color buttons on top.
2. Make the Signature window larger by resizing the entire dialog box,
or by turning off the Neighbors option.
3. Click on the green color button above the Signature window.
4. Point to the image window, and drag through one of the green areas
on the image (natural and man-made vegetation).
Viewing image data values
67
The data values in all seven bands display in a line graph format
(sometimes called a signature) in green. The tick marks at the
bottom indicate the number of bands in the image. In this case, you
are using Landsat TM data, so you see the value in each of the seven
bands as an individual measurement on the graph.
5. Click on the yellow color button above the Signature field.
6. Point to the image window, and click or drag on one of the bright
white areas of the image (building roofs or barren land areas).
A new signature for the bright areas appears in yellow.
7. Click on the green color button again to clear the signature.
When you click on a color button a second time, the existing
signature (colored line) in the window is removed.
8. Point to the image window, and drag through a green, vegetated
area again to display a new signature.
View an average
signature for a feature
1. Click on the blue color button.
2. Turn on the Average option.
3. Point to the image window, and drag through one of the dark ocean
areas surrounding the island near the bottom.
A third new signature appears in blue. Notice that the signature line
gets thicker as you drag this time.
When using Average, the signature is an accumulated average of all
the data values over the area where you dragged. You can add to the
average signature by continuing to drag. This allows you to view the
average signature over a broad feature area (instead of a single pixel
at a time).
4. Click the Close button on the Cell Values Profile dialog box to close
it.
2: Viewing
locations and
distances
Objectives
Learn to view the geographic location of features in a image, and to measure the
distance between two points in an image.
View geographic
coordinates in the image
1. From the View menu, select Cell Coordinate....
68
Viewing image data values
The Cell Coordinates dialog appears. Drag it next to the image
window.
The upper three fields of this dialog show the location of the current
pixel in image column (X) and row (Y) coordinates, and the
Eastings/Northings and Latitude/Longitude coordinate systems.
2. Point to the image window, and drag the pointer through the image.
The image and geographic location of the current cell appear, and
are updated as you drag the mouse.
The Easting Northing and Latitude Longitude fields only display
values if the image is registered to a map projection.
View distances between
points in the image
The lower three fields of the Cell Coordinate dialog show distance
between the point where you first depress the mouse button and the
point where you release it. Distances are shown as Imperial distance
(feet and miles), Metric distance (meters and kilometers), and
Dataset distance (number of pixels in the X and Y directions).
1. Point to the image window, and click on any point in the image.
The Imperial, Metric, and Dataset distance fields are cleared to zero
values.
2. Pick out two features in the image, then drag the mouse between
them.
This distance between those two points is displayed when you
release the mouse button. Measuring the distance between two
points is called mensuration.
3. Click the Close button on the Cell Coordinates dialog box to close
it.
3: Viewing
traverse profiles
Objectives
Learn to view image data values for multiple bands as a profile along a line or polygon
draw through the image (called traverse extraction).
Set up to draw traverse
profile lines
1. From the View menu, select Traverse....
New Map Composition and Traverse dialog boxes appear.
2. On the New Map Composition dialog, be sure the Vector File
option is selected, then click OK.
Viewing image data values
69
An ER Mapper warning dialog and the annotation Tools palette
dialog appear. You will use the vector annotation tools to draw
traverse lines on the image.
3. Click Close on the ER Mapper warning dialog to close it. (When
using annotation tools for other purposes the default Fixed Page
mode is not recommended, but it is fine for this exercise.)
Draw a traverse line on
the image
1. On the Tools dialog, click the Annotation: Poly Line
button.
2. Inside the image window, define a straight line by clicking once at
the start point, click once at the end point, then double-click to end
the line definition.
A profile line appears inside the ER Mapper Traverse dialog. This
line displays the amplitude or change in the values of pixels
underneath the traverse line you drew. By default, values for image
dataset band 1 are shown as a black profile line.
band/color
legend
scale of
dataset
values
graphical
plot of change
in values
along traverse
location
of profile
View profiles for 3 image
dataset bands
1. On the ER Mapper Traverse dialog, click the Bands:
button.
The Traverse Band Selection dialog appears.
2. Press the Ctrl key on your keyboard, then click on bands 1, 4 and 7
in the list to select them.
3. Click OK on the Traverse Band Selection dialog.
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Viewing image data values
Profiles for all three bands appear in the ER Mapper Traverse
dialog, with a legend in the upper-right indicating the line color
assigned to each band. This type of display allows you to clearly see
the relationship between data values in the three bands. (In this case
you are viewing data values for the same bands displayed in the RGB
image (7, 4 and 1), but you could also view profiles for bands not
used to display the image.)
Draw a second traverse
line on the image
1. Inside the image window, define a second line in a different area by
again clicking once at the start point, click once at the end point,
then double-click to end the line definition.
The three profile lines appears inside the ER Mapper Traverse
dialog update to show the pixel values under the new line. You can
draw as many different traverse lines on the image as you desire.
Alternate between the two traverse lines and
modify them
1
On the annotation Tools dialog, click the Select and Edit
Points Mode
button.
2. Inside the image window, click on the first traverse line you drew.
The line becomes selected and it’s corresponding profiles again
appear in the ER Mapper Traverse dialog. You can view the profiles
for any traverse line by simply selecting it as shown here.
3. On the annotation Tools dialog, click the Select and Move/Resize
Mode
button.
4. Inside the image window, click once on one of the endpoints of the
currently selected traverse line (the point become reverse
highlighted).
5. Point to the reverse highlighted end point, and drag it to a new
location.
When you release the mouse button, the revised line appears on the
image and it’s corresponding profiles are updated in the ER Mapper
Traverse dialog. You can modify the location and length of any
traverse line by following these steps.
6. Revise one of your lines so it traverses across one of the dark ocean
areas in the lower part of the image.
Notice the strong dip in data values in all three bands where the lines
crosses the ocean. This is typical of Landsat TM data because water
generally has much lower reflectance in these wavelengths of light
than land areas.
Viewing image data values
71
7. Click Close on the ER Mapper Traverse dialog to close it, then click
Close on the Tools dialog to close it also.
8. When asked to save the current annotation, click No.
If desired, you could save the current annotation layer and
reload it later, and you can also save the traverse profiles to an
XYZ format dataset on disk for export to other analysis software
if desired. See the online ER Mapper User Guide for more
information.
4: Viewing image
scattergrams
Objectives
Learn to view the relationship between image data values in two bands as a
two-dimensional plot called a scattergram (or scatter diagram).
A scattergram allows you to graphically see the correlation between the
digital numbers in two image bands. Values for one band are plotted
on the Y axis and the other on the X axis. These two digital numbers
locate each pixel in the two-dimensional measurement space of the
graph.
Open a Scattergram
dialog box
1. From the View menu, select Scattergrams....
The Scattergram dialog box and New Map Composition dialog
boxes open.
2. Click Cancel on the New Map Composition dialog to close it. (You
do not need it for this exercise.)
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Viewing image data values
The Scattergram dialog automatically references the image in the
active image window (‘Landsat_TM_year_1985’). You could choose
to view scattergrams for any other image, Virtual Dataset, or
algorithm as well.
By default, a new scattergram plots band 1 of the image on the X
(horizontal) axis and band 2 on the Y (vertical) axis, and the cluster
of points is shown using various colors inside the scattergram
window. The colors represent the accumulated frequency (or
“density”) of data values in both bands. Areas of the scattergram
with the highest densities of points are shown in colors in the upper
part of the color bar (red and yellow), and low density areas in the
lower colors (blue and magenta). Typically, high density areas will
be a feature comprising a large number of pixels in both bands, such
as a large area of water.
Change the image band
combination
In the scattergram for bands 1 and 2, notice that the data points are
tightly grouped. This indicates that there is a strong correlation
between the data contained in these two bands (both visible
wavelength bands), so they contain much redundant information.
1. In the Scattergram dialog, click the Setup... button.
The Scattergram Setup dialog opens to provide options for
changing image bands, defining regions, and other functions. Move
it so it does not cover the Scattergram dialog or image window.
Viewing image data values
73
select image bands
for scattergram
2. Click on the drop-down list for the Y Axis field, and select
B4:0.83_um.
ER Mapper redraws the scattergram, this time showing the data
values from band 4 on the Y axis.
3. Click the Limits to Actual button to set the X and Y axis limits to
the actual data ranges of bands 1 and 4.
The scattergram enlarges to fill the window. The wide spread of
points shows that the data in bands 1 and 4 are weakly correlated,
so they provide different types of information. (Band 4 records
reflectance in near infrared wavelengths.)
Change the axis limits to
“zoom in” on part of the
scattergram
Notice the small, dense grouping of points in the lower-left corner of
the scattergram (shown in cyan, green and red). This indicates that
there is a high frequency of data points in both bands in that area.
1. Point the mouse (without depressing it) at the areas surrounding the
dense grouping.
Directly above the scattergram window, ER Mapper displays the
position of the mouse pointer in the scattergram and data values in
both bands. The first value is the X axis (band 1) value, and the
second the Y axis (band 4) value.
To focus more on this area of the scattergram, you can use the
mouse to determine the approximate data limits of the dense
cluster, and then reset the X and Y axis limits to “zoom in” on it.
2. In the Scattergram Setup dialog, turn on the Defer Display
option. The Display button (unavailable before) is now active.
74
Viewing image data values
Defer Display tells ER Mapper to delay updating the scattergram
until you finish changing the desired options (the axis limits in this
case).
3. Edit the X (horizontal) axis maximum value to 120, and press Enter
or Return to validate.
4. Edit the Y (vertical) axis maximum value to 30, and press Enter or
Return.
5. Click the Display button.
ER Mapper redisplays the scattergram to “zoom in” on the dense
cluster, so you can more clearly see the detail.
6. In the Scattergram Setup dialog, click the Limits to Actual
button, then click Display again.
The scattergram zooms back out to the previous extents.
7. Turn off the Defer Display option.
8. Click Close on the Scattergram dialog to close it and the
Scattergram Setup dialog.
You will learn more about additional uses and options for
scattergrams in other parts of this manual.
Close all image windows
and dialog boxes
1. Close all image windows using the window system controls:
•
Select Close from the window control-menu.
2. Click Close on the Algorithm window to close it.
Only the ER Mapper main menu should be open on the screen.
What you learned
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
Viewing image data values
•
View image data values in text format
•
View image data values in multiple bands as a signature
•
View image data values in multiple bands along a profile line
•
View two bands of image data values as a scattergram
75
76
Viewing image data values
Enhancing image contrast
This chapter explains how to modify raster image data to enhance
contrast or color to improve visual interpretation. It introduces the
basic concepts associated with contrast enhancement and color
mapping, and gives you practice using ER Mapper’s Transform
options.
About contrast
enhancement
Adjusting image contrast (often called “contrast stretching”) is the
most fundamental and often-used enhancement operation in digital
image processing. The human eye is very good at interpreting spatial
attributes in an image and picking out subtle features. However, the
eye is poor at resolving such features when they are characterized
by very subtle differences in color or brightness. Contrast
enhancement techniques are useful for accentuating subtle
differences in data values to improve visual interpretation.
Contrast enhancement is called a “point operation” in image
processing because it applies a brightness or color transformation to
each pixel in the image independent of all other pixels. By adjusting
the “transform” that maps image data values to the display
brightness or colors in a lookup table, you can enhance (or “stretch”)
the contrast or highlight specific features to make your data easier
to interpret and analyze.
Two of the most common image display techniques are Pseudocolor
and Red Green Blue (RGB).
Displaying images with a
color lookup table
When displaying an image using a color lookup table (CLUT) (Color
Table menu on the Surface Tab in the Algorithm window), image
data values are mapped to specific colors or “slots” in a table. In this
case, changing the transform tells ER Mapper to adjust the mapping
between the image data values and the colors in the CLUT used to
display them. For example, you can transform the data to be
displayed using all the colors, or shift or compress the data to map
it to a particular color or range of colors.
Displaying images in RGB
A computer screen produces colors by illuminating red, green, and
blue phosphors for each pixel. When you change the transform of an
RGB image display, ER Mapper controls mapping between the image
data values and the brightness of the red, green, or blue phosphors
of the hardware display.
The Transform buttons
By default, most raster data layers in ER Mapper have two Transform
buttons in the algorithm process stream diagram. One applies a
transform before a formula (pre-formula), and the other applies a
transform after a formula (post-formula). You can also insert and
append additional transforms in either location to create more
complex contrast enhancements.
Enhancing image contrast
77
pre-formula
transform
post-formula
transform
The Transform dialog box
When you click on one of the Transform buttons in the process
stream diagram or on the Edit Transform Limits toolbar button,
ER Mapper opens the Transform dialog box. This dialog provides
many interactive controls for enhancing contrast and modifying color
mapping.
insert, delete,
or copy transforms
X,Y data values
of current mouse
position
choose X and Y
axis limits options
Y axis (display)
maximum field
click to choose
an automatic
transform option
visual lookup table
for current layer
click to view
transforms in
other layers
click to view
other transforms
in current layer
actual min & max
dataset values
input and output
histograms
transform line
(drag to adjust)
A key concept in using the Transform dialog is moving the
transform line, because this is the feature that controls mapping of
data values to display brightness or color. To move the line, simply
drag it to a new location, or click buttons that automatically position
the line for common transform techniques (such as histogram
equalization).
78
Enhancing image contrast
For any algorithm, you can open the Transform dialog box from
two places: using the Transform buttons in the process stream
diagram on the Algorithm window, or using the Edit
Transform Limits toolbar button. (Using the toolbar button lets
you edit the transforms for any algorithm layers without having
to open the Algorithm window first.)
Hands-on
exercises
These exercises introduce you to the basic features of the
Transform dialog box, and how to use them to enhance image
contrast and color mapping.
What you will learn... After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
Before you begin...
•
Edit the transform for a particular raster data layer.
•
Apply linear and piecewise linear transforms.
•
Edit the input (data) and output (display) ranges for a transform.
•
Use the automatic transform options.
•
Work with multiple transforms in a layer.
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Viewing image histograms
Objectives
Learn to display the histogram for an image, view data values and display a coordinate
grid over the histogram.
Load and display an
image in grayscale
1. On the Standard toolbar, click on the Edit Algorithm
button.
An image window and the Algorithm dialog box appear.
2. In the process stream diagram on the Algorithm window, click on
the Load Dataset
button.
The Raster Dataset file chooser dialog opens.
3. From the Directories menu, select the path ending with the text
\examples.
2
Enhancing image contrast
Double-click on the directory named Shared_Data.
79
4. Double-click on the image named SPOT_Pan.ers.
ER Mapper loads the SPOT Pan image into the Pseudocolor layer and
displays it.
5. On the Surface Tab, from the Color Table drop-down list, select
grayscale.
ER Mapper redisplays the image in grayscale. This is a SPOT
Panchromatic satellite image of the San Diego, California area. (The
image is initially somewhat dark, and you will improve the contrast
later.)
View the histogram for
the SPOT Pan image
1. Click on the post-formula Edit Transform Limits
button in the
process stream diagram.
The Transform dialog box opens. The histogram for the SPOT Pan
image is displayed in the histogram window portion of the dialog.
A histogram is graphical display of the relative frequency distribution
of values in an image. In this case, most of the data values occur in
the lower part of the 0 to 255 data range possible for SPOT Pan
images. Peaks in the histogram show where there are many pixels
with similar data values and often indicate identifiable features in an
image.
View the data values
inside the histogram
window
1. Point the mouse to any location inside the histogram window.
The X and Y axis data values at that point are displayed in the upperleft portion of the dialog (below Histogram Style). The X location
(image data range) appears on the left, and the Y location (screen
brightness or LUT value) is on the right.
2. Position the pointer in the lower-right portion of the histogram
window.
You see a high X value because you are at the upper end of the data
range, and a low Y value because you are at the lower end of the
display or lookup table range.
3. Position the pointer in the upper-left portion of the histogram
window.
You see a low X value because you are at the lower end of the data
range, and high Y value because you are at the upper end of the
display or LUT range.
Turn on a coordinate grid
1. Turn on the Grid option button.
80
Enhancing image contrast
A grid appears over the histogram window with a regular spacing
between grid lines and the origin in the lower-left corner. This grid
can help you quickly determine a specific X-Y data location in the
histogram window.
2. Turn the Grid option off again.
The grid disappears from the histogram window.
Close the Transform
dialog and the Algorithm
window
1. Click Close on the Transform dialog to close it, then click Close on
the Algorithm window to close it.
2: Using linear
transforms
Objectives
Learn to use simple linear transform adjustments to perform lightening and darkening
of images, and increase or decrease image contrast. You also learn to open the
Transform dialog from the Common Functions toolbar.
Reopen the Transform
dialog from the toolbar
1. On the ER Mapper main menu, click the Edit Transform Limits
button on the Common Functions toolbar.
ER Mapper opens the Transform dialog box again. (This is a
shortcut to access transforms for any displayed algorithm without
using the Algorithm window.)
Apply a linear lightening
effect to the image
Whenever you display data in a Pseudocolor layer, the colors in the
lookup table (grayscale in this case) are shown in a color bar along
the Y axis. This makes it easy to see how the position of the
transform line affects the way LUT colors are used to display the
image.
2. As shown in the diagram below, drag the circled part of the transform
line up to the left along the left-hand vertical axis.
Enhancing image contrast
81
ER Mapper applies the change and the image lightens. As shown in
the right-hand diagram, you have adjusted the transform line to
exclude values of about 0-100 on the display (vertical) axis, which
correspond to the darker shades of gray in the grayscale lookup
table. Now the entire 0-255 range of data on the X (horizontal) axis
is mapped to only the lighter shades of gray in the grayscale lookup
table, causing the image to appear lighter.
Also notice that a second unfilled histogram appears in the window.
This is the output histogram, and it represents how your change
affected the distribution of data on the display (or output) axis.
3. Click on the Create default linear transform
button.
ER Mapper returns the transform line to its default position and
redisplays the image. (The default position is a straight linear
transform, where the line’s X position is equal to its Y position. This
also makes the output histogram the same as the input histogram,
so it is no longer visible.)
Apply a linear darkening
effect to the image
1. As shown in the diagram below, drag the circled part of the transform
line up to the right along the right-hand vertical axis.
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Enhancing image contrast
ER Mapper applies the change and the image darkens. As shown in
the right-hand diagram, you have adjusted the transform line to
exclude values of about 200-255 on the display (vertical) axis, which
correspond to the lighter shades of gray in the lookup table. Now the
entire 0-255 range of data on the X (horizontal) axis is mapped to
only the darker shades of gray, causing the image to appear darker.
Also notice that the linear darkening effect caused the output
histogram to shift left of the input histogram (whereas the lightening
effect it shifted it right).
2. Click on the Create default linear transform
button.
The transform line returns to its default position and the image
redisplays.
Apply a linear contrast
stretch to increase image
contrast
1. Point to the far right-hand edge of the histogram (at the bottom of
the slope).
Note that X value displayed in the upper-left shows about 160-170.
Even though the upper limits of the image values are close to 255,
there are very few values between about 170 and 255 (as indicated
by the frequency shown in the histogram).
2. As shown in the following diagram, drag the circled part of the
transform line up to the left along the horizontal axis.
Enhancing image contrast
83
ER Mapper applies the change and the image contrast increases.
Now the contrast between light and dark parts of the image is
enhanced, making spatial features easier to visually interpret. In this
case, you adjusted the transform line to map data values of about
170-255 on the horizontal axis to the lightest color in the lookup
table (white), and spread the remaining data values (0-169) over the
entire range of gray shades.
This mapping better utilizes the dynamic range of gray shades in the
lookup table, which improves image contrast. (This effect is often
called histogram clipping because it clips the tail off the histogram.)
3. Click the Create default linear transform
button.
ER Mapper returns the default transform line and redisplays the
image.
3: Highlighting
features
Objectives
Learn to use piecewise linear transforms to create more complex contrast adjustments
that highlight a specific range of values or a feature in an image.
In contrast to the simple transform adjustments you used earlier,
piecewise linear transforms break the transform line into several
parts (or “pieces”). Each piece of the line can have a different slope
(X-Y relationship), which lets you modify the mapping of that range
of data differently from other pieces of the line. Piecewise linear
transforms lets you create more complex types of contrast
enhancements.
84
Enhancing image contrast
Adjust the transform to
maximize contrast in the
ocean areas
The image you are working with is a SPOT Panchromatic satellite
image, which records the amount of light reflected from the earth’s
surface (similar to an aerial photograph). Notice that the image
histogram has two peaks that provide information about features in
the image:
•
One very tall, narrow peak on the left–these are primarily the
ocean areas in the image. Ocean areas typically have low
reflectance values that fall within a very narrow range (since the
sea surface has little variation compared to the land).
•
Another smaller, wider peak to the right–these are primarily the
land areas in the image. Land areas typically have higher
reflectance values than ocean, and the values are spread out
over a much wider range (since land areas are comprised of a
variety of different cover types).
4. As shown in the diagram below, drag the transform line in two
different places–once down the left edge of the ocean peak in the
histogram, and another up to the top in line with the right edge of
the ocean peak
The contrast in the ocean areas is enhanced, while most land areas
are displayed as white. In this case, you adjusted the transform line
to map the narrow range of data values 30-45 (ocean) over the
entire range of gray shades in the lookup table. Data values lower
than 30 are mapped to the lowest slot in the lookup table (black) and
data values over 45 (mostly land) are mapped to the highest slot
(white). The subtle reflectance patterns in the ocean areas are now
easier to visually interpret because the entire gray shade range is
used to represent them.
5. Click on the Create default linear transform
Enhancing image contrast
button.
85
Adjust the transform to
maximize contrast in the
land areas
1. As shown in the diagram below, drag the transform line in two
different places–once down the left edge of the land peak in the
histogram, and another up to the top in line with the right edge of
the land peak.
The contrast in the land areas (data values between about 45 and
160) is enhanced, while the ocean areas (30-45) are displayed as
pure black.
2. Click on the Create default linear transform
button.
4: Modifying data
and display
ranges
Objectives
Learn to use the Limits menu options to specify exact ranges of data values and
display values to modify image contrast and color mapping.
Use Limits to Actual to set
the X axis data range
Look at the “Actual Input Limits” field on the Transform dialog, and
note that it shows values between approximately 22 and 254.
ER Mapper records the actual range of data values it finds in the
image and displays the results in the Actual Input Limits field.
1. From the Limits menu, select Limits to Actual.
The data range displayed on the horizontal axis changes to match
the Actual Input Limits field.
ER Mapper recomputes the histogram and applies the transform only
to the actual range of data in the image.
86
Enhancing image contrast
Note that the image actually darkens slightly. Since there was no
data between zero and 24, Limits to Actual shifted the entire
histogram slightly to the left on the X axis, so the data is mapped to
slightly darker shades of gray on the lookup table.
Limits to Actual is a very commonly used option because it
allows you to work with only the actual range of data in an
image. This is especially useful for images that do not use an 8bit (0-254) data range. Limits to Actual is very often the first
step in adjusting contrast, followed by another adjustment such
as one of the automatic transform options discussed later.
Set the input limits to
99% of the histogram
range
1. From the Limits menu, select Input Limits to 99% Histogram.
The data range on the horizontal axis changes to approximately 34
to 151, and the histogram itself widens to fill the X axis range.
Input Limits to 99% Histogram clips off 1% of all data values in
the image, taking 0.5% from the lower end, and 0.5% from the
upper end. (The results of the clipping indicates that only 1% of the
image data values fall in the ranges 24-34 and 151-254.)
The image lightens quite a bit since only the range of data where the
most values occur is being mapped to the gray shades. (The 0.5%
of data values at the upper and lower ends are mapped to white and
black respectively.)
Input Limits to 99% Histogram works from the range of data
displayed in the current histogram, which can be different than
the actual image limits if you have entered your own axis limits
(as discussed later).
Set exact input limits to
highlight the ocean data
range
The two text boxes below the histogram window let you type in new
values to define the lower and upper X axis limits.
2. Inside the histogram window, point to the right side of the tall,
narrow peak in the histogram.
As mentioned previously, this peak corresponds primarily to the
ocean portions of the satellite scene. Note that the X value is about
50, so the ocean peak has a minimum value of about 34 and a
maximum value of about 50.
3. Select the text in the X axis maximum text box (currently about
154), and enter a value of 50.
ER Mapper applies the new X axis limits and renders the image.
Enhancing image contrast
87
Now the ocean areas are mapped to the entire range of gray shades
to highlight subtle features, while the land areas (values greater than
50) are mapped to white. This is another method to map a specific
range of data to the entire display range. (Earlier you adjusted the
transform line to accomplish the same enhancement.)
4. On the Algorithm window, change the Lookup Table to rainbow.
The ocean areas are displayed in many colors, while the land is
displayed mostly in red (the last color in that lookup table).
Set exact output limits to
use specific lookup table
colors
1. From the Limits menu, select Limits to Actual.
The X axis range changes to match the Actual Input Limits field.
ER Mapper recomputes the histogram and applies the transform.
2. Change the Y axis minimum value (currently zero) to 200.
The entire image is displayed in shades of yellow, orange, and red
because those colors occupy the upper slots in the rainbow lookup
table.
The color bar display does not change when the Y axis limits are
changed because it is still desirable to see the entire range of
available colors.
3. Change the Y axis minimum value to 50, and change the Y axis
maximum value to 150.
The entire image is now displayed in shades of cyan and green
because those colors occupy the middle slots in the rainbow lookup
table (slots 50-150).
You can also use the Y axis limits to rescale data. For example,
to rescale the range of a target image dataset to match a source
image dataset, edit the Y axis transform limits for the target
image to match the input limits of the source image. You can
then save as a Virtual Dataset or disk file for further processing.
5: Using
automatic
transform options
Objectives
88
Learn to use the automatic transform options such as autoclipping, Histogram
Equalization, Gaussian Equalization, level slicing, and others.
Enhancing image contrast
The automatic transform buttons are displayed on the right side of
the Transform dialog box. Any time you select one of these options,
ER Mapper automatically updates the image display in real time.
Reset the image display
to grayscale and the
default transform
1. Change the Y axis minimum value back to 0, and change the Y axis
maximum value back to 255.
2. On the Algorithm window, change the Lookup Table to grayscale.
Apply an autoclip
transform to the data
3. On the Transform dialog, click the Create autoclip transform
button.
ER Mapper automatically repositions the transform line, and the
image updates automatically with increased contrast.
Autoclipping clips off the “tails” of the histogram to map the more
frequently occurring data values to the selected display range. By
default, ER Mapper performs a 99% autoclip that clips 0.5% of the
data at the high and low ends of the data range. Outlying data values
on the low end of the data range are assigned zero in the display
range (black in this case), and outliers on the high end are given the
maximum value (usually 255, white in this case). (This is similar to
the Input Limits to 99% Histogram used earlier, but the transform
line is automatically adjusted rather than the data range.)
4. This time, double-click the Create autoclip transform
button.
A dialog box appears to let you enter any autoclip percentage. The
default is 99%.
5. Enter the value 95, then click OK to close the dialog.
The transform line is repositioned closer to vertical to clip the
outlying 5% of the histogram frequency distribution (2.5% of the
data values from the high and low ends). The image displays with
greater contrast between light and dark areas.
For best visual results, keep your autoclip percentages greater
than 90%. Values around 99% are most commonly used, but
lower percentages are sometimes a good alternative for
enhancing images with many outlying values.
6. Double-click the Create autoclip transform
button again,
enter the value 99, then click OK.
A 99% autoclip transform is again applied an the image is updated.
Enhancing image contrast
89
The 99% Contrast enhancement
toolbar button is a fast
way to perform all these operations with one click, so it is
especially useful for contrast stretching images that produce
narrow or negative data ranges (such as ratios, PCs, and
others).
Apply a Histogram
equalize transform to the
data
1. On the Transform dialog, click the Histogram equalize
button.
ER Mapper creates a complex piecewise linear transform line and
updates the image.
Histogram equalization (also called uniform distribution stretching)
automatically adjusts the transform line so that image values are
assigned to display levels based on their frequency of occurrence.
More display values are assigned to the most frequently occurring
portion of the histogram, so the greatest contrast enhancement
occurs in the data range with the most values (peaks in the
histogram). Histogram equalization usually creates an image with
very strong contrast between dark and light areas. In some cases, it
can also saturate light and dark areas which can obscure detail.
Apply a Gaussian equalize
transform to the data
1. On the Transform dialog, click the Gaussian equalize button.
ER Mapper creates a complex piecewise linear transform line
(sometimes with slight stair steps) and updates the image.
Gaussian equalization automatically adjusts the transform line so
that image values are assigned as needed to make the output
(display) values occur with a Gaussian distribution. (A Gaussian, or
“normal” distribution, is characterized as producing a bell-shaped
histogram. Notice that the output histogram has a shape close to
this.)
Gaussian equalization is useful when data is skewed in such a way
that features could be abnormally dark or light if stretched linearly.
This technique prevents saturation of light or dark areas, and most
pixels have mid-range brightness values with only a few in the
extreme dark or light display regions.
You can set the number of standard deviations used for the
Gaussian equalize function by double-clicking on the button.
Smaller values produce more contrast and higher values less
contrast. The default is 3 standard deviations.
90
Enhancing image contrast
Apply a level slice
transform to the data
Level slicing (or density slicing) divides the image into discrete colors
and removes transitional colors between them. The resulting images
appears to be divided into “slices,” each displayed in a specific color.
This technique can be useful for looking at data in discrete intervals
and colors.
1. On the Transform dialog, click the Create level-slice transform
button.
ER Mapper creates a stair-stepped transform line at regular
intervals.
2. Double-click the Create level-slice transform
button.
A dialog box appears to let you enter a number of steps for the
transform line.
3. Enter the value 3, then click OK to close the dialog.
The transform line is divided into three steps and the image is
updated.
The stair-stepped transform divides the image into three shades–
black for mostly ocean areas, mid-gray for middle reflectance land
areas (such as vegetation), and white for high reflectance land areas
(such as roads, sand, and airport runways).
Apply a Logarithmic and
Exponential transforms
to the data
1. On the Transform dialog, click the Create default logarithmic
transform
button.
The transform line changes to a smooth curve pointing toward the
upper-left corner of the histogram window, and the image becomes
very light.
2. Drag the transform down line by its mid-point to flatten it slightly.
The line retains its smooth curve, and image becomes darker.
3. On the Transform dialog, click the Create default exponential
transform
button.
The transform line changes to a smooth curve pointing toward the
lower-right corner of the histogram window, and the image becomes
very dark.
4. Drag the transform up line by its mid-point to flatten it slightly.
The line retains its smooth curve, and image becomes lighter.
Enhancing image contrast
91
The Logarithmic transform type is useful for specialized
enhancement purposes, such as displaying data with a large
dynamic range, or to reduce apparent darkness in an image
while retaining the variation in brightness. The Exponential
transform is useful for processing geophysical data with a small
dynamic range to increase the contrast in the displayed image.
6: Working with
multiple
transforms
Objectives
Learn to insert, append, and delete transforms from the processing stream, and use
multiple transforms.
Open the Algorithm
window
1. Click the Edit Algorithm
toolbar button.
ER Mapper opens the Algorithm window. You can now view the
process stream diagram (which is needed for this exercise).
Apply a 99% autoclip
transform to the data
1. Click the 99% Contrast enhancement
button.
ER Mapper applies a 99% autoclip transform to the image.
Insert a second
transform before the
current one
1. From the Edit menu on the Transform dialog, select Insert new
transform.
A second transform (and button) is added to the process stream
diagram on the Algorithm window (it is inserted before the previous
one). Its contents, currently empty, are shown in the Transform
dialog.
Delete the new transform
from the process stream
1. From the Edit menu on the Transform dialog, select Delete this
transform.
The current transform (the new one you inserted) is deleted from the
process stream diagram.
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Enhancing image contrast
Append a second
transform after the
current one
1. From the Edit menu, select Append new transform.
A second transform (and button) is added to the process stream
diagram (it is appended after the previous one).
The histogram shows the data range (0-255) after it has been
passed through the 99% autoclip transform preceding it.
Specify Gaussian
equalization for the new
transform
1. On the Transform dialog, click the Gaussian equalize
button.
ER Mapper creates a Gaussian equalization transform line and
updates the image. The resulting image is created by applying two
transforms–a 99% autoclip followed by a Gaussian equalization of
the autoclipped result. This is an example of enhancing an image by
combining the characteristics of two different types of transforms.
Move to the previous
transform and histogram
1. On the Transform dialog, click the Move to previous transform
in layer
button.
The contents of the Transform dialog box change to show the
previous transform in the process stream diagram (the one applying
a 99% autoclip). Also note that the corresponding transform button
in the process stream diagram is now depressed.
Note that the Y axis limits are zero to 255. The transform rescales
the original data range (22-254) into the 0-255 range. The rescaled
range is used as the input data range for the transform following it.
2. Click the Move to next transform in layer
button.
The contents of the Transform dialog change to show the next
transform (the one applying a Gaussian equalization).
Note that the Actual Input Limits are zero to 255. These were created
by setting 0 and 255 as the output (Y axis) data range for the
previous transform.
Depending on the types of raster layers in your algorithm, the
Transform dialog may display other buttons that allow you to
move between transforms in those layers (such as red, green,
and blue).
Enhancing image contrast
93
3. Click Close on the Transform dialog to close it.
7: Using
automatic
contrast
stretching
Objectives
Learn to use the button that automatically enhances image contrast. This lets you
quickly view various image band combinations without needing to manually set actual
limits each time.
Open an RGB algorithm
1. On the main menu, click the Open
toolbar button.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the Data_Types directory to open it.
4. In the Landsat_TM directory, open the algorithm RGB_741.alg.
ER Mapper displays bands 7, 4 and 1 of a Landsat TM image of the
San Diego, California area.
Change the band
combination to RGB=321
1. Using the Band Selection drop-down menu (in the Algorithm
window), change the image band in the Red layer to B3:0.66_um.
2. Change the image band in the Green layer to B2:0.56_um.
•
ER Mapper reprocesses the RGB algorithm with the new bands.
•
Notice that the image displays in reddish hues (this band
combination usually creates a brown-green image when contrast
stretched appropriately). This is caused by the current
transforms for the Red and Green layers still being set to the data
limits for the previous bands (7 and 4) rather than the new bands
you selected (3 and 2).
Use the Refresh Image
button to enhance the
contrast
1. On the main menu, click the 99% Contrast Enhancement
button.
ER Mapper performs some internal operations, then re-runs the
algorithm to display the image with an appropriate contrast stretch.
94
Enhancing image contrast
The 99% Contrast Enhancement
button is actually a batch
script that performs the following sequence of operations for you:
runs the algorithm once to determine the actual limits of each band,
sets the input (X) axis limits to the actual data limits, runs the
algorithm again to generate the new histogram, applies a 99%
autoclip transform, then runs the algorithm once more to the display
the image onscreen.
The 99% Contrast Enhancement
button saves you the
contrast enhancement steps of setting each layer to Limits to
Actual and applying an autoclip transform. Therefore it is very
useful for initially viewing new images, and when using formulas
or filters that produce data ranges outside 0-255. View different
image band combinations
2. Select B4:0.83_um for the Red layer, B3:0.66_um for the Green
layer, and B2:0.56_um for the Blue layer.
3. Click the 99% Contrast Enhancement
button to
automatically adjust the contrast and display the new band
combination.
A contrast enhanced image of an RGB=432 band combination
displays. Vegetation is shown in red, and urban areas in cyan and
gray.
4. Select B5:1.65_um for the Red layer, and B4:0.83_um for the
Green layer.
5. Click the 99% Contrast Enhancement
button.
A contrast enhanced image of an RGB=542 band combination
displays. Vegetation is shown in green, and urban areas in magenta.
View a different image
and bands
1. In the process stream diagram, click the Load Dataset
button.
The Raster Dataset file chooser dialog box opens.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the Data_Types directory to open it.
4. In the Ers1 directory, double-click on the image Landsat_TM.ers
to load it into all three layers.
Enhancing image contrast
95
5. In the process stream diagram, click the post-formula Edit
Transform Limits
button for the Red layer. The histogram and
transform from the previous image is still displayed.
6. Click the 99% Contrast Enhancement
button and watch the
transform dialog as ER Mapper automatically adjusts it.
The transform is automatically adjusted to account for the new
image limits and the RGB=542 band combination is displayed. This
image is a Landsat TM image of the Netherlands coastal area in
Europe.
To speed this operation, ER Mapper internally runs the algorithm
at low resolution, then processes the final screen image at full
resolution. Therefore the input (X) axis limits in the Transform
dialog (calculated at low resolution) may not exactly match the
Actual Input Limits field (calculated from the final processing).
You can manually reset the limits at this point to fine tune the
contrast, but usually this is not needed.
7. Try various band combinations such as RGB=741, RGB=321, and
others, then click 99% Contrast Enhancement
to display the
new composite image.
Close all image windows
and dialog boxes
1. Close all image windows using the window system controls:
•
Select Close from the window control-menu.
2. Click Close on the Algorithm window to close it.
Only the ER Mapper main menu should be open on the screen.
What you learned
96
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Edit the transform for a particular raster data layer.
•
Apply linear and piecewise linear transforms.
•
Edit the input (data) and output (display) ranges for a transform.
•
Use the automatic transform options.
•
Work with multiple transforms.
Enhancing image contrast
A quick example
Sunshading and
colordraping
This chapter gives an example of how you can quickly and easily
process and display your image data using supplied wizards and
algorithms to help you find specific features that you are looking for.
A unique feature of ER Mapper is the ability to display the same
dataset in different ways to aid interpretation. Here we will create
colordraped and 3D perspective views of some sample magnetics
data.
You can display magnetic datasets and apply sun angle shading to
create relief effects that highlight subtle trends and geological
structures.
A typical example would be to use sun shading to highlight geological
structures and integrate this information with radiometric data using
colordrape to see how the radiometrics correlate with the structures
shown by the magnetic data.
Hands-on
exercises
These exercises show you how to use a supplied wizard and
algorithm to view a magnetics dataset in 3D and colordraped. You
will also learn how to integrate two different (radiometrics over
magnetics) datasets to view them together.
What you will learn... After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
Before you begin...
•
Use a supplied wizard to quickly view an image in
3D and colordraped.
•
Apply real-time sunshading.
•
Colordrape one dataset over another.
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Viewing
sunshaded
magnetics data
Objectives
A quick example
Learn how display images in 3D and colordraped and apply real-time sunshading.
97
Open a magnetics image
and view it colordraped
and in 3D
1. Add the Geophysics toolbar by selecting it from the Toolbars
menu.
2. From the Geophysics toolbar, click on the Common Geophysical
Images Wizard
button.
3. Choose the images you wish to view. In this example, choose
Colordrape and 3D perspective.
4. For the input image, select, from your ER Mapper installation area,
the example\Shared_Data directory and the
Newcastle_Magnetics.ers dataset.
5. Click Finish.
You will get a pop-up message asking you to specify a non-gray
lookup tale for use with the color draped image.
6. Click OK
7. On the Image Properties page click in the Color lookup table to
use: field and select pseudocolor.
8. Click Finish.
ER Mapper will open two image windows, one with the colordraped
image and the other with the 3D perspective view of the Newcastle
Magnetics dataset. You can move around in the 3D window using
combinations of left and right mouse clicks to change the perspective
(tilt, rotate, zoom in and out).
98
A quick example
Apply sunshading to your
image
1. Click on the Colordraped window to make it active, then click on the
Edit Realtime Sun Shade
button to open the Edit Sun Angle
dialog.
A quick example
99
The small circle in the top right quadrant of the concentric circles
represents the position of the simulated sun. Move the sun by
clicking and dragging it with your cursor and see how it highlights
different features as its position changes..
click to turn
shading on/off
type in values
or click arrows
to increment
drag icon to
change sun
azimuth and
elevation
diagram showing
sun position
relative to horizon
(outer circle) or
overhead (center)
2: Colordraping
radiometrics over
the magnetics
data
1. Click the Open
button
2. From the Open window, select the examples directory and choose
the applications\Mineral_Exploration subdirectory and the file
Radiometrics_K_Th_U_RGB_over_Magnetics_RTS.alg.
This image shows radiometrics data in RGB draped over the
structure of the magnetics dataset.
3. Right-click on the image and from the Quick Zoom menu select
Zoom to All Datasets.
4. Turn on the Do sun-shading option.
5. Also notice that the Edit Realtime Sunshade icon in the process
diagram is now a yellow sun
to indicate that shading is active
for the Intensity layer.
100
A quick example
Now the gradients and trends in the magnetics dataset are clearly
defined due to the sun angle shading. This feature allows you to
apply artificial illumination from any direction to highlight very subtle
trends and features.
6. Make the image window larger by dragging lower-right corner of the
window border.
7. Right-click on the image and select Zoom to All Datasets from the
Quick Zoom menu.
ER Mapper redisplays the image to show more detail.
8. Click on the Edit Algorithm
button to open the Algorithm dialog.
It will show Potassium, Thorium and Uranium as RGB layers and Mag
Structure as the magnetics layer.
9. Right-click on the Mag Structure layer and select Turn Off to view
only the radiometric data in RGB.
A quick example
101
102
A quick example
Mosaicing, balancing and compression
This chapter explains how to create algorithms to display and
process two or more separate image datasets as a mosaic. You will
learn how ER Mapper approaches the concept of mosaicing and how
to build an image mosaic algorithm.
The exercises in this chapter show you how to mosaic and balance
images manually and by using the Image Display and Mosaic Wizard
and the Image Balancing Wizard for Airphotos, which simplify image
mosaicing to a large extent. The manual exercises are included to
give you background knowledge and can be skipped over.
About creating
mosaics
In the context of remote sensing, a mosaic is an assemblage of two
or more adjacent or overlapping images to create a continuous
representation of the area covered by the images. You might, for
example, create a mosaic of several overlapping satellite scenes or
aerial photos to cover a larger geographic area. The process of
creating image mosaics is very simple in ER Mapper. Reprojection
on-the-fly allows you to mosaic data from different coordinate
systems using the Image Display and Mosaic Wizard. Any number of
co-registered images used in the same processing algorithm are
automatically displayed in their correct geographic positions relative
to each other.
ER Mapper mosaic
capabilities
You can create mosaics that contain very different types of data. An
image mosaic can be built with datasets that have:
Image display priority
•
different numbers of bands (i.e., seven for Landsat TM versus
three for SPOT XS)
•
different data formats (i.e., byte format versus floating point
format)
•
different resolutions or cell sizes (i.e., 30 meter versus 10
meter).
•
different coordinate systems (i.e., different datum, projections
and rotations).
By changing the order of the algorithm layers containing the
separate image datasets, you can control dataset display priority
(that is, which images appear on top of others in the event of
overlap). Images loaded into the uppermost layer of any type always
appear on top of any other images in layers below where overlap
occurs between them.
Images loaded into the lowest layer of any type always have the
lowest display priority and will only be visible in areas where there is
no overlap from datasets in layers above them. For example, if you
are mosaicing a high resolution image with one of lower resolution,
you can display the entire extents of the high resolution image by
putting its layers on top in the algorithm layer list.
Mosaicing, balancing and compression
103
Layer priority only applies to raster layers; vector layers always
appear on top of raster layers regardless of their position in the
algorithm layer list.
Hands-on
exercises
These exercises show you how to create grayscale and RGB image
mosaic algorithms, and how to use histogram matching and
feathering to help balance image contrast and blend seam lines
between images.You will also learn how to compress an image.
What you will learn... After completing these exercises, you will know how to perform the following tasks in
ER Mapper:
Before you begin...
•
Create an image mosaic by building an algorithm containing two
or more sets of layers of the same type.
•
Specify different processing for each image in the mosaic.
•
Specify image priority for the mosaic (which images appear on
top of others in the event of overlap).
•
Use histogram matching and feathering to minimize seams in
mosaics.
•
Compress a mosaiced image.
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Creating a
grayscale image
mosaic
Objectives
Learn how display several overlapping images in different Pseudo layers to create an
image mosaic, and learn to specify image priority in areas of overlap.
The sample images used in the following exercise were
previously rectified to the same map projection, so they can be
displayed together in a mosaic.
Select files to display and
mosaic
1. On the Common Functions toolbar, click the Image Display and
Mosaic Wizard
104
button.
Mosaicing, balancing and compression
The Select files to display and mosaic page of the Image Display
and Mosaic Wizard opens
2. Click the Load Image
button.
The Select File dialog opens.
3. From the Directories menu (on the Select File dialog), select the
\examples path.
4. Double_click on the Applications directory to open it.
5. Double_click on the Airphoto directory.
6. Open the 3_Balancing directory.
7. Double-click on the image dataset ADAR_Del_Mar_1.ers to select
it.
This dataset is a high resolution image covering a portion of Del Mar,
California near San Diego. This dataset is a multispectral image
acquired by the ADAR 5000 system mounted on an aircraft. The data
values represent reflectance of light in three different wavelengths
(similar to a multispectral satellite image).
Mosaicing, balancing and compression
105
8. Select the below options on the wizard page.
Display image in 2D
Image will be displayed in a 2D mode.
Display image in 3D
Image will be displayed in a 3D mode.
Manually set display method
Enables you to set how the image is to be
displayed. If you do not select this option, the
wizard will set the display method.
Mosaic all files of this type
The wizard will search for files of the same
type and automatically mosaic them.
Manually set mosaic method
Enables you to set how the images are to be
mosaiced. If you do not select this option, the
wizard will set the mosaicing
Contrast stretch image(s) upon loading Enables you to clip all active layers’ output
transforms to a 99.0% linear transform
9. Click on the Next> button to go to the next wizard page.
Select file types to mosaic
This page allows you to specify the characteristics and location of
image files that the wizard must search for to mosaic with the image
already selected.
10. Select the Manually set mosaic properties option. Do not select the
other options on the page.
106
Mosaicing, balancing and compression
The images to be mosaiced all have the same cell sizes, data types
and number of bands. They are also in the same directory.
11. Click on the Next> button to go to the next wizard page.
Select mosaic properties
This page allows you to specify properties of the mosaiced image.
1. Select the Feather blend mosaic between images options. Do
not select the other two options.
To simplify the exercise, we will not be defining and using stitch
regions.
2. Click on the Next> button to go to the next wizard page.
Select display method
This page allows you to specify how you want the mosaiced image to
be displayed.
1. Select the grayscale display option and Manually select display
method properties.
2. Click on the Next> button to go to the next wizard page.
Select display band
This page allows you to select the image band to display as a
grayscale.
1. Select band B1 from the drop-down menu.
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2. Click on the Next> button to go to the next wizard page.
Mosaic and display the
images
The wizard searches the current directory and mosaics and displays
the following images:
•
ADAR_Del_Mar_1.ers
•
ADAR_Del_Mar_2.ers
•
ADAR_Del_Mar_3.ers
3. For the moment, leave the Image wizard has finished page open.
4. Drag the lower border of the image window downward about 50%.
5. Right-click in the image window, select Quick Zoom, then Zoom to
All Datasets.
ER Mapper zooms out to show the full extents of all three ADAR
images.
Since this image mosaic is taller than it is wide, increasing the
window width would have created a large unfilled area on the right
side. This is an example of shaping the window to best fit a particular
image display.
6. On the main menu, click the Edit Algorithm
button.
The Algorithm dialog box opens.
You now have a algorithm that displays band 1 of each dataset as a
grayscale image mosaic.
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7. If necessary, use the Move Up and Move Down
buttons
to arrange the layers so that they are as shown in the diagram
above.
Turn the center image on
and off
1. Right-click on the middle ‘Pseudo Layer’ and select Turn Off.
Only the top and bottom images display (since the center image is
turned off).
2. Right-click on the middle ‘Pseudo Layer’ and select Turn On.
The center image redisplays in its appropriate geographic position
again. Any images in a mosaic can be displayed or not displayed by
turning their layers on or off.
Zoom in to the
geographic extents of any
image dataset
1. Widen the image window
2. Select the top ‘Pseudo Layer’ (‘ADAR_Del_Mar_1’) in the algorithm.
3. Right-click in the image window, select Quick Zoom, then Zoom to
Current Dataset.
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ER Mapper zooms in to the full extents of the ‘ADAR_Del_Mar_1’
dataset (but also displays part of the lower dataset that occupies the
same extents).
Zoom to Current Dataset lets you instantly zoom in or out to the
extents of any raster image datasets in the currently selected layer,
so it is very useful for mosaic algorithms.
2: Creating an
RGB image mosaic
Objectives
Learn how display several overlapping images in different sets of red, green, and blue
raster layers to create an RGB image mosaic.
We use the Image Display and Mosaic wizard to re-display the
existing grayscale mosaiced image as an RGB image.
The final page of the wizard should still be open from the previous
exercise.
Change the image display
method
1. Select the Back to Change display method button from the still
open Image Wizard has finished wizard page.
2. On the Select display method page, select the Red Green Blue
option.
3. Click on the Next> button to go to the next wizard page.
4. Select RGB 123 as the Red Green Blue display mode type.
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This option allocates band 1 to Red. band 2 to Green and Band 3 to
Blue.
5. Click on the Next> button to mosaic and display the images, and to
go to the final wizard page.
The wizard will now display the mosaiced image in RGB mode.
6. Click on the wizard Finish button to exit the wizard. Do not close the
image window yet.
3: Color balancing
the mosaic
Objectives
Learn how to use the Image Balancing Wizard for Airphotos to color balance mosaiced
images so that they interface seamlessly with one another.
Open the Image
Balancing Wizard for
Airphotos
1. Click on the Image Balancing Wizard for Airphotos
button
on the Common Functions toolbar to open the wizard.
The wizard processes the currently active image window which you
left open after the previous exercise
2. Click on the Next> button to go to the next wizard page.
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Analyze images for
balancing
The wizard requires the images to be analyzed before it can do the
balancing. The analysis information is stored in the image dataset
header files. If the images have not yet been analyzed, the wizard
will now do so.
1. Click on the Next> button for the wizard to analyze the images.
The wizard will calculate the statistics for the three ADAR images and
write the information into their respective header files.
2. Click on the Next> button to go to the next wizard page.
Select how to balance the
images
Original
In addition to color balancing, you also have a number of
options for clipping the image. These are described below:
Remove any color balancing and display the unbalanced images.
The white boxes in the diagram show the extents of the individual
images with their edges removed.
Balanced
Display the balanced images but do not clip edges.
Balanced
Display the balanced images and remove the black or white edges.
with no
black/white It is preferable not to select this option when balancing images that
have very dark water, near the edges of the image. The color
edges
balancing wizard for airphotos may select too much of the image as
dark edges to be removed.
Note: Some images are supplied with their black edges already
removed, in which case it is not necessary to select this option.
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Balanced
with clip
regions
When mosaicing images, compute clip regions to hide the edges
between images.
Clip regions are areas of overlap that are trimmed off to create a
seamless join. The wizard re-computes the clip regions every time
you run it.
By default, the wizard turns feathering ON for when balancing with
clip regions, and OFF in all other cases.
Correct for
water areas
If your image has large areas with low contrast, such as water, they
could be discolored by the balancing process. Select this option to
prevent this happening.
Show clip
Create a vector layer which outlines the clip regions.
regions as a
vector
overlay
3. Select the Balanced with clip regions option.
4. Click on the Next> button for the wizard to balance the images and
go to the Color matching page.
The wizard will balance and clip the image. It will then display it in
the image display window as the temp-balance algorithm.
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Color matching the image
You can choose whether you want the wizard to match the colors to
the whole mosaiced image or to one of the images that are part of
the mosaic. Alternatively you can skip the color matching altogether.
For this exercise we will match the color to the
ADAR_Del_Mar_3.ers image.
1. Select the Match colors to individual file option, and then click on
the Next button.
2. Use the file chooser button to select the image to which the colors
are being matched. In this case we will select
ADAR_Dek_Mar_3.ers.
3. Select 99% Linear Clip option to improve the contrast and click on
the Next button.
Do not select 99% Linear Clip if you are going to compress the
image. You will not be able to reverse it when the image is
decompressed.
The wizard will display the status of the color matching. This can take
some time to finish. It will then display the final balanced and
matched image in temporary algorithm.
4. Click on the Finish button to exit the Image Balancing Wizard for
Airphotos.
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4: Compressing
the mosaic
Objectives
Learn how to use the Image Compression Wizard to compress images that can be read
by ER Mapper, Word, ArcView, MapInfo and other software.
Open the Image
Compression Wizard
1. On the main menu, select Save as Compressed image... from the
File menu (or click on the Image Compression Wizard
button
in the Compression toolbar).
The Compression Wizard page opens.
2. Select ECW as the Output Format (from ECW or JPEG 2000).
3. Select the Use the current algorithm window option.
Use the current algorithm window
The algorithm in the current window will be
saved out to a compressed image file.
Select input image (or mosaic) to
compress
Enable you to select a file or mosaic to be
compressed.
Batch compress multiple images
The wizard will search for files of the same
type in a directory and automatically
compress them to the designated output
folder.
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4. Click the Load Image
button.
The Select File dialog opens.
5. From the Directories menu (on the Select File dialog), select the
\examples path.
6. Double-click on the Miscellaneous directory to open it.
7. Double-click on the Tutorial directory.
8. In the Open: text field, click to place the cursor, then type in a name
for the compressed file. Use your initials at the beginning, followed
by the text ‘Compress_mosaic,’ and separate each word with an
underscore (_). For example, if your initials are “JC,” type in the
name:
JC_Compress_mosaic
Make sure the Files of Type is set to ER Mapper compressed images
(.ecw)
9. Click OK to return to the wizard page.
10. Click in the Compress to: field and select Color (RGB).
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11. Click on the Next> button to go to the next wizard page.
The Select compression ratio wizard page opens.
Select compression ratio
This page allows you to specify the compression ratio you would like
to use to compress the image.
1. Set the target compression ratio by entering the desired ratio in the
Target compression ratio: field. For the purpose of this exercise
we will use 50.
2. Select Let the compressor set the output resolution as the
method.
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3. Click the Compute summary information button to view a
summary.
The Computed summary information will display the size of the
uncompressed (input) image (in this case it is 5MB) and the possible
size of the output image. The size of the input image is calculated by
multiplying the number of cells in a line (row) by the number of cells
in a sample (column) by the number of bands in the image (Cell X *
Cell Y * No. bands).
The computed summary information shows you the number of bands
in your image.
4. Click Finish.
A compression progress bar window shows the estimated time
required to complete the task.
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Once the compression is complete, an ECW Compressor dialog box
is displayed which shows the actual compression ratio achieved, the
size of the output file and the time taken for the compression.
In this case the output file was approximately 291KB, representing
a compression ratio of 17.5:1.
5. Click OK to dismiss the ECW Compressor dialog box.
View the compressed
image
1. Select Open from the File menu
2. Navigate to the \examples\Miscellaneous\tutorial directory where
you saved your compressed file and double-click on the
your_initials_Compress_mosaic.ecw file.
The compressed file will open in the image window.
Close the image window
and Algorithm dialog
1. On the main menu, select Close from the File menu to close the
image window.
Click Close on the Algorithm dialog.
Only the ER Mapper main menu should be open on the screen.
What you learned
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Create an image mosaic using the Image Display and Mosaic
Wizard.
•
Use the Image Balancing Wizard for Airphotos to balance the
mosaiced images.
•
Use the Image Compression Wizard to compress images.
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5: Creating a
grayscale image
mosaic manually
Objectives
The rest of the exercises in this chapter involve using manual
methods for mosaicing images instead of using the wizards. We do
recommend that you use the wizards where possible. These
exercises have been included for background information, and you
can skip over them if you so desire.
Learn how display several overlapping images in different Pseudo layers to create an
image mosaic, and learn to specify image priority in areas of overlap.
The sample images used in the following exercise were
previously rectified to the same map projection, so they can be
displayed together in a mosaic.
Open a new image
window and the
Algorithm dialog
1. On the main menu, click the Edit Algorithm
button.
An image window and the Algorithm dialog box open.
2. Click the Surface tab (in the Algorithm dialog), and select
grayscale from the ‘Color Table’ list.
3. Click the Layer tab again to display the process diagram.
Load a dataset into the
Pseudo layer
1. In the Algorithm dialog, click the Load Dataset
button in the
process diagram.
The Raster Dataset dialog opens–move it below the image window
(so the image window and Algorithm dialogs are visible).
2. From the Directories menu (on the Raster Dataset dialog), select
the \examples path.
3. Double_click on the Applications directory to open it.
4. Double_click on the Airphoto directory.
5. Open the 3_Balancing directory.
6. Click once on the dataset ADAR_Del_Mar_1.ers to select it, then
click the Apply button.
ER Mapper loads the dataset into the Pseudo layer and leaves the
Raster Dataset dialog open (you will use it later load additional
datasets).
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This dataset is a high resolution image covering a portion of Del Mar,
California near San Diego. This dataset is a multispectral image
acquired by the ADAR 5000 system mounted on an aircraft. The data
values represent reflectance of light in three different wavelengths
(similar to a multispectral satellite image). Band 1 of the three band
dataset is displayed by default.
Create a mosaic by
adding a second adjacent
dataset
1. In the Algorithm dialog, click the Duplicate
button.
Duplicate button
A copy of the Pseudo layer is added to the layer list.
2. In the Raster Dataset dialog, click once on the dataset
ADAR_Del_Mar_2.ers to select it, then click the Apply this layer
only button.
ER Mapper loads the dataset into only the selected Pseudo layer and
leaves the Raster Dataset dialog open.
Since the two Pseudo layers initially contained the same dataset,
Apply or OK would have loaded the Del_Mar_2 dataset into
both layers. When duplicating layers, use Apply this layer only
to load into only the selected layer.
A portion of the second image displays below the first one.
Zoom out to view the
extents of both images
1. Right-click in the image window, select Quick Zoom, then Zoom to
All Datasets.
ER Mapper zooms out to show the full extents of both ADAR images.
When building image mosaics, Zoom to All Raster Datasets
lets you zoom out to view the full extents of all images
comprising the mosaic. To zoom to the extents of specific
dataset in a mosaic, select the dataset’s layer then use Zoom to
Current Dataset.
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121
Add a third dataset to the
mosaic
1. In the Algorithm dialog, click the Duplicate
button.
A copy of the second Pseudo layer is added to the layer list.
2. In the Raster Dataset dialog, click once on the dataset
ADAR_Del_Mar_3.ers to select it, then click the OK this layer
only button.
ER Mapper loads the dataset into only the third Pseudo layer and
closes the Raster Dataset dialog.
As shown here, if you plan to load multiple datasets into an
algorithm, it is often easier to leave the Raster Dataset dialog
open until you are finished. This saves the time of opening the
file chooser each time.
3. Drag the lower border of the image window downward about 50% so
the image mosaic fits into the window.
Since this image mosaic is taller than it is wide, increasing the
window’s width would create a large unfilled area on the right side.
This is an example of shaping the window to best fit a particular
image display.
You now have a algorithm that displays band 1 of each dataset as a
grayscale image mosaic
.
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Turn the center image on
and off
1. Right-click on the middle ‘Pseudo Layer’ and select Turn Off.
Only the top and bottom images display (since the center image is
turned off).
2. Right-click on the middle ‘Pseudo Layer’ and select Turn On.
The center image redisplays in its appropriate geographic position
again. Any images in a mosaic can be displayed or not displayed by
turning their layers on or off.
Brighten the center
image to enhance the
seam lines
1. Select the middle ‘Pseudo Layer’ containing the ‘ADAR_Del_Mar_2’
dataset.
2. Click the post-formula Edit Transform Limits
button in the
process diagram.
3. On the Transform dialog, click the Histogram equalize
button.
The center image in the mosaic displays with more contrast between
light and dark areas than the top and bottom images, and the seam
lines become clearly visible. (This is helpful for understanding image
display priority in the next section.)
4. Click Close on the Transform dialog.
Change the display
priority of the center
image
1. Select the middle ‘Pseudo Layer’ (‘ADAR_Del_Mar_2’), then click the
Move Up
button.
The layer containing the ‘ADAR_Del_Mar_2’ dataset moves up, so it
is now the top layer (and has display priority over datasets in layers
below it).
The center image ‘ADAR_Del_Mar_2’ displays on top of the other two
datasets where overlap occurs.
2. Point to the top ‘Pseudo Layer’ (‘ADAR_Del_Mar_2’), and drag it to
the bottom of the layer list.
The layer containing the ‘ADAR_Del_Mar_2’ dataset now has the
lowest display priority.
The center image ‘ADAR_Del_Mar_2’ displays underneath the other
two datasets where overlap occurs.
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123
When displaying two or more images in a mosaic algorithm, the
image in the top layer in the Algorithm dialog appears on top
of the others when the algorithm is processed. The image in the
lowest layer has the lowest priority and will only be visible in
areas where there is no overlap from other datasets in layers
above it. By adjusting to order of layers, you can set which
datasets appear on top of others in areas where they overlap.
Zoom in to the
geographic extents of any
image dataset
1. Select the top ‘Pseudo Layer’ (‘ADAR_Del_Mar_1’) in the algorithm.
2. Right-click in the image window, select Quick Zoom, then Zoom to
Current Dataset.
ER Mapper zooms in to the full extents of the ‘ADAR_Del_Mar_1’
dataset (but also displays part of the lower dataset that occupies the
same extents).
Zoom to Current Dataset lets you instantly zoom in or out to the
extents of any raster image datasets in the currently selected layer,
so it is very useful for mosaic algorithms.
6: Creating an
RGB image mosaic
manually
Objectives
Learn how display several overlapping images in different sets of red, green, and blue
raster layers to create an RGB image mosaic.
When creating a mosaic algorithm in Red Green Blue (RGB) Color
Mode, the order of layers becomes slightly more complex but still
works the same way as the single Pseudo layers you used earlier. In
this case, the RGB layers act together as a set, so you normally want
to keep them grouped together in the layer list in the Algorithm
dialog.
Load the template RGB
algorithm
1. On the main menu, click the Open
button.
2. From the Directories menu, select the \examples path.
3. Open the Miscellaneous directory.
4. Open the Templates directory, then open the Common directory.
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5. Double-click on the algorithm RGB.alg to open it.
This algorithm is a template for displaying datasets in Red Green
Blue (RGB) Color Mode. The existing dataset is an airphoto of San
Diego.
Load an ADAR image into
the RGB layers
1. In the Algorithm dialog, click the Load Dataset
button in the
process diagram.
2. From the Directories menu (on the Raster Dataset dialog), select
the \examples path.
3. Double_click on the Applications directory to open it.
4. Double_click on the Airphoto directory.
5. Open the 3_Balancing directory, then double-click on the dataset
ADAR_Del_Mar_1.ers to load it.
ER Mapper loads the ADAR_Del_Mar_1 dataset into all three
layers. (Since all three initially contained the same airphoto dataset,
double-clicking, OK or Apply loads the new dataset into all three
automatically.) By default, band 1 is loaded into the Red layer, band
2 in the Green, and band 3 in the Blue.
This ADAR dataset is the same image you displayed earlier, but is
now displayed as an RGB false color composite. Dataset band 1 (near
infrared reflectance) is displayed in the red layer, band 2 (red
reflectance) in the green channel, and band 1 (green reflectance) in
blue. Vegetation appears red, buildings appear blue or green, and
barren ground appears white.
Add a second group of
new RGB layers
1. Select the ‘Red Layer’ in the layer list.
2. From the Edit menu (on the Algorithm dialog), select Add Raster
Layer, then Blue.
ER Mapper adds a new Blue layer below the Red layer. (Since no
dataset is loaded, the layer is turned off.)
3. From the Edit menu, select Add Raster Layer, then Green.
4. From the Edit menu, select Add Raster Layer, then Red.
Now you have a second set of RGB layers you can use to add a
second image to your RGB mosaic algorithm.
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125
Load an adjacent ADAR
dataset into the new RGB
layers
1. With new Red (lowest) layer selected, click the Load Dataset
button in the process diagram.
2. From the Directories menu (on the Raster Dataset dialog), select
the \examples\Application\Airphoto path.
3. Open the 3_Balancing directory, then double-click on the dataset
ADAR_Del_Mar_2.ers to load it.
The ADAR_Del_Mar_2 dataset is loaded into all three new RGB
layers. (If a set of RGB layers has no dataset, they are treated the
same as a set that has the same dataset when loading data.)
4. Turn on the new Green and Blue layers by right-clicking them and
selecting Turn On.
When loading a dataset into a new set of RGB layers that do not
already have one, only the selected layer (Red in this case) is turned
on by default. You must turn the other layers on as shown here.
Select bands for the new
Green and Blue layers
All three of the new RGB layers contain band 1 of the dataset since
that band is always chosen by default when loading a new dataset
into an empty layer.
1. Select the Green layer containing the ‘ADAR_Del_Mar_2’ dataset,
then select B2:0.650_um from the Band Selection list in the
process diagram.
2. Click on the Blue layer containing the ‘ADAR_Del_Mar_2’ dataset,
then select B3:0.550_um from the Band Selection list.
You now have two groups of Red, Green, and Blue layers. Each group
contains a different dataset but the same assignments of band
numbers to layer types (i.e., band 1 is loaded into both Red layers,
band 2 in both Green, and so on.)
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3. Right-click in the image window, select Quick Zoom, then Zoom to
All Datasets.
ER Mapper zooms out to display the full extents of both images in the
RGB mosaic. You could continue this process to add additional RGB
layers for other datasets in your color composite mosaic algorithm.
Creating multiple sets of
RGB layers
There are several alternative ways to add additional sets of RGB
layers to an algorithm. Three of these alternatives are:
•
Add a new Blue layer (Edit/Add Raster Layer/Blue), load the
new dataset into it, then duplicate it twice and change the
duplicate layers to Green and Red layers.
•
Ctrl-click three RGB layers containing the same dataset to select
them, click Copy
, then click Paste
. This creates a new
set of RGB layers within the same surface that contain the
original dataset, so you can then load the new one.
•
Use File/Add into Current Surface to add the layers from an
existing RGB algorithm into the selected surface of the current
algorithm.
7: Using
histogram
matching
Objectives
Learn how to use ER Mapper’s histogram matching feature to help balance contrast
between multiple images in a mosaic.
Histogram matching is the process of automatically modifying the
transform lines for one or more datasets to force their output
histograms to match the output histogram of a reference dataset.
This is a standard technique used to balance brightness across a
mosaic of datasets to help minimize seams and make them appear
to be one continuous image.
Look at the RGB mosaic you created in part 2 and notice the color
difference between the two images. This is due to the slightly
different range and distribution of data values in the two datasets.
You will use histogram matching to alter the transforms of the layers
containing the ‘ADAR_Del_Mar_1’ dataset to match the output
histograms of the layers containing the ‘ADAR_Del_Mar_2’ dataset.
Open the Transform
dialog box
1. Select the lowest Red layer in the algorithm (for ‘ADAR_Del_Mar_2’).
2. Click the post-formula Edit Transform Limits
button in the
process diagram.
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127
The histogram for the Red layer of the ‘ADAR_Del_Mar_2’ dataset is
displayed.
If needed, move the Transform dialog so it does not overlap with
the Algorithm dialog or image window.
Histogram match the Red
layers
1. In the Transform dialog, click the Histogram match
button.
A dialog appears explaining the effects of the histogram match
function and asking you to confirm that you want to proceed.
2. Click Yes to proceed with the histogram match operation.
3. Click the Move to next red layer
button on the Transform
dialog.
The next Red layer (for band 1 of ‘ADAR_Del_Mar_1’) is selected and
its histogram is displayed. Notice that it has a complex piecewise
transform line–this was automatically created by ER Mapper to make
the output histogram match the output histogram of the Red layer of
the ‘ADAR_Del_Mar_2’ dataset.
Histogram match the
Green layers
1. In the Algorithm dialog, select the Green layer for
‘ADAR_Del_Mar_2’ dataset (the lower of the two Green layers).
Its histogram appears in the Transform dialog.
2. In the Transform dialog, click the Histogram match
button.
The transform line for the other Green layer is modified to match the
output histogram for the current Green layer. Notice the shape of the
output histogram (same as the input or solid green histogram in this
case since the default linear transform line is used).
3. Click the Move to next green layer
button on the Transform
dialog.
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The Green layer for ‘ADAR_Del_Mar_1’ is selected. Notice the shape
of the output histogram (the outline histogram) approximately
matches the shape of the output histogram in the other Green layer.
This is what histogram matching tries to accomplish.
Histogram match the Blue
layers
1. In the Algorithm dialog, select the Blue layer for ‘ADAR_Del_Mar_2’
dataset (the lower of the two Blue layers).
Its histogram appears in the Transform dialog.
2. In the Transform dialog, click the Histogram match
button.
The transform line for the other Blue layer is modified to make its
output histogram match the output histogram of the current Blue
layer.
3. Click the Move to next blue layer
button on the Transform
dialog.
The histogram for the ‘ADAR_Del_Mar_1’ layer and its modified
transform line are displayed.
The brightness differences between the two datasets are minimized
and they appear much closer in color and contrast. This same
technique can be used to histogram match many different images to
a reference image. In this case, ‘ADAR_Del_Mar_2’ was the
reference image, and the transforms of the ‘ADAR_Del_Mar_1’
layers were histogram matched to it.
4. Click Close on the Transform dialog.
You can apply other contrast stretching options such as autoclipping
or Histogram Equalization to your reference layers first, and then use
histogram matching to modify the other layers to match them. This
is likely to be desirable in most cases. (In this case the default linear
transform was used for the reference layers to simplify explanation.)
Histogram matching affects all layers contained in the same
surface. For example, if you have six sets of RGB layers, the
other five Red layers will be matched to the reference Red layer.
Histogram matching does not affect layers in other surfaces in
an algorithm.
8: Using mosaic
seam feathering
Objectives
Learn how to use ER Mapper’s mosaic feathering feature to help blend areas of overlap
to smooth seam lines between images in a mosaic.
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129
Feathering is the process of blending the data values in areas where
two datasets overlap so they gradually transition (or “feather”) from
one to the other. Feathering can help to reduce the visual effect of
seams between two or more images and helps them appear to be
one continuous image. Feathering is an option on the Algorithm
dialog. It is only available when you have more than one of the same
layer type in your algorithm (which is necessary to create an image
mosaic).
Load the mosaic of four
datasets algorithm
1. On the main menu, click the Open
button.
2. From the Directories menu, select the \examples path.
3. Open the Functions_And_Features directory, then open the
Data_Mosaic directory.
4. Double-click on the algorithm
Interactive_mosaic_of_4_datasets.alg.
This algorithm is a grayscale mosaic of four datasets with different
spatial resolutions–a Landsat TM image, a SPOT XS image, and SPOT
Pan image, and a digitized aerial photograph.
Zoom in on a seam line
between two datasets
1. Click the ZoomBox Tool
button on the main menu.
2. Drag a zoom box in the image to zoom in on the vertical seam
between the Landsat and SPOT XS images in the mosaic (see below).
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You should clearly see the seam line and difference in spatial
resolution between the two images (the SPOT XS image on the left
has higher resolution).
Turn on the mosaic
feathering option
Feathering works by blending, or averaging, the data values
between two images in the zone where they overlap:
3. On the Algorithm dialog, turn on the Feather option.
The seam line between the two images is blended to create a smooth
transition between them. Feathering works by progressively
blending the data values in the two datasets in the area where
overlap occurs. Since the feathering computations occur in a left to
right direction, it works best on vertical seams such as in this case.
The figure above on the left shows the graphic with feathering on and the
above right image shows the image with feathering off.
Feathering can also be effective to hide small misalignments
between features on adjacent images. (However gross
misalignments will create a blurred look, and you should consider
rectifying one or both images again to improve this.)
Mosaicing, balancing and compression
131
Close the image window
and Algorithm dialog
1. On the main menu, select Close from the File menu to close the
image window.
2. Click Close on the Algorithm dialog.
Only the ER Mapper main menu should be open on the screen.
What you learned
132
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
•
Create an image mosaic by building an algorithm containing two
or more sets of layers of the same type.
•
Specify different processing for each image in the mosaic.
•
Specify image priority for the mosaic (which images appear on
top of others in the event of overlap).
•
Use histogram matching and feathering to minimize seams in
mosaics.
Mosaicing, balancing and compression
Composing maps
This chapter explains how to use ER Mapper’s Page Setup and Map
Composition tools to create top quality cartographic image maps.
You will learn about setting up a page size and extents for your map,
how to add map objects such as coordinate grids, scale bars, north
arrows, and considerations for printing to hardcopy devices.
About map
composition
ER Mapper provides a complete set of map composition tools that let
you easily transform images into top quality image maps. Your maps
can include common map objects such as coordinate grids, scale
bars, classification legends, north arrows, and more. You can use the
annotation tools to draw lines, text, shaded polygons, and other
vector objects. Your maps can also include other layers to add vector
data from GIS systems, tabular data, or other external data.
ER Mapper’s map composition also has an open design and is userextendable customizable. You can add your own Postscript map
objects to ER Mapper's map object library, such as company logos or
north arrows, include external files and text, and many other types
of data. You can also modify the default attributes of map objects
and save them under your own unique names for later use.
The following diagram shows the general procedure for creating and
printing a map in ER Mapper:
Composing maps
133
Image
processing
Page
setup
Compose
map
Save
algorithm
Print
map
Hands-on
exercises
Create the desired image using algorithm
processing, and any dynamic link vector
or tabular overlays to be included.
Specify page setup parameters for the
algorithm to define its position on an output
page; margins, background color etc.
Compose the map by dragging and dropping the map
objects, specifying object attributes, and
drawing annotation such as lines and text.
Save the vector map composition file, then save
the algorithm containing the annotation/map
composition layer and raster layers.
Print the map on your printer or plotter, or
save it to an external file format (TIFF, CGM etc.)
These exercises give you practice setting up an algorithm to create
a map, defining Page Setup parameters, and composing the map by
adding map objects and other annotation.
What you will learn... After completing these exercises, you will know how to perform these tasks in
ER Mapper:
134
•
Define Page Setup parameters for an algorithm.
•
Display GIS vector data over a raster backdrop image.
•
Add an Annotation/Map Composition layer to an algorithm.
•
Draw annotation objects (lines, text, polygons, etc.) on your
map.
•
Place map objects (grids, scale bars, etc.) on your map.
Composing maps
•
Before you begin...
Specify color and other attributes for annotation and map
objects.
Before beginning these exercises, make sure all ER Mapper image windows are closed.
Only the ER Mapper main menu should be open on the screen.
1: Setting up the
page
Objectives
Learn to use ER Mapper’s Page Setup options to define the position of an image on an
output page, and specify other options such as scaling parameters and background
color.
ER Mapper provides you with two ways of setting up a page. You can
either use the Page Setup dialog box or the Page Setup Wizard.
Both methods achieve the same results, but the Page Setup Wizard
leads you sequentially through the required parameters. Both
methods are described.
Display a Landsat/SPOT
IHS merge algorithm
1. Click on the Open
toolbar button.
An image window and the Open dialog box appear.
2. From the Directories menu, select the path ending with the text
\examples.
3. Double_click on the Functions_And_Features directory to open it.
4. In the Data_Fusion directory, open the algorithm named
Landsat_TM_and_SPOT_Pan_IHS_merge.alg.
This algorithm displays bands 3, 2 and 1 of a Landsat TM image
merged with a high resolution SPOT Pan image as an RGB “natural
color” composite. The image covers the San Diego, California area.
This is the image you will use as the basis for your map.
ER Mapper performs the IHS (Intensity-Hue-Saturation) merge
technique interactively, so you can easily “fine tune” the image
saturation or intensity in real-time using the post-formula
transforms for those algorithm layers. (This technique is also
known as HSI.)
Open the Page Setup
dialog box
If you would rather use the Page Setup Wizard, go directly to
“Open the Page Setup wizard” section below.
1. From the File menu, select Page Setup....
Composing maps
135
The Page Setup dialog box opens. This dialog provides controls for
you to position your image on an output page, specify map scaling,
background color and more.
The white area shows the size of the output print area in red (the
“page extents”), and the size and position of the image on the page
in blue (the “contents extents”).
Specify how the page or
map can be scaled
The Constraints drop-down list lets you specify how map objects
are scaled relative to the output page. For any map, there are three
constraints that will affect how your map looks.
These are:
•
Page size for your final map
•
Scale of the main imagery in your map
•
Border size between the main imagery in your map and the
edges of the page
It follows that if you wish to specify any two of these, then the third
value will be automatically updated by ER Mapper to ensure it fits.
For example, if you use a 8.5"x11" page size, and have settled on a
1:100,000 image scale, then there can be only one size of borders
that will match these requirements.
So, in ER Mapper's page setup, you specify which of the three
constraints are to be autovaried (that is, calculated automatically) by
ER Mapper. You control the other two constraints.
•
If you know the output page size, and the scale you wish to print,
select Auto Vary:Borders.
•
If you know the scale you wish to print, and the size of the
borders you wish to have, select Auto Vary:Page.
•
If you know the border size you want to have, and the output
page size, select Auto Vary:Scale.
Typically you need to decide which parameters are most important
for your map: a fixed page size, fixed borders, or a fixed map scale.
From the Constraints drop-down list, select Auto Vary:Borders.
This tells ER Mapper that it can automatically change the size of page
margins to accommodate any changes in map scale or page size. You
will use this setting to create a 1:100,000 scale map on a US Letter
size (8.5 x 11 inches) page. (Other Constraints options will
automatically change page size or map scale if other parameters are
changed.)
Snap Shot the current
algorithm extents
1. Click the Snap Shot button.
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Composing maps
ER Mapper updates the values in the Contents Extents fields. For
example if you had zoomed in or out in your algorithm, Snap Shot
updates the contents extents to match the current display extents of
your algorithm.
You should typically use Snap Shot even if you have not
zoomed or panned the image to make sure the page contents
extents match the current extents of the algorithm.
Specify the output page
size
1. From the Size drop-down list, select US Letter.
ER Mapper enters the corresponding values in the Page Width and
Height fields, and updates the new margin sizes.
Also notice that the shape of the page extents (in red) matches the
proportions of a US Letter size page. The contents extents (in blue)
are positioned in the upper-left part of the page by default.
Specify the output map
scale
1. In the Scale - 1: text field, enter the value 100000 then press
Enter or Return to validate.
ER Mapper sets the page contents (the physical size of the image on
the page) to print at 1:100,000 map scale and updates the relative
size of the contents on the US Letter size page proportionally.
Position the contents on
the page
1. Click the Horz Center button.
ER Mapper centers the page contents horizontally on the page.
2. Click the Vert Center button.
ER Mapper centers the page contents vertically on the page. The
image is now set to print in the exact center of the output page.
3. In the Borders area of the dialog, edit the value in Top: field to read
50, then press Enter or Return to validate.
ER Mapper shifts the page contents upward slightly on the page. You
can adjust the Borders values to position your image as desired
when creating your map.
Set the background color
to white
1. Select the text in the Background Color field, type white, and press
Enter or Return to validate.
Composing maps
137
ER Mapper sets the page background color to white (the areas of the
page surrounding the page contents). If you will be printing on a
device that has a white background, it is often helpful to set the
background color to white while you are composing the map to get
a better idea of the final output. (You can use the Set Color button
as well to choose any arbitrary background color.)
Save the algorithm with
the Page Setup
parameters
1. Click OK on the Page Setup dialog to save your settings and close it.
From the File menu, select Save As... to save the algorithm under
your own name.
2. Select ER Mapper Algorithm (.alg) for the Files of Type: field.
From the Directories menu, select the path ending with the text
\examples.
3. Double-click on the directory Miscellaneous to open it.
4. Double-click on the directory Tutorial to open it.
5. In the Save As: text field, type a name using your initials at the
beginning, followed by the text San_Diego_map. Separate each
word with an underscore (_). For example, if your initials are JR,
type in the name:
JR_San_Diego_map
6. Click OK to save the algorithm, which now includes your Page Setup
parameters.
Open the Page Setup
wizard
This is an alternative method of setting up the page. If you have
already set up the page using the Page Setup dialog box, as
described above, you can go directly to “2: Defining annotation
objects” below.
1. From the File menu, select Page Setup Wizard....
2. Select the Algorithm displayed in current image window option
on the wizard ’Introduction’ page, and click on the Next> button.
3. On the ‘Use a template’ page, select Define new values with this
wizard and click on the Next > button.
Set the background color
to white
1. Select the text in the Background Color field, type white.
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Composing maps
ER Mapper sets the page background color to white (the areas of the
page surrounding the page contents). If you will be printing on a
device that has a white background, it is often helpful to set the
background color to white while you are composing the map to get
a better idea of the final output. (You can use the Set Color button
as well to choose any arbitrary background color.)
Set the units to Metric (mm) and click on the Next > button.
Set the contents extents
1. Select Snapshot from current zoom, and click on the Next > button.
ER Mapper updates the contents extents to match the current
display extents of your algorithm.
You should typically use Snapshot even if you have not zoomed
or panned the image to make sure the page contents extents
match the current extents of the algorithm.
Set autovary parameter
The Set autovary parameter wizard page lets you specify how
map objects are scaled relative to the output page.
For any map, there are three constraints that will affect how your
map looks.
These are:
•
Page size for your final map
•
Scale of the main imagery in your map
•
Border size between the main imagery in your map and the
edges of the page
It follows that if you wish to specify any two of these, then the third
value will be automatically updated by ER Mapper to ensure it fits.
For example, if you use a 8.5"x11" page size, and have settled on a
1:100,000 image scale, then there can be only one size of borders
that will match these requirements.
So, in ER Mapper's page setup, you specify which of the three
constraints are to be calculated automatically by ER Mapper. You
control the other two constraints.
Composing maps
•
If you know the scale you wish to print, and the size of the
borders you wish to have, select Set scale and borders (page
size varies).
•
If you know the output page size, and the scale you wish to print,
select Set scale and page size (borders vary).
•
If you know the border size you want to have, and the output
page size, select Set borders and page size (scale varies).
139
Typically you need to decide which parameters are most important
for your map: a fixed page size, fixed borders, or a fixed map scale.
1. Select Set scale and page size (borders vary), and click on the Next
> button.
This tells ER Mapper that it can automatically change the size of page
margins to accommodate any changes in map scale or page size. You
will use this setting to create a 1:100,000 scale map on a US Letter
size (8.5 x 11 inches) page. (Other options will automatically change
page size or map scale if other parameters are changed.)
Specify the output page
size
1. Select Choose from standard portrait sizes, and click on the Next >
button.
2. From the Size drop-down list, select US Letter, and click on the
Next > button.
Position the contents on
the page
1. Select Center Horizontally.
ER Mapper centers the page contents horizontally on the page.
2. Select Center Vertically, and click on the Next > button.
ER Mapper centers the page contents vertically on the page. The
image is now set to print in the exact center of the output page.
Specify the output map
scale
1. Select Type in the scale, and click on the Next > button.
2. In the Scale - 1: text field, enter the value 100000 and click on
the Next > button.
ER Mapper sets the page contents (the physical size of the image on
the page) to print at 1:100,000 map scale and updates the relative
size of the contents on the US Letter size page proportionally.
Add a vector layer to
overlay a road network
file
1. Select Add a vector layer.
2. Click on the Vector File: Load Dataset
button.
The Select File dialog box opens to let you load a vector format file.
3. From the Directories menu, select the path ending with the text
\examples.
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Composing maps
4. Double-click on the Shared_Data directory to open it.
Notice that filenames displayed have .erv file extensions. This
indicates that these files are in ER Mapper vector format (in contrast
with raster files that have an .ers file extension).
5. Scroll to view the file San_Diego_roads.erv then double-click on it
to load it into the vector layer.
ER Mapper adds a new layer labeled Annotation Layer to the
algorithm.
Save the algorithm with
the Page Setup
parameters
1. Select Save algorithm to disk.
2. Click on the Save as: Load Dataset
button.
3. From the Directories menu, select the path ending with the text
\examples.
4. Double-click on the directory Miscellaneous to open it.
5. Double-click on the directory Tutorial to open it.
6. In the Save As: text field, type a name using your initials at the
beginning, followed by the text San_Diego_map. Separate each
word with an underscore (_). For example, if your initials are JR,
type in the name:
JR_San_Diego_map
7. Click OK to save the algorithm, which now includes your Page Setup
parameters.
8. Click on the Finish button to close the Page Setup Wizard.
2: Defining
annotation
objects
Objectives
Learn to use ER Mapper’s Annotation tools to display vector data from GIS systems,
and draw annotation objects such as lines, polygons and text. Also learn to zoom the
image in or out to the page extents or page contents.
Open the Geoposition
dialog box
1. Set the View Mode in the Algorithm dialog to Page Layout.
Composing maps
141
The image window displays the whole page with the image in Page
Layout mode. If you select the Normal View Mode, it only displays
the image.
2. From the View menu, select Geoposition....
The Algorithm Geoposition Extents dialog box opens. Move it to
the lower-right portion of the screen.
3. Select the Zoom tab to display buttons for zooming and panning.
Zoom to the Page Extents
and Page Contents
1. On the Geoposition dialog, click the Page Extents button.
The image zooms out to the proportional extents of the page defined
for the algorithm, and the image (the page contents) appears on a
white background. Notice that there is some empty area on the right
side (the stippled white pattern) because the US Letter page is taller
than it is wide.
2. Expand the image window size to make it about twice as tall and
50% wider (so the shape approximately matches the shape of the
white page extents area).
You will use this display later for placing map objects on the page.
3. On the Geoposition dialog, click the Page Contents button.
The image zooms in to the extents of the page contents (the extents
of the image itself). You will first draw some annotation on the image
in this display mode.
Add a vector layer to
overlay a road network
file
1. Click the Edit Algorithm
toolbar button to open the Algorithm
window.
If you used the Page Setup Wizard to set up the page, as
described above, you have already added the vector layer.
Therefore you can go directly to step 7.
2. On the Algorithm window, click on the Edit/Add Vector Layer
button to display its list, then select Annotation/Map
Composition.
ER Mapper adds a new layer labeled Annotation Layer to the
algorithm. Note that this layer has only three buttons in the process
stream since it is designed to display and edit vector data, not
perform image processing on raster images.
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Composing maps
3. In the Algorithm window, click on the Load Dataset
button in
it’s process diagram.
The Load Annotation dialog box opens to let you load a vector
format file.
4. From the Directories menu, select the path ending with the text
\examples.
5. Double-click on the Shared_Data directory to open it.
Notice that filenames displayed have .erv file extensions. This
indicates that these files are in ER Mapper vector format (in contrast
with raster files that have an .ers file extension).
6. Scroll to view the file San_Diego_roads.erv then double-click on it
to load it into the vector layer.
7. In the Algorithm window, click the Edit Layer Color
button in
the process diagram of the annotation layer.
Pick a light blue color, then click OK to close the color chooser.
ER Mapper draws the vector file of roads as a blue overlay.
8. Change the layer description of the vector layer from ‘Annotation
Layer’ to ‘Downtown roads’ and press Enter or Return.
This is a simple example of displaying vector data from an external
system in ER Mapper. (This image of roads was imported and
translated into an ER Mapper format vector file using the menu
command Utilities/Import Vector and GIS Formats.) ER Mapper
also has direct links to many common vector GIS formats.
To edit the vectors (roads in this case), you could click on the
Open Annotation editor
button in the layer’s process
diagram. (Use of these tools is described in the next section.)
Add a second vector layer
for map annotation
1. From the Edit menu (on the main menu), select Annotate Vector
Layer....
The Open Map Composition dialog box opens and indicates that
the algorithm already has a vector layer (displaying the roads
image). You could choose to edit this layer, or add a new annotation
layer.
2. In the Open Map Composition dialog, click the New button.
The New Map Composition dialog opens to let you choose which type
of vector annotation you want to create or work with.
Composing maps
143
3. Click the Vector File option under ‘Mode,’ then click OK on the New
Map Composition dialog to close it.
ER Mapper opens the Tools palette dialog box containing your
vector annotation and map composition tools. Also notice that a
second vector layer titled ‘Annotation Layer’ has been added to the
layer list in the Algorithm window. This is the layer you will use to
add your own annotation and map composition items to the image.
4. Click Close on the Algorithm window (you will not need it for the
remainder of this exercise).
Draw two polylines on the
image
1. On the Tools dialog, click on the Polyline
button.
2. Point to a linear feature inside the image (such as a road). Then draw
a line to trace the feature by clicking once at each point, then doubleclicking to end the line.
A blue line appears on your image to highlight the linear feature.
(The default line color of blue comes from the annotation layer
color.) Note that markers appear on the line at each node to indicate
that the line is “selected.”
3. Point to another linear feature inside the image and draw a second
line by clicking once at each point, then double-clicking to end the
line.
A second blue line appears, and it is now selected.
Modify the attributes of
the polylines
1. On the Tools dialog, double-click on the Polyline
button.
The Line Style dialog box opens to let you choose attributes for your
polylines.
2. Click the Set Color button, choose a bright red color, then click OK
to close the Color Chooser dialog.
The line color on your image changes to red.
3. Choose 2.0 from the Width drop-down list to increase the line
width.
4. Click on a dashed line style under Line Pattern to select a line style.
The attributes for your selected polyline change interactively.
5. On the Tools dialog, click on the Select/Edit Points Mode
button, then click on the first (blue) polyline on the image to select it.
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Composing maps
Notice that the contents of the Line Style dialog change to show the
attributes of the currently selected line (a color of blue and so on).
6. Click Close on the Line Style dialog.
7. Draw a third polyline on the image (it is selected when you finish).
8. In the Tools dialog, click the Delete Object
button.
The polyline object disappears from the image. Selecting an object
and clicking Delete Object is how you delete any annotation object.
To create smooth, rounded curves from polylines made of
straight line segments, you can apply a spline function to the line
by turning on the Curved attribute after first drawing it. This is
especially helpful when tracing roads and other smoothly
varying linear features.
Draw a shaded polygon
around the island
1. On the Tools dialog, click on the Polygon
button.
2. Point to the large island in the lower part of the image. Then draw a
polygon around the island by clicking once at each point, then
double-clicking to close the polygon.
The polygon object appears surrounding the island, and it is selected
by default. (If your polygon is not selected, select it now.) Now you
will change its color and specify a shade pattern to fill it.
3. On the Tools dialog, double-click on the Polygon
button.
The Line Style dialog box opens to let your set polygon attributes.
4. Click the Set Color button, choose a bright yellow color, then click
OK to close the Color Chooser dialog.
5. Under Fill Pattern, click on one of the diagonal line fill patterns.
The pattern you choose appears in the Current Fill window on the
dialog. The polygon becomes yellow and is filled with a diagonal
shade pattern.
6. Click Close on the Line Style dialog.
Draw a shaded oval and
move and resize it
1. On the Tools dialog, click on the Oval
Composing maps
button.
145
2. Point anywhere inside the image, drag an oval shape and release.
A shaded yellow oval appears. By default, the oval is selected (blue
handles appear at the four corners that define the oval extents).
3. On the Tools dialog, click the Select and Move/Resize Mode
button.
Select and Move/Resize Mode lets you move and/or resize the
selected object. Notice that the oval’s selection handles change–now
there are eight handles colored yellow.
corner handles - use to resize
the object proportionally
side handles - use to stretch
or compress object
4. Point inside the oval, and drag it to a new location.
By dragging the object (not by a handle), you can move it on the
image.
5. Point to one of the rectangle’s corner handles and drag it to increase
the rectangle size proportionally.
6. Point to one of the rectangle’s side handles and drag it to stretch or
compress the oval.
Draw, modify and
position text strings
1. On the Tools dialog, click the Text Object
button.
The Text Style dialog box opens.
2. Click in the dark area near the lower-left part of the image (ocean).
A small box with four selection handles appears–this is where your
text will appear on the image.
3. In the Text Style dialog, click in the Text field at the bottom to
position the cursor, then type Pacific Ocean. Press Return or Enter
to validate.
The text appears on the image as you type.
4. In the Text Style dialog box, select the following text attributes:
146
•
Size: 14.0
•
Color: choose any bright color
•
Font: Helvetica-Bold
Composing maps
Notice that the text object automatically updates as you change the
attributes.
5. Click in the dark ocean area on the lower-right of the image.
6. In the Text Style dialog, click in the Text field to position the cursor,
then type San Diego Bay. Press Return or Enter to validate.
7. From the Angle (deg) drop-down list, select 315.0.
The “San Diego Bay” text rotates 315 degrees counter-clockwise, so
it now points down toward the lower right.
8. On the Tools dialog, click the Select and Move/Resize Mode
button.
9. Point to the text block, and drag it to an appropriate position inside
the dark bay area on lower-right of the image.
You have now learned to draw and modify simple annotation objects
such as lines, polygons, and text. Next you will add map objects to
your page.
Text drawn as annotation can be set to always print at an exact
point size (the Fixed Text option), or to scale up or down with
the page when it is printed (the Page Relative option).
3: Defining map
objects
Objectives
Learn to use ER Mapper’s Map Composition tools to place and modify map objects such
as scale bars, coordinate grids, north arrows, and others.
Zoom to the Page Extents
to view the entire map
page
1. On the Geoposition dialog, click the Page Extents button.
The image zooms out to the extents of the page defined for the
algorithm, and the annotation objects are redrawn at their
proportional size. You can now add map composition objects to your
page.
2. Click Close on the Algorithm Geoposition Extents dialog to close
it.
3. On the Tools dialog, click on the Map Rectangle
button.
The Map Object Select and Map Object Attributes dialog boxes
open on the right side of the screen.
Composing maps
147
These dialog boxes let you drag and drop map objects onto the page
in your image window, and specify attributes for the objects.
Layout the types and
positions of map objects
Before creating your map, it is a good idea to determine which types
of map objects you want to use, and their relative sizes and positions
on the page. In this exercise, you will create simple map with the
following objects:
You will define these objects on the page in two ways:
•
draw a bounding box and drag-and-drop the object into it; or
•
drag-and-drop the object onto the page and resize the bounding
box afterward
Use the diagram above as a guide for the size and position of
bounding boxes for map objects you are asked to create in the next
sections.
Add a scale bar centered
below the image
1. Point to the area below the image on the page, and drag a short,
wide bounding box centered below it (refer to the previous diagram
for the size and position).
When you release the mouse, the box is selected and handles appear
at the corners. This box will define the extents of your scale bar
object on the page. (The box appears in the color you chose for the
vector layer earlier.)
2. In the Map Object Select dialog, select Scale Bar from the
Category drop-down list.
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Composing maps
A list of icons representing various types of scale bar map objects
appears. The name of the object is shown in the status line at the
bottom of the dialog when you point to it.
3. Point to the icon titled Scale_Bar/Tick, drag it into the bounding
box you defined in the image window, and release.
The scale bar object is “dropped” into the bounding box and it draws
a few seconds later. The extents of your bounding box are now
indicated by the yellow selection handles. The default attributes for
the scale bar appear in the Map Object Attributes dialog box.
4. On the Map Object Attributes dialog, change the following
attributes for your scale bar:
•
Start Scale at Zero: Yes
•
Number of Divisions: 4 (press Enter or Return afterward)
•
Show Scale: No
•
Left Align Scale Bar: No
Notice that the scale bar object automatically updates as you change
the attributes. Turning off the left alignment centers the scale bar
within your box.
Add a compass north
arrow on the lower-right
1. In the Map Object Select dialog, select North Arrow from the
Category drop-down list.
A list of icons representing various types of north arrows appears.
2. Point to the compass north arrow (North_Arrow/Compass), and
drag it to a position just right of your scale bar.
The north arrow object drops onto the page and draws a few seconds
later at a default size. If desired, make the arrow smaller by dragging
the lower-right handle to resize the bounding box.
ER Mapper’s north arrows are “smart” and will always point to
north on a rectified image.
Add a company logo on
the lower-left
1. In the Map Object Select dialog, select Logo from the Category
drop-down list.
A list of icons showing some sample company logos appears.
2. Point to the ER Mapper logo icon, and drag it into a position left of
the scale bar.
Composing maps
149
The logo object drops onto the page.
You can add your own company logos as Postscript files and
access them from the standard Logos category used here.
Add a main title above the
image
1. Drag a bounding box centered at the top of the image window (leave
some space below it, refer to the previous diagram for the size and
position).
2. In the Map Object Select dialog, select Title from the Category
drop-down list.
3. Point to the icon titled Title/Outline, drag it into the bounding box
you defined above the image.
4. On the Map Object Attributes dialog, change the following text
and attributes for your title:
•
Title: San Diego Image Map (press Enter or Return afterward)
•
Font Color: red
The title object automatically updates as you change the attributes.
Define an
Eastings/Northings grid
over the image
1. In the Map Object Select dialog, select Grid from the Category
drop-down list.
2. Point to the Grid/EN icon, drag it onto the image.
The grid map object draws with a default position and attributes on
the page.
3. On the Map Object Attributes dialog, click the Fit Grid button.
ER Mapper resizes and positions the grid to fit exactly to the extents
of the image on the page. (If desired, you could resize and position
it manually.)
4. On the Map Object Attributes dialog, turn on the Fast Preview
option.
Fast Preview tells ER Mapper not to update the object interactively
as you change the attributes. (Since the grid is a complex object, you
will change all the desired attributes first, then refresh the object all
at once to save time.)
5. On the Map Object Attributes dialog, change the following
attributes for your grid (use defaults for all others):
150
Composing maps
•
Grid Style: Full Grid
•
Grid Spacing X: 2,500 meters (2.5 km)
•
Grid Spacing Y: 2,500 meters (2.5 km)
•
Top labels orientation: Horizontal Right
6. On the Map Object Attributes dialog, turn off the Fast Preview
option.
The grid map object is rendered using the attributes you defined.
Adjust the size or position
of any object
If desired, you can easily resize or position any map object by
moving or resizing the bounding box that contains it.
1. In the Tools palette dialog, click the Select and Move/Resize
Mode
button.
2. Click on any map object to select it (the handles will appear), and
drag the bounding box to reposition it or change the size by dragging
a handle.
Save the annotation/map
composition file to disk
1. On the Tools palette dialog, click the Save As
button.
The Map Composition Save As dialog box opens.
2. Select Vector File for the Save As option and click on the File
Chooser
button to open the Save Map Composition File
dialog.
3. From the Directories menu, select the path ending with the text
\examples.
4. Double-click on the directory named ‘Miscellaneous’ to open it.
5. Double-click on the directory named ‘Tutorial’ to open it.
6. In the Save As: text field, enter a name using your initials at the
beginning, followed by the text ‘map_composition.’ Separate each
word with an underscore (_). For example, if your initials are "KG,"
type in the name:
KG_map_composition
7. Click OK to save the annotation file to disk.
The annotation file contains all the objects you defined–the vector
lines, text and polygons you drew on the image, as well as the map
composition objects, their attributes, and position and size on the
page.
Composing maps
151
8. Click Close on the Map Object Attributes, Map Object Select, and
Tools dialogs to close them.
Save the algorithm to
update the changes
1. On the main menu, click the Save toolbar button.
2. When asked to confirm the overwrite, click OK.
Your algorithm can now be printed using the Print
toolbar
button or by selecting Print from the File menu.
It is important to remember to save your algorithm after
defining map objects. Otherwise the annotation file will not be
part of the algorithm when you attempt to print it later.
Additional features of
Map Composition
152
The preceding simple example covered only the basics of using
ER Mapper’s Map Composition, and following are some additional
features. Refer to the chapter on creating maps in the ER Mapper
User Guide for complete information.
•
If you drag an object into a bounding box that already contains
an object, the old object is replaced by the new one. This is an
easy way to try several north arrows, for example.
•
Objects that are dragged and dropped to replace a current object
automatically inherit any common attributes from the previous
object. For example, if you have a red north arrow in a bounding
box and then drag in a scale bar object, the scale bar
automatically inherits the red color (since both objects have the
“Color” attribute in common).
•
You can modify the default attributes of map objects and save
them under your own names (using Save As on the Map Object
Attributes dialog).
•
You can draw other image processing algorithms you’ve created
as map objects on the page (using the Category: Algorithm on
the Map Object Select dialog).
•
You can plot objects from external files like TIFF, EPS, or Targa
(using the Category: Image on the Map Object Select dialog).
•
You can import text directly from ASCII text files and plot it on
your map page (using the Category: Text on the Map Object
Select dialog).
Composing maps
Page Relative and Map
Unit Relative map objects
The vector map objects you defined in this exercise have their
position and size specified relative to the page, rather than to map
units (such as Latitude Longitude). This allows you to create
standard map sheets with objects that remain in a fixed size and
position on the page, regardless of how the page is scaled or the
extents of the images used in the page contents are changed.
You can also specify the position of map objects in geographic
coordinate units. The position of each object is tied to a particular
geographic location and map sheet size.
To specify a map object as map unit relative, turn off the Page
Relative option on the Map Object Attribute dialog box. The page
relative attribute can be assigned either before or after the object is
dragged-and-dropped onto the page. See the online ER Mapper User
Guide for more information.
Printing your map
When you want to print your final map algorithm (using File/Print
or the Print
button), ER Mapper asks for the name of the
algorithm. When the print operation begins, ER Mapper
automatically locates, processes and renders all the images used in
the algorithm into one final print image. In this case, your map
algorithm uses four images–a Landsat raster image, a SPOT raster
image, a vector roads image, and a vector map annotation image
(which you created).
Since the map algorithm is made of several layers (and images), you
can easily change it. For example, to print the image without the
road network overlay, simply turn off that layer in the algorithm,
resave it, and print it.
Close all image windows
and dialog boxes
Close all image windows using the window system controls:
1. Select Close from the window control-menu.
2. Click Close on the Algorithm window to close it.
Only the ER Mapper main menu should be open on the screen.
What you learned...
Composing maps
After completing these exercises, you know how to perform the following tasks in
ER Mapper:
153
Canadian National
Transformation
Version 2 (NTv2)
Grid-based Datum
Shift Support
•
Define Page Setup parameters for an algorithm.
•
Display GIS vector data over a raster backdrop image.
•
Add an Annotation/Map Composition layer to an algorithm.
•
Draw annotation objects (lines, polygons, etc.) on your map.
•
Place map objects (grids, scale bars, etc.) on your map.
•
Specify color an other attributes for annotation and map objects.
ER Mapper now includes support for NTv2 grid-based corrections for
performing Canadian datum changes. Included with ER Mapper are
the required grid-shift data files (supplied by Natural Resources,
Canada). With these files users can transform data from NAD27 to
NAD83 with much greater accuracy than NADCON (North American
Datum Conversion). In order to perform the transformations, ER
Mapper now specifies two new datums, NAD27A74 (1974 Canadian
NTv2 adjustment) and NAD27A76 (1976 Canadian NTv2
adjustment). The NAD27 to NAD83 datum transformation still
utilizes NADCON, so in order for ER Mapper to perform an NTv2
transformation, the ERS header file of the source dataset must be
edited to reflect an NTv2 datum. An example will help explain this.
The following extract is from an ERS header file for a Canadian
dataset:
DatasetHeader Begin
Version= "7.0"
Name = "Canada.ers"
LastUpdated= Tue Feb 08 02:04:21 GMT 2005
DataSetType= ERStorage
DataType= Raster
ByteOrder= LSBFirst
CoordinateSpace Begin
Datum = "NAD27" <------ needs to change
Projection= "GEODETIC"
CoordinateType= LL
Rotation= 0:0:0.0
CoordinateSpace End
If the user wishes to perform a NAD27 to NAD83 datum
transformation using NTv2, the "Datum" field will have to be
changed to "NAD27A74" or "NAD27A76", depending on which datum
date the user wants to transform from. So the resulting extract from
the header file should look like this:
DatasetHeader Begin
Version= "7.0"
Name = "Canada.ers"
LastUpdated= Tue Feb 08 02:04:21 GMT 2005
DataSetType= ERStorage
154
Composing maps
DataType= Raster
ByteOrder= LSBFirst
CoordinateSpace Begin
Datum = "NAD27A74" <------- allows NTv2 shift to
NAD83
Projection= "GEODETIC"
CoordinateType= LL
Rotation= 0:0:0.0
CoordinateSpace End
Now the user should be able to transform the dataset from
NAD27A74 to NAD83 using the NTv2 grid shift datum change.
To simplify migration to using the new transformation in ER Mapper
you can use the Change_DP_Wizard batch script to convert the
datum specified in your ER Mapper header files from NAD27 to
NAD27A74 or NAD27A76 depending on which grid-shift corrections
you want to apply.
For more information on how to use the Change_DP_Wizard please
refer to the section "Change Projection/Datum/Cell Size Wizard" in
the ER Mapper User Guide.
NTv2 Support for other
Regions
NTv2 support also extends to Australian, New Zealand and French
datum shifts. ER Mapper also includes GDT and grid shift data files
for following transformations:
•
Australian Geodetic Datum 1966 to/from Geocentric Datum of
Australia 1994
AGD66NTV <-> GDA94
•
New Zealand Geodetic Datum 1949 to/from New Zealand
Geodetic Datum 2000
NZ49NTV <-> NZGD2000
•
Nouvelle Triangulation Francaise to/from France 1993
NTFNTV <-> RGF93
As mentioned in the previous example on dataset header changes,
existing ERS header files with the "Datum" field specifying "AGD66",
"NZGD49" or "NTF" first need to be edited to reflect the NTv2
equivalents mentioned above in order to perform the required NTv2
transformations.
Modifying Existing
Datums Changes to Use
NTv2
For convenience, it may be more productive for users to modify an
existing datum so that it always uses NTv2. In order to modify
existing datum change entries to use NTv2 grid-shift data you need
to:
1. Copy the appropriate NTv2 data files to your
<ERMapper>\GDT_DATA directory e.g. NTV2_0.GSB (this has
already been done for you).
Composing maps
155
2. Modify the existing entry for the datum transformation to use NTv2
instead of the current method (e.g. change from either Bursa-Wolf
or NADCON). For example, you can modify ER Mapper's NAD27 to
NAD83 datum conversion to use NTv2 instead of NADCON by
changing the following entry in datumcha.dat from:
NAD27>NAD83, NAD27, NAD83, nadcon, PBN - 8/5/92 NADCON
lower 48,???, PUBLIC
to the following:
NAD27>NAD83, NAD27A74, NAD83, ntv2, NTv2,???, PUBLIC
3. Add an entry to the <ERMapper>\GDT_DATA\ntv2.dat file that
specifies the names of the NTv2 grid-shift data files. Following on
from the example, the line to be added should be:
NAD27>NAD83, 1, NTV2_0.GSB, 0.0, 0.0, 1
This entry tells ER Mapper to use the data in the grid-shift file
NTV2_0.GSB to perform the datum change from NAD27 to NAD83
and vice-versa.
Adding New NTv2
Transformations to ER
Mapper
ER Mapper is also fully customizable to support NTv2
transformations of other regions in addition to Canada, Australia,
New Zealand and France. To add NTv2 transformations to ER Mapper
for other regions you need to follow the following steps:
1. First acquire the NTv2 format grid-shift data files (*.gsb) for your
area and copy them to ER Mapper's GDT_DATA directory. For
example, when adding support for the Canadian NTv2 datum shifts,
the grid-shift data files (NTv2_0.GSB and MAY76V20.GSB), obtained
from Natural Resources Canada, were copied into the
<ERMapper>\GDT_DATA directory.
2. Create an index (*.ind) file for each GSB file you add. This is
necessary for ER Mapper to quickly perform the grid-based
transformations. You can do this by using the utility
<ERMapper>\bin\win32\ntv2_conv.exe e.g. When generating and
index file for the NTV2_0.GSB grid data file, the following command
was executed:
ERMapper\bin\win32>.\erm_run ntv2_conv
..\..\GDT_DATA\NTV2_0.GSB
This effectively created the ntv2_0.ind index file that is already in
your ER Mapper GDT_DATA directory.
3. Next, you need to add a new entry to the
<ERMapper>\GDT_DATA\ntv2.dat file to let ER Mapper know
about the new data files. Information about the new transformation
data files was then added to ER Mapper by adding the following
entries to ntv2.dat:
NAD27A74>NAD83, 1, NTV2_0.GSB 0.0,0.0, 1
NAD27A76>NAD83, 1, MAY76V20.GSB, 0.0,0.0, 1
4. The new datums will also need to be defined in datum.dat. So in the
example, entries for NAD27A74 and NAD27A76 need to be added as
follows:
156
Composing maps
NAD27A74 ,NORTH AMERICAN 1927 (Adjusted
1974),CLA66MTR,1 ,MEADE'S RANCH ,39.2240794 ,98.5418072 ,1 ,0.0 ,1 ,1,,R. GORDON 27/2/89 COPIED FROM
NAD27MTR DATUM ,SURVEY,PUBLIC
NAD27A76 ,NORTH AMERICAN 1927 (Adjusted
1976),CLA66MTR,1 ,MEADE'S RANCH ,39.2240794 ,98.5418072 ,1 ,0.0 ,1 ,1,,R. GORDON 27/2/89 COPIED FROM
NAD27MTR DATUM ,SURVEY,PUBLIC
Note that the numerical parameters are simply copied from the
existing NAD27 entry. These new entries simply provide the user
with the option to specify which transformation to use (i.e. NTv2
1974, NTv2 1976 or NADCON) when going from NAD27 to NAD83
and vice versa.
5. Datum change methods for the newly defined datum pairs also need
to be specified in datumcha.dat. According to the current example,
the entries would be:
NAD27A74>NAD83, NAD27A74, NAD83, ntv2, NTv2,???, PUBLIC
NAD27A76>NAD83, NAD27A76, NAD83, ntv2, NTv2,???, PUBLIC
For more information on the role of datumcha.dat in performing
datum changes please refer to the section "GDT_DATA files and their
interpretation" in the ER Mapper User Guide.
For more information on NTv2 and these adjustments please refer to
the Natural Resources Canada web site at
http://www.geod.nrcan.gc.ca/index_e/products_e/software_e/ntv2
_e.html
©1995. Produced under licence from Her Majesty the Queen in
Right of Canada, represented by the Minister of Natural
Resources.
Composing maps
157
158
Composing maps
Quick reference
This section gives a quick overview of some of the features and
functionality of ER Mapper not already covered by the tutorial
exercises. The aim of the section is to point the user to essential
information that will be required to work efficiently with ER Mapper.
For a more detailed coverage of the topics covered here, as well as
for additional topics, please refer to the ER Mapper User Guide and other
manuals.
Topics covered in this section are:
Quick reference
•
ER Mapper menus and toolbars
•
ER Mapper Wizards
•
ER Mapper algorithms, filters and formulae
•
Classification
•
Dynamic Links
•
Fourier processing
•
Geolinking
•
Importing/Exporting raster and vector images
•
Map projections supported by ER Mapper
•
Printing
•
Virtual datasets
•
ER Mapper documentation
159
160
Quick reference
ER Mapper menus and toolbars
Menus
When you start ER Mapper, the main menu appears. The main menu
has two primary components–the menu bar and rows of toolbar
buttons.
bar
rs
The menus from the menu bar let you select commands used to
carry out actions in ER Mapper. To select a command from the menu
bar, click on the name of the menu to open it, then click the desired
command name from the drop-down list.
A brief description of each of these menus is given here:
File
The File menu gives you the options to open, close and save your
image. Use the Save As... command to save your image under a
different name or another file type. You can also access page setup,
Page Setup Wizard and print options from here.
The Open into New Surface... option allows you to add a new
surface to an existing image, and Add into Current Surface...
allows you to add a new dataset to the current surface.
Open from Virtual Dataset... allows you to choose a virtual dataset
from which to open an image.
The Save As Compressed Image... command starts the Compression
Wizard
The File menu also shows a list of recently accessed images.
The Exit option allows you to exit from ER Mapper.
Edit
This menu allows you to select options for map composition and edit
class/region color and names. You can also edit ARC/INFO coverage.
Set ER Mapper preferences using the Preferences... command.
View
The View menu provides options to view your image in Normal,
Page Layout, 3D Perspective and 3D Flythrough modes.
In addition to the view mode, you can use the following commands
to:
Command
Function
Algorithm...
open the Algorithm window.
Quick Zoom
change your zoom and geolink options.
Geoposition...
open the Algorithm Geoposition Extents window.
ER Mapper menus and toolbars
161
Command
Function
Statistics
calculate, view and save statistical information for your image.
Scattergrams...
set up and view scattergram.
Traverse...
set up and view traverse information.
Batch Engine Script Control
open the Batch Engine Script Control dialog to cancel or run
processes.
Cell Values Profile
view cell values profiles.
Cell Coordinate
view cell coordinates.
Toolbars
Use this menu to view or hide various toolbars supplied with
ER Mapper. See the “Toolbars” section of this chapter for a
description of each toolbar.
Process
The Process menu contains the following commands which help you
carry out various image processing tasks:
Command
Function
Raster Cells to Vector Polygons...
convert raster cells to vector polygons.
Polygon<->Region Conversion
convert vector datasets to regions and regions to vector
datasets.
Calculate Statistics...
calculate statistics for the image.
Classification
carry out supervised or unsupervised classification.
Geocoding Wizard...
start the Geocoding Wizard.
Gridding Wizard...
start the Gridding Wizard.
Digitizer
setup or configure a digitizer.
Radar Common
apply common filters or carry out functions.
Radar Filters
apply supplied radar filters.
Fourier Transformations...
apply Forward and Reverse Fourier Transformations.
Utilities
This menu provides ready-made utilities for exporting and importing
data in different formats. A Help menu is provided for each format.
Click on Help to get details of what each utility does, information
about the data format and a note on how to use the utility.
In addition to the Import and Export utilities, the Utilities menu
also has the following commands:
162
Command
Function
Toolbars
create a new toolbar.
Batch Scripts
create or edit a batch script.
ER Mapper menus and toolbars
Command
Function
File Maintenance
view environment variables, and edit and set
environment variables.
Licensing...
start the ER Mapper Licensing Wizard.
User Menu
edit a custom file.
Machine Configuration Report
start the Machine Configuration Report Wizard to view
and report your machine’s configuration.
Slide Show
run a slide show of the different algorithms provided
with ER Mapper.
Windows
Open a new window using the New Window command.
Help
Use this menu to access the online Help manuals provided with
ER Mapper. See Chapter 26, “ER Mapper documentation” for further
details.
You can also view the ER Mapper License Agreement from this menu.
Toolbars
ER Mapper comes supplied with a number of ready-made toolbars
made up of quick-access function buttons. Some buttons simply
provide an easy alternative way for selecting a menu item. Other
buttons carry out complex strings of commands.
When you first start ER Mapper there are two toolbars showing: the
Standard toolbar and the Common Functions toolbar. As their
names suggest these toolbars contain buttons that are generally
useful for using ER Mapper. In addition, there are sixteen other
toolbars to choose from, dedicated to specialist tasks and
applications.
You turn toolbars on and off using the Toolbars menu. When you
quit ER Mapper, it will remember which toolbars you had showing
and display them again next time you use it.
As well as using the toolbars supplied, you can also edit individual
buttons and create new buttons and toolbars.
This chapter describes the functions of the toolbars that are supplied
with ER Mapper. To create and customize toolbars and buttons you
will need to edit the menu and toolbar files. See Part Four Processing and Configuration Files, “Menu and toolbar files (.erm)
and (.bar)” in the online Customizing ER Mapper manual.
Button logic for creating
algorithms
ER Mapper menus and toolbars
Many of the toolbar buttons will setup algorithms for you. They can
be used in a number of ways. You may want to use them to start a
new algorithm of a particular type from scratch, or you may already
have an algorithm for which you want to change the mode or
processing. When the toolbar buttons set up an algorithm they will
attempt to use any images you are already working with. If there are
none, they will ask you to select one or more as required by the
particular option. The logic for all of the options is similar:
163
•
Standard
Finds a window: If there is no current image window it opens
one.
•
Finds one or more images as appropriate: Finds a layer of a type
•
For pseudocolor algorithms, sets the color table.
•
May apply formulae, filters or other processing, depending on
•
Runs the algorithm, often with a 99% clip on the final output
transform on each layer.
appropriate to the color mode of the algorithm you are creating:
If the mode is correct and an active (on) layer of an appropriate
type is found it processes the image. Otherwise, the algorithm is
searched for an inactive layer of an appropriate type with an
image. If one is found it is turned on. The Color mode is changed
if necessary. If there are no layers of the appropriate type,
ER Mapper looks for any other raster layer with an image and
uses the image from the first layer it finds in new layers
appropriate to the Color mode. If no valid image is found, a file
requester is opened to obtain an image from the user. This image
is then used to generate one or more layers of the appropriate
type. If you start from scratch without an open algorithm, the file
requester also appears for you to select an image.
the algorithm.
Most of the buttons on this toolbar duplicate options on the File
menu.
New
Identical to the File menu, New option. Opens the image in new
window.
Open
Identical to the File menu, Open option. Opens the image in the
currently active window.
This will overwrite any image currently being displayed in the
image window, and all changes will be lost.
Copy Window
Duplicates the current window and algorithm and runs the algorithm.
Save
Identical to the File menu, Save option.
164
ER Mapper menus and toolbars
Save As
Identical to the File menu, Save As option. It allows you to save the
current algorithm in any of the following formats:
•
ER Mapper Algorithm (.alg)
•
ER Mapper Raster Dataset (.ers)
•
ER Mapper Virtual Dataset (.ers)
•
ESRI BIL and GeoSPOT (.hdr)
•
Windows Bitmap (.bmp)
•
GeoTIFF/TIFF (.tif)
•
JPEG (.jpg)
•
UDF (.ers)
•
National Imagery Transmission Format (.ntf)
Print
Identical to the File menu, Print option.
Hand (Roam) Tool
Sets the mouse pointer to a hand. This allows you to drag the image
to a new position in the image window.
Zoom Tool
Sets the mouse pointer to a magnifying glass. You can zoom in and
out using the mouse.
ZoomBox Tool
Sets the mouse pointer to a magnifying glass with a box. You draw
a rectangle by dragging the mouse, and the image will zoom into
that area.
Pointer Tool
Sets the mouse mode to Pointer. The pointer shows an arrow. Allows
you to select objects in annotation, point to cells for viewing cell
coordinates and point to cells for cell coordinates and signatures.
Refresh
Forces ER Mapper to re-process the image. This is generally only
required to resume processing after you used the Stop Processing
button or Esc key to stop the processing. It is also very useful when
annotating the image, because it forces the image to redraw.
ER Mapper menus and toolbars
165
99% Contrast Enhancement
Applies a 99% clip to the final output transform for each active raster
layer and then processes the image.
Stop
Forces ER Mapper to abort the current image processing. After using
this button you must use the Refresh
resume the processing.
button for ER Mapper to
Common Functions
Image Display and Mosaic Wizard
Invokes the Image Display and Mosaic Wizard which allows you to
create and display algorithms and images in different modes. It also
automatically mosaics files of the same image type.
Image Balancing Wizard for Airphotos
Invokes the Image Balancing Wizard for Airphotos which performs
color balancing on a selected mosaiced image.
Annotate Vector Layer
Identical to the Edit menu, Annotate Vector Layer... option.
Opens the tools to enable you to edit a vector layer.
Contouring Wizard
Invokes the Contouring Wizard.
Ortho and Geocoding Wizard
Invokes the Geocoding Wizard.
Gridding Wizard
Invokes the Gridding Wizard which creates gridded raster images
from different types of input data.
Edit Algorithm
Identical to the View menu, Algorithm... option. Opens the
Algorithm dialog for you to edit the algorithm.
Load dataset
Identical to the Algorithm window, Load a Dataset button in the
Process Diagram.
166
ER Mapper menus and toolbars
Edit Formula
Identical to the Algorithm window, Edit Formula button in the
Process Diagram.
Edit Filter (Kernel)
Identical to the Algorithm window, Edit Filter (Kernel) button in
the Process Diagram.
Edit Realtime Sun Shade
Identical to the Algorithm window, Edit Realtime Sun Shade
button in the Process Diagram.
Edit Transform Limits
Identical to the Algorithm window, Edit Transform Limits button
in the Process Diagram.
Browse the ER Mapper Website
Opens the web browser installed on your PC and attempts to connect
to the ER Mapper website at http://www.ermapper.com.
Annotation
Setup Algorithm Page Size
Selects the File menu, Page Setup option.
Page Setup Wizard
Selects the File menu, Page Setup Wizard option.
Save Image to Clipboard
Saves the currently active image to the Windows Clipboard
Traverse Extraction
Selects the View menu, Traverse... option.
Scattergrams
Selects the View menu, Scattergrams... option.
Raster to Vector Conversion
Selects the Process menu, Raster Cells to Vector Polygons...
option.
Previous Zoom
Selects the Previous Zoom option from the View / Quick Zoom
menu. Re-displays image with previous zoom extents.
ER Mapper menus and toolbars
167
Zoom to Page Extents
Selects the Zoom to Page Extents option from the View / Quick
Zoom menu. Zooms image to include the page extents.
Zoom to Contents Extents
Selects the Zoom to Contents Extents option from the View /
Quick Zoom menu. Zooms image to include the extents of the
image on the page.
Aster
Opens the Aster Data Processing Wizard for processing Aster data
easily.
Batch Processing
Manage large algorithms
Opens the Large Mosaic Wizard which you can use to detect and turn
off algorithm layers that fall outside the image window extents.
Change Datum/Projection/Cell Size Wizard
Opens the wizard that you can use to define correct values in image
header (.ers) files. This is particularly useful for TIFF images with a
TIFW header file that dose not contain datum or projection
information.
Contact Sheet Wizard
Opens the wizard that you can use to prepare unregistered images
for mosaicing in ER Mapper
Map Collar Wizard
Open the Map Collar Wizard to automatically compute the collar clip
regions for maps such as USGS DRG topographic maps.
HDF Import Wizard
Open this wizard and use it to convert various HDF products into
native ER Mapper raster datasets (.ers) and compressed ECW
images.
Batch Reprojection Wizard
Opens the Batch Reprojection Wizard.
168
ER Mapper menus and toolbars
HGT Batch Import Wizard
Opens the HGT Batch Import Wizard for the import of Shuttle Radar
Topography Mission (SRTM) data in HGT format.
MapInfo .tab file Wizard
This utility extracts the information from .tab header files to create
ER Mapper (.ers) header files. It also allows you to enter datum and
projection information in the .ers files.
Classification
Landsat TM Wizard
Opens a wizard which creates one of several standard Landsat TM
algorithms. You must specify the Landsat TM image, and select the
type of algorithm required.
Define Regions
Identical to the Edit menu, Edit/Create Regions... menu option.
Edit Region details
Identical to the Edit menu, Edit Class/Region Color and Name...
menu option.
Regions to Vectors Conversion
Identical to the Process / Polygon<->Region Conversion menu,
Regions to Vector dataset polygons option.
Vectors to Regions Conversion
Identical to the Process / Polygon<->Region Conversion menu,
Vector dataset polygons to Regions option.
Calculate Dataset Statistics
Identical to the Process menu, Calculate Statistics option.
Calculates the image statistics.
Show Dataset Statistics
Identical to the View menu, Statistics / Show Statistics... option.
Displays the image statistics.
Area Summary Report
Identical to the View menu, Statistics / Area Summary Report...
option.
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169
Means Summary Report
Identical to the View menu, Statistics / Means Summary
Report... option.
Standard Deviation Summary Report
Identical to the View menu, Statistics / Standard Deviation
Summary Report... option.
Distance Between Means Report
Identical to the View menu, Statistics / Distance Between
Means Report... option.
Raster to Vector Conversion
Identical to the Process menu, Raster Cells to Vector Polygons...
option.
Supervised Classification
Identical to the Process menu, Classification / Supervised
Classification... option.
ISOCLASS Unsupervised Classification
Identical to the Process menu, Classification / ISOCLASS
Unsupervised Classification... option.
Scattergrams
Identical to the Process menu, Classification / View
Scattergrams option and View menu Scattergrams option.
Compression
Image Compression Wizard
Compresses images using the ECW V2.3 wavelet compression
technology.
Report on a compressed file
Returns information, including coordinate space, on the specified
compressed image file.
Start ECW Cache Monitor
Displays cache statistics during compression.
DEM
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Create Slope (degrees) Algorithm
Creates a Pseudocolor algorithm and adds the usercode
Slope_Degrees filter. In effect, the
examples\Data_Types\Digital_Elevation\Slope_degrees.alg
algorithm is constructed using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
Create Slope (percent) Algorithm
Creates a Pseudocolor algorithm and adds the usercode
Slope_percent filter. In effect, the
examples\Data_Types\Digital_Elevation\Slope_percent.alg
algorithm is constructed using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
Create Aspect Algorithm
Creates a Pseudocolor algorithm and adds the usercode Aspect filter.
In effect, the
examples\Data_Types\Digital_Elevation\Aspect.alg
algorithm is constructed using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
Contouring Wizard
Adds a contour layer to a display algorithm to generate contours
directly from an image or algorithm file.
ESG Color Enhance
Invokes the ESG Color Enhance toolbar.
ESG QuickStretch
Invokes the ESG QuickStretch toolbar.
ESG Utilities
Invokes the ESG Utilities toolbar.
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Invokes the Forestly Wizards.
Forestry
Landsat TM Wizard
Opens a wizard which creates one of several standard Landsat TM
algorithms. You must specify the Landsat TM image, and select the
type of algorithm required.
Highlight Water
Creates a pseudocolor algorithm using an image with 7 or more
bands. A formula is used to display water in white and everything
else in black.
Highlight Cloud
Creates a pseudocolor algorithm using an image with 7 or more
bands. A formula is used to display cloud in white and everything
else in black.
Highlight Vegetation
Creates a pseudocolor grayscale NDVI (normalized difference
vegetation index) algorithm with your image. The image must have
3 or more bands. This creates an
examples\Data_Types\Landsat_TM\Vegetation_NDVI.alg
algorithm using your specified image.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Vegetation Changes
Creates a pseudocolor algorithm that shows the vegetation changes
between two years, using classified imagery. The script asks for the
names of 2 classified scenes and an intermediate output algorithm
to produce, it creates the intermediate algorithm and then a final
algorithm.
Create Brovey Transform
Creates an RGB algorithm to merge two images together into a
single view. This is particularly useful for sharpening a low resolution
image with a high resolution one, for example Landsat TM sharpened
with SPOT Pan. This button creates the Example_Data_Fusion
algorithm about two images you specify.
See “Fusion” on page 23 of the ER Mapper Applications manual.
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ER Mapper menus and toolbars
Create RGB Algorithm
Creates an RGB algorithm. Where new Red, Green and Blue layers
are created, ER Mapper attempts to load bands 3,2,1 into these
layers respectively. If the bands have descriptions Red, Green and
Blue these will be used in the appropriate layers instead.
Create RGB Principal Components 123 Algorithm
Uses a multi-band image to create an RGB image with Principal
Component 1 in Red, Principal Component 2 in Green and Principal
Component 3 in Blue.
Create Slope (degrees) Algorithm
Creates a Pseudocolor algorithm and adds the usercode
Slope_Degrees filter. In effect, the
examples\Data_Types\Digital_Elevation\Slope_degrees.alg
algorithm is constructed using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
Create Slope (percent) Algorithm
Creates a Pseudocolor algorithm and adds the usercode
Slope_percent filter. In effect, the
examples\Data_Types\Digital_Elevation\Slope_percent.alg
algorithm is constructed using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
Create Aspect Algorithm
Creates a Pseudocolor algorithm and adds the ‘aspect’ filter which
calculates the aspect or direction of slope for a DEM. The numbers
output from the Aspect filter range from 0 to 361, where 0 indicates
a north facing slope. It is also useful to use a formula to emphasize
slopes facing a particular direction. This script creates the
examples\Data_Types\Digital_Elevation\Aspect.alg
algorithm using the image you specify.
See “Digital_Elevation” on page 311 in the ER Mapper
Applications manual.
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Show Tabular Data
Adds the dynamic link called Tabular Data / Table of data shown
as Circles on the Algorithm dialog box Edit / Add Vector Layer
menu to your algorithm and brings up a file chooser for you to
choose a .tbl table file.
Geophysics
Common Geophysical Images Wizard
Opens a wizard which creates a selectable common type of magnetic
and gravity image. You must specify the image to use.
Create RGBI Colordrape Algorithm
Creates an algorithm with RGB and Intensity layers.
The Intensity layer has a 45° sun shading applied and the
Pseudocolor layer uses the pseudocolor lookup table.
Create Pseudocolor Algorithm
Creates a pseudocolor algorithm
Create Ratio K/Th Algorithm
Creates a pseudocolor K/Th ratio algorithm. This constructs the
examples\Data_Types\Magnetics_And_Radiometrics\Radio
metrics_ratio_K_Th.alg algorithm using the image you specify.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Magnetics Fourier Wizard
Opens a wizard that applies a 1st Vertical Derivative or Reduce to
Pole FFT formula on a single band of an image. You must specify the
input and output dataset, and select the band and FFT Process to
apply.
Fast Fourier Transforms
Selects the Process menu, Fourier Transformations... option.
Traverse
Selects the View menu, Traverse... option.
Create 1Q Vertical Derivative Algorithm
Creates a grayscale pseudocolor algorithm using an intermediate
algorithm.
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ER Mapper menus and toolbars
Create 2nd Vertical Derivative Algorithm
Creates a grayscale pseudocolor algorithm using an intermediate
algorithm.
Create 3Q Vertical Derivative Algorithm
Creates a grayscale pseudocolor algorithm using an intermediate
algorithm.
Mineral Exploration Wizard
The wizard contains a collection of utilities and processes that are
commonly used in mineral exploration.
Many of the utilities in the Mineral Exploration Wizard require
that a C++ compiler be installed on the PC.
GIS
Raster to Vector Conversion
Selects the Process menu, Raster Cells to Vector Polygons...
option.
ARC/INFO Direct Access Link
Opens a dialog for you to select an ARC/INFO workspace.
Show Tabular Data
Adds the dynamic link called ‘Tabular Data / Table of data shown
as Circles’ on the Algorithm dialog box Edit / Add Vector Layer
menu to your algorithm and brings up a file chooser for you to
choose a .tbl table file.
MapInfo .tab File Reader
This utility extracts the information from .tab header files to create
ER Mapper (.ers) header files. It also allows you to enter datum and
projection information in the .ers files.
Minerals
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175
Common Geophysical Images Wizard
Opens a wizard which creates a selectable common type of magnetic
and gravity image. You must specify the image to use.
Landsat TM Wizard
Opens a wizard which creates one of several standard Landsat TM
algorithms. You must specify the Landsat TM image, and select the
type of algorithm required.
Create RGBI Colordrape Algorithm
Creates an algorithm with RGB and Intensity layers.
The Intensity layer has a 45° sun shading applied and the
Pseudocolor layer uses the pseudocolor lookup table.
Create Realtime Shade Algorithm
Creates a pseudocolor algorithm with realtime sun shading turned
on.
Create Ratio K/Th Algorithm
Creates a pseudocolor K/Th ratio algorithm. This constructs the
examples\Data_Types\Magnetics_And_Radiometrics\Radio
metrics_ratio_K_Th.alg algorithm using the image you specify.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Create Abrams Ratio Algorithm
Creates an RGB algorithm, using an image you specify, in which the
Red layer contains the ratio which highlights phyllosillicates (Band
5/Band 7), the Green layer contains the iron oxide ratio (Band
3/Band2) and Blue layer shows vegetation (Band 4/Band3).
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Create Clay Ratio/Magnetics Colordrape
Creates a Pseudocolor Clay over Magnetics Colordrape algorithm
from the current windows algorithm. If it cannot detect a valid image
it requests you to specify one.
RGB 741/Magnetics Colordrape
Creates an RGB 741/Magnetics Colordrape algorithm from the
current windows algorithm. If it cannot detect a valid image it
requests you to specify one.
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Create RGB Principal Components 123
Uses a multi-band image to create an RGB image with Principal
Component 1 in Red, Principal Component 2 in Green and Principal
Component 3 in Blue.
Oil and Gas
Common Geophysical Images Wizard
Opens a wizard which creates a selectable common type of magnetic
and gravity image. You must specify the dataset to use.
Create 3D Horizon
Creates a Pseudocolor/Height 3D Horizon algorithm from the current
windows algorithm and sets its description to “Seismic 3D TWT
colordraped”. If it cannot detect a valid image it requests you to
specify one.
3D Horizon Amplitude
Creates a Pseudocolor/Height 3D Horizon Amplitude algorithm from
the current windows algorithm and sets its description to “Seismic
3D Amplitude HSI/Height”. If it cannot detect a valid image it
requests you to specify one.
3D Shaded Horizon
Creates a Pseudocolor 3D Shaded Horizon algorithm from the
current windows algorithm and sets its description to “Seismic 3D
Shaded TWT colordraped”. If it cannot detect a valid image it
requests you to specify one.
Horizon Azimuth
Creates a pseudocolor algorithm which computes the azimuth
attribute of an horizon. It is displayed using the azimuth lookup
table: a 5-color Lookup Table representing the four primary
directions. The additional color is required as the Lookup Table must
wrap around; top and bottom colors must be the same.
The formula combines the easterly dip of the time data (dt/dx) with
the northerly dip of the time data (dt/dy) to obtain the azimuth.
See “Seismic” on page 329 in the ER Mapper Applications
manual.
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177
Horizon Dip
Creates an algorithm which computes the dip attribute of an horizon
and displays it as a grayscale image. The formula combines the
easterly dip of the time data (dt/dx) with the northerly dip of the
time data (dt/dy) to give the true dip.
See “Seismic” on page 329 in the ER Mapper Applications
manual.
Horizon IHS
Creates an HSI algorithm with TWT as the Hue and Intensity layers
and Amplitude as the Saturation layer.
Horizon RTS
Creates a pseudocolor algorithm with shading from a sun at an
azimuth and elevation of 45 degrees. A grayscale color table is used.
Radar Common
Remove Speckle Noise
Removes speckle noise from a radar image.
Remove Antenna Pattern Noise
Removes antenna pattern noise from a radar image.
Slant to Ground Conversion
Converts images from slant plane rather to ground plane
coordinates.
Layover and Shadow Map Generation
Generates a layover shadow map of the radar image.
SAR Image Simulator
Creates a simulated radar image from a DEM.
Texture Analysis
Carries out texture analysis of the radar image based on Gray Level
Co-occurrence Matrices (GLCMs) and produces output images whose
pixel intensity reflects the magnitude of that particular measure for
the corresponding pixel in the input image.
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ER Mapper menus and toolbars
Import Polarimetric Data
Imports polarimetric data from JPL file and outputs to a synthesized
ER Radar image.
Polarization Signature
Displays the polarization signatures of a polarimetric file.
Radar Filters
The Radar Filters toolbar allows you to add from the following filters
to process your radar data for speckle reduction:
Frost, Lee, K-Nearest Neighbor Lee, Symmetric Nearest
Neighbor Lee, Weighting (mtf), K-Nearest Neighbor
Weighting (mtf), Symmetric Nearest Neighbor Weighting
(mtf), Sigma
In addition, Add Texture Analysis Filter and Add SAR Image
Simulator Filter buttons are also provided.
Remote Sensing
Landsat TM Wizard
Opens a wizard which creates one of several standard Landsat TM
algorithms. You must specify the Landsat TM image, and select the
type of algorithm required.
Highlight Water
Creates a pseudocolor algorithm using an image with 7 or more
bands. A formula is used to display water in white and everything
else in black.
Highlight Cloud
Creates a pseudocolor algorithm using an image with 7 or more
bands. A formula is used to display cloud in white and everything
else in black.
Highlight Vegetation
Creates a pseudocolor grayscale NDVI (normalized difference
vegetation index) algorithm with your image. The image must have
3 or more bands.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
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179
Create Brovey Transform
Creates an algorithm to merge two images together into a single
view. This is particularly useful for sharpening a low resolution image
with a high resolution one, for example Landsat TM sharpened with
SPOT Pan.
See “Data_Fusion” on page 342 in the ER Mapper Applications
manual.
Create RGB Principal Components 123 Algorithm
Generates PC1, PC2 and PC3 and displays them as an RGB image.
Clay Ratio
Creates an RGB algorithm to highlight clays, phyllosillicates and
carbonates for Landsat TM images.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Iron Oxide Ratio
Creates an RGB algorithm to highlight iron oxides for Landsat TM
images.
See “Magnetics_And_Radiometrics” on page 325 in the
ER Mapper Applications manual.
Local Council Applications Wizard
This wizard contains utilities that could be used by local land
councils. It includes overlaying scanned maps on airphotos, and
change detection algorithms.
Land Application Wizard
The wizard contains a collection of utilities and processes that are
commonly used in land application.
Many of the utilities in the Land Application Wizard require that
a C++ compiler be installed on the PC.
Web Publishing
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ER Mapper menus and toolbars
Landsat Web Publishing Wizard
Publish your Landsat images on the internet or intranet so images
can be used by Web, GIS, CAD and office applications.
Wizards
Batch Script/Wizard Control
Opens a dialog which allows you to control script execution or select
scripts to run.
Image Compression Wizard
Compresses image files, including ER Mapper algorithms, using the
wavelet compression technique.
3-D Algorithm Wizard
Opens a wizard which creates a single surface 3D algorithm from a
raster and a height image which you specify.
Contouring Wizard
Adds a contour layer to a display algorithm to generate contours
directly from an image or algorithm file.
Landsat TM Wizard
Opens a wizard which creates one of several standard Landsat TM
algorithms. You must specify the Landsat TM image, and select the
type of algorithm required.
Map Collar Wizard
Open the Map Collar Wizard to automatically compute the collar clip
regions for maps such as USGS DRG topographic maps.
HDF Import Wizard
Open this wizard and use it to convert various HDF products into
native ER Mapper raster datasets (.ers) and compressed ECW
images.
MapInfo .tab File Reader
This utility extracts the information from .tab header files to create
ER Mapper (.ers) header files. It also allows you to enter datum and
projection information in the .ers files.
Common Geophysical Images Wizard
Opens a wizard which creates a selectable common type of magnetic
and gravity image. You must specify the dataset to use.
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181
Magnetics Fast Fourier Transformations Wizard
Opens a wizard that applies a 1st Vertical Derivative or Reduce to
Pole FFT formula on a single band of an image. You must specify the
input and output dataset, and select the band and FFT process to
apply.
Page Setup Wizard
Interactively leads you through setting up a page, including the
addition of an optional vector layer.
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ER Mapper algorithms, filters and
formulae
In addition to the multiple wizards outlined in Chapter 15, ER Mapper
provides numerous ready-to-use template algorithms, filters and
formulae which will cover most of the tasks that you would
commonly like to carry out while processing your images.
Refer to the ER Mapper Application manual, Part Four - Supplied
Processing, “Supplied Algorithms” and “Supplied Filters” for
detailed description of each.
Algorithms
You use ER Mapper's graphical user interface to define your list of
processing steps, and you can save the steps in an algorithm file on
disk. An algorithm file can store any of the following information
about your processing:
•
Names of image datasets to be displayed.
•
Subsets of the image datasets to be processed (zoomed areas).
•
Bands in the image datasets to be processed.
•
Brightness and contrast enhancements (Transforms).
•
Filtering to be applied to the data (Filters).
•
Equations and combinations of bands or images used to create
the output image (Formulae).
•
Color mode used to display the data (Pseudocolor, Red Green
Blue, or Hue Saturation Intensity).
•
Any vector images, thematic color, or map composition layers to
be displayed over the raster image data.
•
Definition of a page size and margins (used for positioning the
image on a page for creating maps and printing).
By being able to apply a set of processing steps as a single entity,
the complexity often associated with digital image processing is
greatly reduced. In addition, you gain tremendous savings in disk
space, since you do not need to store intermediate processed copies
of your original data on disk.
Building Algorithms in
ER Mapper
There are two primary ways to build a processing algorithm in
ER Mapper:
ER Mapper algorithms, filters and formulae
183
Using Algorithms as
Templates
•
Use the Algorithm window to add the desired types of layers,
load images, and specify processing steps for each layer.
•
Click a toolbar button to have ER Mapper automatically create an
algorithm for you. In this case, ER Mapper adds the appropriate
layers to the Algorithm window, prompts you to load an image,
and possibly other options as well.
Once you have saved your processing instructions as an algorithm
file, you can use the algorithm as a “template” to easily apply the
same processing to different images. Any algorithm can be used as
a template, but ER Mapper also provides many template algorithms
for common tasks. These include common display techniques (RGB,
single band grayscale, etc.), writing processed image files to disk,
and saving algorithms as “virtual datasets.” Using template
algorithms saves time.
Typical use of the supplied algorithms is to load the algorithm and
change the image to your own image, and then click on the Refresh
Image with 99% clip on limits
with 99% transform clipping.
button to run the algorithm
The processing carried out by algorithms depends on the type of data
and the desired result. For example, the Landsat_TM/NDVI
algorithm computes the Normalized Difference Vegetation Index
(NDVI) from the Landsat TM imagery.
The supplied algorithms are designed as starting points for creating
your own commonly used algorithms. They were created using the
standard ER Mapper user-interface - they are not ‘hard coded’ into
ER Mapper.
The algorithms and images supplied with ER Mapper are divided into
sections, typically based on the type of data or the type of
processing. The different sections are located in the following
directories under examples.
184
•
Applications: Specific application examples; e.g., Mineral
•
Data_Types: Examples which illustrate the use of a specific type
•
Functions_And_Features: Examples which illustrate a particular
ER Mapper function or feature.
•
Shared_Data: Image datasets which are shared by one or more
of the other examples directories.
Exploration, Oil and Gas Exploration etc.
of data.
ER Mapper algorithms, filters and formulae
•
Miscellaneous\Templates: Designed as templates to be used to
create virtual datasets or images. Load the template algorithm,
change to the new images, zoom to all datasets (if entire
coverage is desired), and then save the resultant algorithm as a
virtual dataset or as a real image. Most template algorithms do
not have a final transform - this ensures that the data being
processed is not modified by the template algorithm.
The example algorithms are designed to be used as-is. Simply load
the algorithm, change the image, and click on the Refresh image
with 99% clip on limits
button.
In addition to the example algorithms loaded with ER Mapper you
can also choose to load other application example algorithms during
installation. These are inserted into the appropriate examples
directories.
Filters
A filter (or kernel) is defined in ER Mapper to be an operation that
processes a cell based on the cells which are surrounding it in the
spatial domain. Filters supported are convolutions (e.g., average
filters) and threshold filters (convolution with threshold).
Filters are applied by choosing the Filter
button from the
process diagram in the Algorithm dialog box for the current layer.
Filters are text files and are located in the kernel directory. Please
refer to kernel directory for details about a particular filter.
A number of common filters are supplied with ER Mapper. Additional
convolution or threshold filters can be created in the form of
numerical arrays, for example, to increase the dimension of a
smoothing filter.
Any number of Filters may be cascaded.
As well as the filters provided with ER Mapper, it is important to note
that it is possible to use other types of filters.
See Customizing ER Mapper manual for more information on
filter formats.
The filters supplied with ER Mapper are divided into the following
sections, typically based on the type of data or the type of
processing:
•
DEM filters
•
Edge filters
•
Gaussian filters
•
Geophysics filters
ER Mapper algorithms, filters and formulae
185
Formulae
•
High pass averaging filters
•
Low pass averaging filters
•
Ranking filters
•
SAR filters
•
Seismic filters
•
Standard filters
•
Sunangle filters
•
Usercode filters
The Edit Formula
button is used in raster layers to define
and include mathematical functions which combine multi-band data
on a point by point basis. Formulae may, for example, include ratios,
differences or principal components or even complex logical
conditions and region statistics. Sometimes formulae are used to
process single band images, for example, as an alternative to
transforms or to implement raster GIS functions, such as masking
regions using “if” tests.
A number of common formulae have been supplied with ER Mapper
to accomplish processing such as vegetation indexing, supervised
classification, ratios, principal components and mosaicing.
To create a formula, first define a “generic” formula without
specifying the data bands to be processed. Then attach particular
bands of data to create a “specific” formula. For example, a simple
ratio with the generic form “INPUT1/INPUT2” with bands attached
gives the specific formula “B4: 0.83 um / B3:0.66 um”.
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ER Mapper algorithms, filters and formulae
ER Mapper Wizards
This section provides a brief overview of the wizards incorporated
into ER Mapper to make many of your complex or common image
processing tasks as simple as clicking through a small number of
steps. The wizards allow even a lay user to undertake complex image
processing tasks while providing an experienced user with a
convenient tool to make those tasks simple and fast.
The wizards and their uses are described in detail in the online
ER Mapper User Guide.
A brief description of each of the wizards is given here:
3-D Algorithm
Wizard
This wizard creates a single surface 3D algorithm from a raster and
a height image which you specify.
The wizard can be opened by clicking on the 3D Algorithm Wizard
button on the Wizards toolbar.
The opening page asks you to select the type of 3D algorithm that
you want to produce - Pseudo Color or RGB.
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187
The next page allows you to choose the raster and height datasets
and also to specify the color table if you selected pseudo color.
ASTER Data
Processing
Wizard
The ASTER Data Processing Wizard enables you to process ASTER
data (14/15 bands) easily and reliably. The wizard can be used to
reduce noise contributed from topography, instruments and sun
illumination. Synthesized spectrum of surface cover types in the
SWIR from the noise reduced ASTER data can be compared with the
library spectrum and minerals/rocks can be identified. The Wizard
also incorporates the Decorrelation Stretch algorithm to reduce the
inter-channel correlation of the closely spaced SWIR and TIR,
enhancing the subtle information for better interpretation and
classification. Also included are modules for mapping regions of
interest, mapping of surface types and classification.
This wizard is intended for use by those who already have a good
knowledge of the processes involved. This description is limited to an
outline of the facilities included.
For information about training courses on the ASTER Data
Processing Wizard, please contact your nearest Earth Resource
Mapping office or reseller. Alternatively you can go to the
www.ermapper.com web site.
1. To activate the wizard, click on theASTER Data Processing Wizard
button located on the Aster toolbar. This will open the first
page of the wizard.
If the Aster toolbar is not visible, select it from the Toolbars menu
list.
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ER Mapper Wizards
2. Follow the instructions on the pages and click the Next> button to
continue.
Processing modules
The wizard consists of eleven modules that you can access via the
main page:
Separate 14-band ASTER to 3 Groups
Separate the ASTER data into 3 groups (VISNIR,
SWIR and TIR).
Noise Reduction of SWIR & TIR
Reduce noise in ASTER SWIR and TIR data.
Data Integration (VISNIR, SWIR & TIR)
Integrates different types of ASTER data into a
single dataset, which is then used in comparison
utilities.
Display Pseudocolor or RGB image
Select a single band or 3 bands of ASTER data and
display as pseudocolor or RGB image.
Ratioing (Ratioed Pseudocolor or RGB)
Generate ratio images of ASTER data.
Defining Region of Interest
Define region of interests.
Mapping Region of Interest
Map region of interest.
Mapping Common Surface Cover Types
Map common surface cover types such as water,
vegetation and bare ground.
Log Residual (SWIR)
Apply log residual algorithm to reduce noise from
topography, instrument or sun illumination.
Decorrelation Stretch
Reduce the inter-channel correlation and stretch the
dynamic range.
Classifications
Classify ASTER data in separate groups or
combined.
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189
Separate 14-band ASTER to 3 Groups
Use this module to separate a 14/15-band ASTER data file into
VISNIR, SWIR and TIR groups. These data groups are saved as three
separate files with _VISNIR.ers, _SWIR.ers, _TIR.ers extensions
respectively, in the specified directory. If stereo pair images are
included (3N, 3B) for NIR, then _VISNIR.ers will have 4 bands.
Band descriptions are taken from the original file and the original
data type and format are maintained.
This module will only work on files with ER Mapper (*.ers)
format. You can import ASTER (.hdf) files into ER Mapper using
the HDF Import Wizard from the Wizards toolbar.
Noise Reduction of SWIR & TIR
Noise Reduction
Noise Reduction - SWIR
Noise Reduction - TIR
This module allows you to reduce noise in ASTER SWIR and TIR data.
Noise could be due to the low signal-to-noise ratio at lower frequency
ranges (longer wavelengths) of the electromagnetic spectrum. The
noise reduction algorithm reduces noise by applying standard
deviation filters on the principal components (PC) of the SWIR and
TIR and inverting them back to the original space. Since lower PC
components accumulate noise, options are given to reduce noise in
the lower PC components. Depending on the noise, different levels
of standard deviation filters are provided for selection. If no noise
reduction is required, apply the 0.0 Standard Deviation filter. The
highest is the Standard Deviation filter of 1.6.
Data Integration (VISNIR, SWIR & TIR)
Integrate VISNIR, SWIR & TIR
Integrate VISNIR & SWIR
Integrate VISNIR, SWIR & TIR
Use this module to integrate three different ASTER data groups (3/4band VISNIR, 6-band noise- reduced SWIR and 5-band noisereduced TIR) into one dataset. This can be useful for further
processing, such as in classification.
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Display Pseudocolor or RGB image
Display pseudocolor or RGB
Display pseudocolor image
Display RGB image
Display PC123
(RGB)
This module allows you to select a single band or 3 bands of ASTER
data and display them as Pseudocolor (single band) or RGB images
(3 bands).
Ratioing (Ratioed Pseudocolor or RGB)
Ratioing (Pseudocolor or RGB)
Ratioing pseudocolor
Ratioing RGB
Use this module to generate ratio images of ASTER data. You can
ratio 2 ASTER bands and display the ratioed image in pseudocolor or
you can ratio 6 bands and display them as an RGB image.
Defining Region of Interest
This module allows you to define a Region of Interest (ROI).
Mapping Region of Interest
This module allows you to map the Region of Interest (ROI) defined
in the ‘Defining Region of Interest’ module.
Simply load your dataset with the Region of Interest (ROI). The
module will map the Area of Interest for you. You can save the
output data as a virtual dataset. Areas outside the regions will have
null values and thus will be excluded when statistics are calculated
for the dataset. If you want to exclude water areas from the
statistics, you can also define the water regions and nullify it.
Exclusion of water regions has not been automated in the Wizard and
needs to be done manually using ER Mapper.
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Mapping Common Surface Cover Types
Mapping common surface cover types
Water
Vegetation
Water and bare ground
Water, vegetation & bare ground
Vegetation (4 NVDI)
This module allows you to mapping common surface cover types.
Log Residual (SWIR)
This module allows you to apply the log residual algorithm, which
reduces noise from topography, instrument and sun illumination
(1Green and Craig, 1985). The resultant data is assumed to be more
representative of the soils or lithologies of the exposed areas. Hence,
spectrum generated from log residual applied data will be more
comparable to the library spectrum.
Decorrelation Stretch
This module allows you to reduce the inter-channel correlation and
stretch the dynamic range to the full extent, which enhances the
color variation and improves the visualization for interpretation
(Gillespie et al., 1986, Gillespie, 1992). The module requires
Microsoft Visual Studio 2005 to be installed in your computer and the
environment variables set up properly.
Classifications
Classifications
Unsupervised
Supervised
Scattergram
This module allows you to classify ASTER data using either VISNIR,
SWIR or TIR separately or combined.
1. Green, A.A and Craig, M.D., (1985)."Analysis of aircraft spectrometer data with logarithmic residuals.""JPL Publ. 85-41, pp. 111-119.
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ER Mapper Wizards
Refer to section ASTER Data Processing Wizard in the online
user guide for further information.
Change
Projection/Datum
/Cell Size Wizard
This wizard was designed to accommodate TIFF/TFW images that do
not have Projection/Datum information. When the Projection and
Datum of an image is unknown, ER Mapper defaults to RAW/RAW or
WGS84/LOCAL, which may not be correct. Also, if the TFW file
specifies the Cell Size to be in feet, ER Mapper will incorrectly
assume it to be in meters.
1. Open the wizard by clicking on the Change
Projection/Datum/Cell Size for many images
button in
the Batch Processing toolbar.
This wizard does not reproject your images. It is used to change
image header information to reflect the correct information.
Using this wizard will change your image headers. Use carefully.
This wizard modifies the ERS header file with the image with
Projection, Datum, and Cell Size information you specify. It creates
a new ERS header file if one does not exist. ER Mapper uses this
information in preference to that included in a TFW file.
ER Mapper always records cell size in meters or in degrees,
never in feet. Some TFW files record the cell size in feet, but
there is no way of detecting if the size should be in feet or
meters. ER Mapper may incorrectly assume the size is in meters
when it was in fact in feet.
This wizard enables you to convert the wrong cell size (feet being
treated as meters) into the correct units.
Common
Geophysical
Images Wizard
ER Mapper Wizards
This wizard creates a selectable common type of magnetic and
gravity image. You specify the image dataset to use.
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The Common Geophysical Images Wizard
button is found
on the Geophysics, Minerals, Oil and Gas and Wizards toolbars.
Select the image that you want to create, load the dataset and click
on Finish.
The data used needs to be gridded or imported before using this
wizard.
Contact Sheet
Wizard
If you want to mosaic a number of unregistered (non-geocoded)
images, you can use this wizard to create and edit .ers header files
that provide the necessary offsets for placing them in the mosaic.
The Contact Sheet Wizard enables the user to bypass the tedium of
"hand-registering" non-geocoded imagery as part of the process of
creating a "contact sheet" mosaic.
The following is a typical workflow procedure for creating a mosaic
of unregistered images.
Preparing the images
Copy all the images to be mosaiced into the same directory.
The images must all be in the same format.
If necessary, rename the image files so that the wizard will place
them in the required order.
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ER Mapper Wizards
Running the wizard
1. Start the wizard by clicking on the Create a Contact Sheet mosaic
button on the Batch Processing toolbar.
This will open the information page of the wizard.
2. After reading the description and warning on the wizard page, click
Next > to continue or Cancel to close the wizard. Follow the
instructions on the following pages to finish and display the mosaic.
The Contact Sheet Wizard creates or modifies .ers headers for all
images in a directory so that they will form a "contact sheet" mosaic
of images.
DO NOT run this wizard on geocoded imagery as it will overwrite
any geocoding information already present (specifically, X and Y
offset locations) in the ERS file, resulting in the loss of extents
information. The wizard does not display any warning.
The wizard can handle any image format supported by ER Mapper,
so you can use it for JPEG's, TIFF's, ERS files, ECW files, etc. If there
is no existing ERS file for the specified image, the wizard will create
one.
After running the wizard, you can use the Image Display and
Mosaic Wizard to create the actual mosaic.
Restrictions
ER Mapper Wizards
The wizard uses a fairly simple method to calculate the extents and
positions of the images in the mosaic. It, therefore, has the following
usage restrictions:
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•
All the images should have the same dimensions, otherwise there
could be some overlapping. This could result in you having to
manually edit some of the registration information. You do not
have any control over the number of rows and columns of images
in the output mosaic. The wizard will always try to arrange them
in a square. For example, 4 images would be arranged in a 2 * 2
matrix, 6 images in a 3 * 2 matrix, 8 images in a 3 * 3 matrix
with only two in the third row etc.
The wizard arranges the images row by row in alphabetical order
of file name. If you want the images to be in certain positions,
you must name them accordingly. An image named
image_10.jpg will be placed before image_2.jpg.
•
It is not possible to specify a margin around each image. You
would have to manually edit the header (.ers) files to do this.
Refer to the“Contact Sheet Wizard” chapter in the ER Mapper
User Guide for more information.
Contouring
Wizard
This wizard adds a contour layer to a display algorithm to generate
contours directly from an image or algorithm file.
1. You can invoke to Contouring Wizard by either clicking on the
Contouring Wizard
button on the Common Functions
toolbar, or by selecting the Contours dynamic link from the Edit /
Add Vector Layer menu in the Algorithm dialog box.
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ER Mapper Wizards
2. Select the file name and band of the image to contour.
3. Enter or select the path and name of the vector (.erv) file to save
the contours to.
Follow the instructions on the wizard dialog pages. Use the <Back
and Next> buttons to navigate through the wizard,
If you want to view the contours in 3D or export the contour vectors
to another application, enter or select the path and name of the
vector (.erv) file to save the contours to.
4. Click on the Save button to save the vector file.
5. Click on the Finish button to draw the contours on the image and
exit the wizard, or the Cancel button to exit the wizard without
drawing the contours.
The Contouring Wizard automatically adds the contour layer to
the currently active algorithm. You can save the algorithm with
the new contour layer by clicking on the Save Algorithm button
or selecting Save from the File menu.
The ER Mapper Contouring Wizard generates contours directly from
an image (or algorithm) file. This unique and powerful feature
enables you to adjust the contour styles and see the difference
immediately. It is not necessary to save the contours to a vector file
because ER Mapper regenerates the contours every time the
algorithm is run. You will, however, need to save the contours to a
vector file if you want to use ER Mapper to view them in 3D, or if you
want to export them for use in another application.
The Contouring Wizard features can be summarized as follows:
ER Mapper Wizards
•
Datasets, algorithms and virtual datasets can be contoured.
•
You need only select the data source and the band, and
ER Mapper will automatically create the contours.
•
You can let ER Mapper set the parameters or you can specify
them yourself.
•
You can set the contour start value and interval, contour labels
and contour color, line style and line width.
•
You can either have all contours with same width and a solid line
style, or primary contours at specified intervals with secondary
contours between them. You can then opt to have the primary
contours wider and select a different line style for the secondary
contours.
•
You can save the contours to a vector (.erv) file.
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If you use the Contouring Wizard on images larger than 2000 *
2000 cells, it will downsample the image to 2000 * 2000 cells.
Refer to the Gridding and Contouring chapters of the
ER Mapper User Guide to learn more about contouring and the
Contouring Wizard.
ESG Wizards
The following ESG (Earthstar Geographics) wizards have been
integrated into ER Mapper to provide a powerful set of tools aimed
at increasing productivity with an emphasis on automating common
tasks.
•
ESG Color Enhancement Wizards – for tasks such as color
draping and resolution enhancement
•
ESG QuickStretch Wizards – for immediate application of
contrast stretches including Histogram and Gaussian
equalizations
•
ESG Utilities – automation and batching of common tasks such
as importing/exporting, printing and rectification
•
ESG SFIM Pan Sharpen Wizard – improved algorithm for pan
sharpening a lower resolution multispectral image with a higher
resolution panchromatic image
•
ESG NED Import Wizard – import USGS National Elevation
Dataset (NED) DEM binary format into ER Mapper’s ERS format
For more information about updates to the ESG (Earthstar
Geographics) wizards refer to the ESG Wizards section of the online
ER Mapper User Guide.
Gridding Wizard
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This wizard generates gridded raster images from point, line or
polygon data.
ER Mapper Wizards
1. Select Gridding Wizard... from the Process menu or click on the
Gridding Wizard
button on the Common Functions toolbar
to open the Gridding Wizard.
2. You can choose to start a new grid project or modify an existing one.
Click on Next>.
3. Use the Next> button or follow the tab sequence to proceed through
the wizard.
Follow the instructions on the wizard pages to complete the following
steps:
•
Choose the input data sources
•
Setup the output bands by allocating the input sources to them.
•
Select the gridding method to be used (Triangulation or Minimum
Curvature)
•
Setup the output information and create the gridded image file.
On the final tab page, Create Grid, enter the name of the file to
which the gridded image is to be saved, and click on the Finish
button to exit the wizard.
You can save the project file to re-generate a gridded image
without having to re-enter the specifications.
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The ER Mapper Gridding Wizard creates a project file which specifies
how one or a number of input data sources are to be used to develop
a raster gridded image file. It then uses this, or a previously saved,
project file to create the gridded image file.
Project (.egp) File
Input
data
sources
Project File
Gridding
Wizard
Output raster
gridded image
(.ers) file
The Gridding Wizard requires you to specify a Project File before it
can perform the gridding. If you do not specify the name of an
existing project file, the Gridding Wizard will create a new one for
you to enter the necessary specifications. You can save this project
file for future use.
You can use a previously saved Project File to re-generate a gridded
output file without having to re-enter the specifications. You can also
edit existing project files to create new gridded images.
Input sources
You can use point, line and polygon data from one or more sources.
ER Mapper will automatically handle any of the input formats listed
below.
•
Generic ASCII XYZ
•
DXF
•
USGS contour format (DLG-3)
•
Any raster formats directly readable by ER Mapper (including
.ers)
•
ER Mapper .erv format
An ER Mapper point extractor converts the above formats into XYZ
triplets, which is the required format for the gridding process.
Output gridded image
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The ER Mapper gridding facility differs from many other products in
that you can use it to generate a multiband raster image file. Where
you have specified multiple input sources, you can select one of the
following options:
•
Each input source goes to its own output band, thus creating a
number of thematic overlays.
•
All input sources are combined into a single mosaiced output
band.
ER Mapper Wizards
•
You can customize the output by assigning specific input sources
to any number of output bands.
You can then collectively or separately specify the gridding method
(i.e. Triangulation or Minimum Curvature) for each output band.
To learn more about gridding or the Gridding Wizard, refer to the
Gridding and Contouring chapters of the ER Mapper User
Guide.
HDF Import
Wizard
This wizard allows you to convert various HDF products into native
ER Mapper raster datasets (.ers) and compressed ECW images.
Products supported by the HDF Import Wizard are identical to those
supported by the HDF Raster Translator. The supported HDF-4
products are:
•
Aster Level1A, Level1B, DEM, Level 2 Decorrelation Stretch,
Brightness, Temperature, Emmisivity, Surface reflectance,
Surface radiance and GDS datasets
•
MODIS Level1A, Level 1B, Level 2, Level 2G, Level 3, Level 4
•
Landsat 7 ETM+ Level1R and Level1G
•
SPOT Vegetation
•
EODIS Version 0 Basic raster
1. You can start the wizard by clicking on the HDF Import Wizard
button on the Batch Processing or Wizards toolbar.
The first page of the wizard will open.
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201
2. Select the options on this page and click Next> and follow the
instructions on the subsequent screens. The screens will vary
according to the options you choose.
3. In the next window, specify the input and output dataset filenames
and click Next>.
You can also select what type of output files you wish the wizard to
produce. Select Produce compressed ECW image if you wish the
wizard to compress the input file and produce an Enhanced
Compression Wavelet file (.ecw). Select Produce .ers raster
image if you wish the wizard to produce a native ER Mapper raster
dataset (.ers).
Select both options if you want both types of output to be
produced. At least one form of output must be selected.
Select the Include sub-directories option if you would like the
wizard to import files from sub-directories of the input directory.
Output files will have "_imported" appended to the filename before
the extension. This allows the output directory to be identical to the
input directory if required.
4. Press Next> to go to the next page.
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ER Mapper Wizards
The sequence of pages shown here is that for a single-file import
option. If you have chosen multiple-file import, the pages will look
different to those shown in this documentation; however the options
requested are identical. Additional notes are included in those pages
that relate to a multiple-file import.
You can select your compression options: Color (RGB), Grayscale or
Multiband, and also enter the target compression that you would like
to achieve.
By default, the compressor works on the ‘Best’ option. Select
Compress for Internet usage if you want smaller block sizes for
quicker transmission over the Internet.
Currently, the Fast and Internet options produce identical
results, i.e., x,y block sizes of 64,64. This will change in a future
enhancement. The Best option produces an x,y block size of
512,256.
Select Rotate image to True North to use the erswarp module to
rotate the image back to True North. This allows mosaics to be
produced from path-oriented datasets.
5. Selecting Use a null cell value? and specifying a value, will set the
null cell value of the raster dataset (.ers).
When performing a multiple-file import, these options will be
applied to all files being imported.
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203
When performing a multiple file import, the contents/status
window will display the contents of the first file found in the input
directory. An attempt will then be made to import the bands
chosen on the band selection page, from all files. It is assumed
that a multiple-file import will be performed on a directory that
contains a single HDF product type.
Refer to the ER Mapper User Guide for details of this wizard.
Image Balancing
Wizard
This wizard automatically balances and clips the images in the
currently active image window to produce seamless mosaics.
1. To use the Image Balancing Wizard for Airphotos, first open the
images or mosaic to be balanced and then start the wizard.
2. Click on the Image Balancing Wizard for Airphotos
button
on the Common Functions toolbar to open the wizard.
3. Click on the Next> button, and Next> again on the following screen
to carry out an analysis on the images to be balanced.
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ER Mapper Wizards
ER Mapper carries out the analysis and brings up the display options
window.
4. Choose how you want the images balanced. You can also chose to
correct for water areas if there are large areas of water in your
image. An option exists to display the clip regions as vector overlays.
5. Click on Next> to display your image.
6. After rendering the balanced image you are presented with the
option of color matching the mosaic. Choose your option and click on
Next> to render the image with color matching.
While the wizard is particularly suited to balancing airphotos, it
will balance any kind of data, including non-eight bit. You can,
for example, use it to scale and mosaic seismic surveys and
magnetics data.
The wizard works best on mosaiced images when there is an
overlap between each image. Do not trim the images before
balancing them.
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205
Image mosaics, particularly airphotos, can have problems where
variations in the individual mosaiced images result in the images not
blending in with one another. This creates an undesirable
“patchwork” effect. These variations can be caused by dark rims
around the individual images, changes in atmospheric depth, camera
lens settings etc. This effect can minimized by balancing the
individual images or the mosaiced image.
Unbalanced image mosaic
Balanced image mosaic
The ER Mapper Image Balancing Wizard For Airphotos automatically
balances image mosaics. It does this by:
•
Detecting black or white edges of airphotos
•
Detecting variations across images due to camera lens variations
and changes in atmospheric depth across images.
•
Detecting hot spots (sun glint).
The Image Balancing Wizard For Airphotos balances the images
by applying radiometric changes across their output display. You
should, therefore, not use it on images where radiometric
changes would modify the meaning of the data. For example,
you should not normally use the Image Balancing Wizard For
Airphotos on Digital Elevation Model (DEM) data.
Refer to the “Image Balancing Wizard for Airphotos”
chapter of the ER Mapper User Guide for more information.
Image
Compression
Wizard
206
The Image Compression Wizard enables you to save an image in
ECW compressed format. It provides a User Interface for you to
specify a target compression ratio.
ER Mapper Wizards
1. You can access the Image Compression Wizard by selecting
Save as Compressed image... from the File menu or by clicking
on the Image Compression Wizard button
on the
Compression or Wizards toolbar.
2. Select the output format (ECW or JPEG 2000) and the source of the
images to be compressed and click on the Next > button.
Choose one of the following options:
Use the current algorithm window Compress directly from the current image window algorithm
which details the files to compress.
Select input images to compress
Compress from a file stored on disk
Batch compress multiple images
Compress a number of individual images by specifying the
directory in which their files are stored.
An easy way to compress imagery is to open an image window,
set up the results to your satisfaction, and then select the
current image window as input for the Compression Wizard.
Follow the instructions and the wizard will report the extent of
compression that has taken place when it has finished.
When you specify the input images to compress, you may specify an
ER Mapper smart data algorithm as the input to be compressed.
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207
In addition to using an algorithm as the source image to be
compressed, you can specify any other file format supported by
ER Mapper, such as ESRI BIL, TIFF, JPEG as the input.
You will be shown the anticipated output file size based on your
target compression ratio, and you can adjust the compression ratio
to select a different output file size. A larger compression ratio
results in a smaller output file.
The desired compression ratio to use: typically between 20:1 to
50:1 for color compression, and 10:1 to 20:1 for grayscale
compression.
The Compression Wizard will then compress your input images,
giving you a graphical progress report while compressing. Once the
file has been compressed, you will be informed of the time taken to
compress, and the actual compression ratio achieved.
ER Mapper will save the compressed image as a header (.ers) and a
compressed data (.ecw) file. You can use File / Open or one of the
wizards to open the header (.ers) file just like any other image file
supported by ER Mapper.
If you are saving an ER Mapper algorithm as a compressed
image, you can minimize the resultant file size by turning off or
deleting algorithm layers that fall outside the image window
extents. The Large Mosaic Wizard will do this for you quickly and
easily.
Refer to section Large Mosaic Wizard of this chapter for more
information.
The header (.ers) file is optional because the data (.ecw) file
also contains georeferencing information.
The ER Mapper compression (ECW) facilities enable you to
substantially reduce the file sizes of your images without any
noticeable deterioration in quality. The latest compressor version,
ECW V2.3, creates even higher quality compressed images with a
corresponding improvement in performance.
The ECW compressed image file will include georeferencing
information in GeoTIFF or TFW (TIFF world) files.
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ER Mapper Wizards
You can use the ER Mapper Mosaic Wizard and Balance Wizard to
create an algorithm that creates a seamless and balanced mosaic of
input airphotos, which can then be compressed out to a single
compressed image file. See Chapter , “” for a worked example of
compressing a mosaic.
As algorithms perform processing on the fly (without creating
intermediate disk files), you can go from the collection of input files,
to a resultant mosaiced, balanced and compressed image file without generating any intermediate files.
For more information on image compression and use of this wizard,
please refer to the online ER Mapper User Guide Part Two Algorithms and Images, “Compressing images”.
Image Display
and Mosaic
Wizard
This wizard allows you to enter the file names of raster and vector
images, which it then displays and/or mosaics to your requirements.
The Image Display and Mosaic Wizard is a powerful multi-purpose
tool that performs most of the common functions done via the
Algorithm dialog box. It leads the user interactively through a large
variety of image manipulation tasks.
1. You can start the Image Display and Mosaic Wizard by clicking on the
Image Display and Mosaic Wizard
button on the Common
Functions toolbar.
If there is an image window already open, ER Mapper will display the
main Image Display and Mosaic Wizard dialog box. You can
select one of three options:
ER Mapper Wizards
•
Display in a new window
•
Add more to this window
209
•
Change display in this window
If there is no image window already open, ER Mapper will not display
the main wizard dialog box but goes straight to the Display in a
new window option.
Proceed through the wizard by following the instructions on the
dialog boxes.
Use the buttons at the foot of the wizard dialog boxes to navigate
around the wizard.
•
< Back: Go back to the previous dialog page. This is useful if you
need to change an earlier setting. This button is unavailable if
there is no previous dialog box.
•
Next >: Go to the next dialog page to either set some more
parameters or to begin processing. This button is replaced by the
Finish button in the final dialog box.
•
Cancel: Close the Image Display and Mosaic Wizard and remove
all changes made during that wizard session. This allows you to
back out cleanly if you have made an error.
•
Finish: Close the Image Display and Mosaic Wizard and retain all
changes made during that session. This button is only available
on the final dialog box.
You can now select the dataset (image, algorithm or vector file) that
you wish to display. You can also set the view mode to 2D or 3D. If
you select Mosaic all files of this type, ER Mapper will search all
files of the same type in that directory and mosaic them.
Click on the Finish button to exit the wizard, or the Cancel button
to “back out” of the wizard.
You can mosaic images quickly and efficiently by selecting the
Mosaic all files of this type option.
While new users will find its interactive and intuitive mode of
operation extremely helpful, experienced users will also benefit from
its time and effort saving properties.
If you have already created a number of algorithms or images, each
defining a different view of your data, you can use the Image Display
and Mosaic Wizard to combine these in a single window using
multiple surfaces.
One of the best features of the Image Display and Mosaic Wizard is
the way it efficiently creates image mosaics with minimal user
intervention.
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ER Mapper Wizards
To create an image mosaic, all you have to do is enter the name and
location of an input file, and the wizard will automatically search for
files of the same type to mosaic. You can constrain its search to the
same directory, include sub-directories and even include other
directories at the same level. You can also define the type of files to
mosaic and properties such as feathering and stitch regions.
Refer to the “Image Display and Mosaic Wizard” chapter in
the ER Mapper User Guide for more information.
Land Applications
Wizard (LAW)
This is a comprehensive utility that consolidates more than forty
separate batch routines for processing Aerial Photographs, SPOT
(Panchromatic and Multi-Spectral), Landsat Thematic Mapper (TM)
and Digital Elevation Model (DEM) imagery within ER Mapper.
1. To activate the wizard, click on the Land Applications Wizard
button located on the Remote Sensing toolbar.
2. Follow the instructions on the pages and click the Next> button to
continue.
The Display HSI wheel option opens an image window with an
RGB algorithm displaying an HSI Color Wheel. You can use this
to assist you in RGB and HSI color composite interpretation.
ER Mapper Wizards
211
delete_windows.erb is a useful script for closing down the
multiple windows created by the Land Application wizard. It is
located in the ERMapper\batch directory. Run the script using
Batch Engine Script Control in the View menu.
Processing modules
The wizard consists of five main modules that you can access via the
main page:
Process TM imagery
Utilities and common algorithms used for processing TM image datasets.
Process Airphotos
Utilities and common algorithms used for processing Aerial Photographic
images.
Regolith Mapping
Utilities and common algorithms used for Regolith Mapping.
Floodzone Mapping
Utilities and common algorithms used for mapping flood zones.
Watershed Mapping
Utilities and common algorithms used for mapping watersheds.
Classifications
Utilities for classifying images.
Change Detection
Algorithms that highlight differences between images to facilitate change
detection.
Vector Creation
Utilities for creating vector layers on images.
The wizard is a productivity tool that addresses common Land
Applications processing requirements. As an example, the regolith
mapping utility contained within the wizard enables you to generate
images in a fraction of the time that it would take an interpreter to
produce manually with ER Mapper. The LAW incorporates three
techniques of Atmospheric Effect Correction, several techniques of
Change Detection, Automatic Surface Cover types extraction
together with other common algorithms used in Land Applications.
This wizard is intended for use by those who already have a good
knowledge of the processes involved. This description is limited to an
outline of the facilities included.
For information about training courses on the Land Applications
Wizard, please contact your nearest Earth Resource Mapping
office or reseller. Alternatively you can go to the
www.ermapper.com web site.
Some of the formulas and filters in the wizard use dynamic
compilation, and thus require you to have the Visual Studio 2005
compiler installed on your PC. Select the “Use Dynamic
Compilation” option from the Edit/Preferences/General
menu of the ER Mapper main menu window.
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ER Mapper Wizards
Refer to the “Land Applications Wizard” chapter in the
ER Mapper User Guide, for more information.
Landsat TM
Wizard
This wizard creates one of several standard Landsat TM algorithms.
You specify the Landsat TM image, and select the type of algorithm
required.
1. The Landsat TM wizard can be accessed from several toolbars -
Classification, Forestry, Minerals, Remote Sensing and
Wizards - by clicking on the Landsat TM Wizard
button.
The wizard opening page displays options to choose your dataset and
to choose from a range of algorithms that you would like to use to
process your image.
Landsat Web
Publishing Wizard
ER Mapper Wizards
This wizard simplifies the preparation of your Landsat 5 and 7 scenes
to be served from an Image Web Server, and creates ready-made
web pages for viewing the images from within a web browser.
Despite the large size of Landsat images, you can access them from
an Image Web Server very quickly - even over slow modem
connections. This is because the patented Image Web Server and
ECW technology use effective compression and two-way streaming
protocols to only send the imagery actually needed. The Landsat
Web Publishing Wizard simplifies the data preparation step.
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1. The Landsat Publishing Wizard
button can be found on the
Web Publishing toolbar of ER Mapper. If you don't have this toolbar
on your version of ER Mapper, you can download the wizard for free
from the ER Mapper web site:
http://www.ermapper.com
Preparing to use the
wizard
Before preparing Landsat images to be served over the web, you will
need:
•
The Image Web Server installed on a web site, to serve your
images.
•
One or more Landsat 5 or 7 images, ordered in ER Mapper or
multi-file GeoTIFF format.
•
A directory to store your prepared images and associated HTML
web files for users. This directory should be in the web server
directory path (or you can write files out to a local directory, and
then copy that directory over to your web server).
•
Sufficient disk space to store the compressed images. Assuming
you start with a full 9 band Landsat 7 scene, you will need about
100MB to store all compressed ECW images that can be derived
by this wizard from one original scene. Less disk space will be
required if you select to generate only some of the views.
1. Start the Landsat Publishing Wizard.
2. Follow the instructions on the wizard page, and navigate through
them by clicking on the Next>, <Back and Finish buttons. click on
the Cancel button to exit the wizard without any processing.
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ER Mapper Wizards
The wizard also conveniently “remembers” what you entered in a
previous session, so that you do not have to re-enter it if you are
using the same data.
This wizard processes imagery to create multiple views as required.
It can then optionally create ECW compressed files of the views and
store them in a directory for publishing via an Image Web Server. It
can also create ready-made Active Server Pages (ASPs) to enable
viewing from within client web browsers.
The input Landsat imagery can be either in the form of a single
ER Mapper Raster Dataset (.ers) file or multiple GeoTIFF/TIFF files.
The wizard performs the following operations for you:
•
Creates ER Mapper algorithms to read the original single or
multi-file Landsat 5 or 7 scene as a single logical image.
•
Creates multiple output ECW compressed view images from the
input scene. This is because most products need processed
resultant images to display, and can not create a view on the fly
as ER Mapper can. Your views might include simple displays of
the Landsat imagery, such as the common 542 RGB view, or they
might be processed results such as the NDVI vegetation index to
highlight vegetation, or the Oxide/Clay view for exploration
purposes. The wizard lets you select different ways to show the
Landsat imagery. Each of the ECW output files are written to the
web directory where the Image Web Server will serve the
imagery.
•
Some HTML web files can also optionally be copied to the output
directory, so your users can directly view the imagery from within
web browsers.
Refer to the “Landsat Web Publishing Wizard” chapter in the
ER Mapper User Guide for more information.
Local Council
Applications
Wizard
The ER Mapper Local Council Applications Wizard (LCAW) automates
a number of image processing procedures that could be used by local
councils (or other local government authorities).
1. To activate the wizard, click on the Local Council Applications
Wizard
button located on the Remote Sensing toolbar.
This will open the first page of the wizard.
If the toolbar is not visible, select it from the Toolbars menu list.
2. Follow the instructions on the pages and click the Next> button to
continue.
Available options
ER Mapper Wizards
The wizard main menu page displays the following options:
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Scanned map and airphoto (Pan)
integration
Integrates a scanned raster map with a Panchromatic
(single band) airphoto image.
Scanned map and airphoto (RGB)
integration
Integrates a scanned raster map with an RGB (3-band)
airphoto image.
Change Detection (Pan and Pan)
Highlights the differences between two Panchromatic
(single band) airphoto images to detect changes.
Change Detection (RGB and Pan)
Highlights the differences between an RGB (3-band) and a
Panchromatic (single band) airphoto image to detect
changes.
Change Detection (RGB and RGB)
Highlights the differences between two RGB (3-band)
airphoto images to detect changes.
Scanned map integration
The scanned map integration options allow you to specify an RGB or
Panchromatic airphoto image and a co-registered scanned raster
map. The wizard opens four image windows to display different
algorithms. It displays the photographic image and the scanned map
separately, and then uses two techniques to display the scanned
map draped transparently over the photographic image
Change detection
The change detection options allow you to select two Airphoto
images for the wizard to generate algorithms that highlight the
differences between them. This enables you to detect changes in the
landscape the have occurred between the times that an older or
newer image were taken.
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ER Mapper Wizards
The wizard displays the two images in separate windows, and one
image as transparent surface over the other in a third window. It also
opens three other windows displaying algorithms that highlight the
differences between the images.
This tool automatically runs change detection algorithms on
temporal aerial images. It also combines 1-Bit scanned mapping with
aerial images, changing line colors and removing white areas to aid
integration and visualization.
Refer to the “ Local Council Applications Wizard” chapter in
the ER Mapper User Guide for more information.
Magnetics Fourier
Wizard
This wizard provides you with an interactive method of applying a 1st
Vertical Derivative or Reduce to Pole Fast Fourier Transform formula
on a single band of an image.
1. The wizard can be opened by clicking on the Magnetics Fourier
Wizard
button on the Geophysics or Wizards toolbar
The Magnetics Fourier Wizard button is identical to the Fast
Fourier Transforms button on the Geophysics toolbar.
You specify the input and output image, and select the band and FFT
process to apply.
ER Mapper Wizards
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Map Collar Wizard
The Map Collar Wizard (previously the Map Topo/DRG Collar Clip
Wizard) creates a collar clip vector polygon region showing only map
contents. This wizard does not modify the map imagery. Once you
have run this wizard on maps, use the Image Display and Mosaic
Wizard to mosaic and clip the maps into a single seamless mosaic.
1. Start the wizard by clicking on the Define Clip Regions for
Topo/DRG maps
button on the Batch Processing toolbar.
The wizard can handle any image format supported by ER Mapper,
so you can use it for JPEG's, TIFF's, ERS files, ECW files, etc. If there
is no existing ERS file for the specified image, the wizard will create
one.
The following is a typical workflow procedure for creating a mosaic
of collared images:
Preparing the images
If you have a large number of images you want to collar, copy these
images into the same directory. There is also an option to collar
images within subdirectories of the directory you select.
The images do not have to be in the same format.
Running the wizard
This will open the first page of the wizard.
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ER Mapper Wizards
Read the wizard description and then select either the first option,
Collar one map to clip one map, or the second option Collar
multiple maps to clip all maps in a directory, optionally including
sub-directories.
2. After making your selection on the first wizard page, click Next> to
continue or Cancel to close the wizard.
The Map Collar Wizard automatically computes the collar clip regions
for maps such as USGS DRG topographic maps. The wizard
examines the overall extents of a mapsheet, works out the scale,
and computes the map content extents (the actual map information
inside the overall map page). A clip vector polygon region is then
added to the image header file (the image itself is left intact)
describing the collared region. The wizard also has built in batch
processing so that multiple mapsheets can be collared in a single
operation.
Starting with a collection of topographic maps (e.g., USGS DRGs),
the Map Collar Wizard allows you to create seamless mosaics of
entire states (or more!) at the press of a few buttons. The
combination of the Map Collar Wizard and the Image Display and
Mosaic Wizard deliver very powerful results, quickly and easily. No
more messing around trying to mask out the map collar "by hand" it is done automatically by the Map Collar Wizard!
Refer to the “Map Collar Wizard” chapter in the ER Mapper
User Guidefor more information.
MapInfo .tab File
Wizard
This tool reads existing MapInfo .tab files (image files only) and
automatically creates ER Mapper .ers header files. This allows
MapInfo users to view, mosaic and compress images with ER Mapper
without having to first manually convert them.
1. Click on the MapInfo .tab File Wizard
button in the
ER Mapper Reader toolbar to open the wizard and follow the
instructions.
The MapInfo .tab File Wizard creates .ers header files for all the .tab
files in the directory you specify that meet all the following criteria:
•
There must be an accompanying raster type image file.
•
The image must be in TIFF, BMP or JPEG format.
The MapInfo .tab File Wizard is a utility that extracts georeferencing
information from a MapInfo .tab header file and uses it to create an
ER Mapper (.ers) header files for the referenced TIFF (.tif) Windows
Bitmap (.bmp) or JPEG (.jpg) image data file.
ER Mapper Wizards
219
About .tab files
The table (.tab) file is a header file that is created by MapInfo to store
information on the coordinate system of the referenced image, and
the positions of objects on it.
A simple .tab file is shown below:
!table
!version 300
!charset WindowsLatin1
Definition Table
File "utm27.tif"
Type "RASTER"
(444642.8,4640515) (0,0) Label "Pt 1",
(451632.8,4640515) (698,0) Label "Pt 2",
(451632.8,4631225) (698,928) Label "Pt 3"
CoordSys Earth Projection 8, 62, "m", -87, 0, 0.9996,
500000, 0
Units "m"
The ‘Definition Table’ lines contain the information used by the
MapInfo .tab File Wizard, viz:
•
The name and type of the image file.
•
Pixel and the corresponding world coordinates of points on the
image. In the above example, these points are labeled “Pt 1”, “Pt
2” and “Pt 3”.
The MapInfo .tab File Wizard does not extract datum and projection
information from the .tab file, so you have to enter this.
Refer to the “MapInfo .tab File Wizard” chapter in the
ER Mapper User Guidefor more information.
Mineral
Exploration
Wizard (MEW)
This tool automatically processes, integrates, models and compares
Landsat TM images, and Radiometrics and Magnetics data with
specific routines necessary for the mineral exploration user.
Functions include Mapping Alteration Zones, Noise Reduction on
Radiometrics and Void Filling using FFT.
1. To activate the MEW, click on the Desktop Mineral Explorations
Wizard
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button located on the Geophysics toolbar.
ER Mapper Wizards
If the toolbar is not visible, select it from the Toolbars menu list.
2. Follow the instructions on the pages and click the Next> button to
continue.
The Display HSI wheel option opens an image window with an
RGB algorithm displaying an HSI Color Wheel. You can use this
to assist you in RGB and HSI color composite interpretation.
delete_windows.erb is a useful script for closing down the
multiple windows created by the Mineral Exploration wizard. It
is located in the ERMapper\batch directory. Run the script using
Batch Engine Script Control in the View menu.
Processing modules
The wizard consists of five main modules that you can access via the
main page:
Process TM imagery
Utilities and common algorithms used for processing TM
image datasets.
Process Radiometrics
Utilities and common algorithms used for processing
Radiometric image datasets.
Process Magnetics
Utilities and common algorithms used for processing
Magnetics datasets.
Data Integration and Comparison
Integrates different types of image data into a single virtual
dataset, which is then used in comparison utilities.
Model and display Target Areas
Models and displays target areas.
ER Mapper Wizards
221
The ER Mapper Mineral Exploration Wizard includes algorithm
processing, formulas, filters etc. that are commonly used in mineral
exploration. More than 40 separate batch routines are consolidated
in a single Wizard interface.
This wizard is intended for use by those who already have a good
knowledge of the processes involved. This description is limited to an
outline of the facilities included.
For information about training courses on the Mineral
Exploration Wizard, please contact your nearest Earth Resource
Mapping office or reseller. Alternatively you can go to the
www.ermapper.com web site.
Some of the formulas and filters in the wizard use dynamic
compilation, and thus require you to have the Visual Studio 2005
compiler installed on your PC. Select the "Use Dynamic
Compilation" option from the Edit/Preferences/General menu of
the ER Mapper main menu window.
Refer to the “Mineral Exploration Wizard” chapter in the
ER Mapper User Guide for more information.
Ortho and
Geocoding Wizard
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This wizard geocodes images (including orthorectification) to remove
distortion and set them to the correct spatial coordinates and
rotation.
ER Mapper Wizards
1. You can open the Ortho and Geocoding Wizard by clicking on the
Ortho and Geocoding Wizard
button in the Common
Functions toolbar. You can also access it by selecting Geocoding
Wizard from the Process menu.
2. Enter the file name of the image to be geocoded, and select the type
of geocoding required.
There are three buttons at the bottom of the dialog box, viz. Save,
Close and Cancel.
•
Save: Save the input header file containing georeferencing
details.
•
Close: Prompts you to save changes to the input header file
before closing the Ortho and Geocoding Wizard.
•
Cancel: Closes the Ortho and Geocoding Wizard without saving
any changes.
3. Select the Ortho and Geocoding Wizard tabs in numerical order, and
follow the instructions on each wizard page before continuing.
The Ortho and Geocoding Wizard will not allow you to continue to the
next page if you have not entered sufficient information.
4. The Ortho Setup tab for orthorectification requires you to enter the
file names of a DEM and a Camera File. If you do not have the
applicable Camera File, click on the Camera Wizard
button to
create one.
ER Mapper Wizards
223
You will need a Camera Calibration Report for information required
by the Camera Wizard.
5. On the final tab page, Rectify, enter the name of the file to which
the geocoded image is to be saved, and click on the Save File and
Start Rectification button to exit the wizard.
The orthorectification geocoding methods require a DEM. You
can use the Gridding Wizard to create a DEM from contour data.
See Gridding Wizard.
The Ortho and Geocoding Wizard will only process ER Mapper Raster
Dataset image files. If you have another image format (e.g.
GeoTIFF/TIFF or JPEG) to be geocoded, load it into an algorithm first
and then select Save As... from the file menu to save it as a Raster
Dataset (.ers) file.
The Ortho and Geocoding Wizard is an all-in-one tool for geocoding
images. The dialog box has a number of tabs which you select in
numerical order. The tabs change according to the type of geocoding
you select. The wizard also contains context sensitive explanatory
text fields.
ER Mapper’s Rectification utilities are commonly used to perform
four different types of operations:
•
Image to map rectification – using polynomial (control point) or
linear geocoding to rectify an image to a datum and map
projection using GCPs.
•
Image to image rectification – using polynomial (control point)
or linear geocoding to rectify one image to another using GCPs.
•
Map to map transformation – transforming a rectified image from
•
Image rotation – rotating an image any number of degrees.
one datum/map projection to another.
To use Orthorectification you must have the following information
available:
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•
Camera file containing camera calibration information
•
DEM file (You can enter an average height if the terrain is
relatively flat)
•
Exterior orientation (Only for Advanced Orthorectification.
Otherwise you must select GCPs)
•
GCPs referenced by their XYZ coordinates.
ER Mapper Wizards
Limitation of Ortho and Geocoding Wizard - Windows allows
processes to realize a 32-bit linear address space for 4GB of
memory. However, only the lower 2GB of this private address
space can be utilized by the process as the system reserves the
upper 2 GB of every process's address space for its own use.
As the rectification input and output must be loaded into one
contiguous chunk of virtual memory, their combined size cannot
exceed this 2GB process limit.
If you have a related problem when geocoding your images,
please contact [email protected] for a work-around.
For further details about geocoding and orthorectification refer
to the “About Geocoding” and “Orthorectification” chapters
in the ER Mapper User Guide. Worked hands-on exercises with
example datasets using the Ortho and Geocoding Wizard are
also given in the online ER Mapper Tutorials “Image
geocoding” and “Image orthorectification”.
Page Setup
Wizard
When an algorithm is created it is assumed that eventually it may be
printed out to a physical media or a ‘page’. Algorithms have a ‘page
size’ associated with them to help you compose the printed output,
including images for reports and professional quality maps.
1. To access the Page Setup wizard, either select Page Setup Wizard
from the File menu or click on the Page Setup Wizard
button in the Annotation or Wizards toolbar.
ER Mapper Wizards
225
Follow the instructions in the Page Setup wizard.
The wizard interactively leads you through setting up a page,
including the addition of an optional vector layer and provides
explanatory text. It is a tool to help you create top quality
cartographic image maps. Use the wizard to set up a page size and
extents for your map.
The ‘page size’ is used to determine the way in which vector objects
are displayed, for instance line thickness or text height; it also lets
you control the borders and scale of the output. The size of a vector
object is set relative to the ‘page’, this means that 12 point text will
appear a different size on the screen if the algorithm has page sizes
of A4 or A0.
You can use Page Setup to:
•
define the algorithm page size and background color defaults
used by hardcopy
•
set the default hardcopy device
•
specify image borders on a page
•
set the scale of the algorithm.
•
set the extents of the algorithm to be printed.
To learn more about setting up your page and for a hands-on
exercise refer to the “Page Setup” and “Composing maps”
chapters in the ER Mapper User Guide
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ER Mapper Wizards
Other wizards
This sections provides information regardsing some of the other
wizards available for you to use.
HGT Batch Import Wizard
This wizard can be used for the import of Shuttle Radar Topography
Mission (SRTM) DEM data in HGT format.
SRTM DEM files are stored in a BIL-like format called HGT. Most data
is 3-arcseconds per value, while some is of higher resolution (1arcsecond over the USA). You will need to specify the correct
arcseconds when using the HGT Batch Import Wizard.
1. Click on the HGT Batch Import Wizard
button in the Batch
Processing toolbar. The wizard creates .ers files to directly point to
and read HGT format images.
This wizard will overwrite any existing ERS files present for the
HGT DEM files.
Image subset Wizard
This wizard is used to save a subset of an existing image.
1. To access this wizard, select Utilities>File
Maintenance>Dataset> Save a subset of an image.
Machine Configuration
Report Wizard
This wizard will check your computer’s configuration for compatibility
with ER Mapper and may recommend changes to improve
performance (it will not actually make any changes).
1. To start this wizard, select Utilities>Machine Configuration
Report.
The opening page of the wizard will appear. Click Next> and continue
to be presented with configuration details and recommended actions
for various sub-systems of your computer.
You can save the report to a text file. Use this file when reporting
problems or defects to Earth Resource Mapping.
Large Mosaic Wizard
Managing large algorithms
If you are saving an ER Mapper algorithm as a compressed image,
you can minimize the resultant file size by turning off or deleting
algorithm layers that fall outside the image window extents. Some
algorithms contain thousands of mosaiced images, which makes it
difficult to manually detect layers that fall outside the window
extents.
The Large Mosaic Wizard will do this for you quickly and easily.
1. To use the wizard, load the algorithm into an image window and click
on the Manage large algorithms button
ER Mapper Wizards
.
227
If the button is not available on the Compression toolbar, you
will find it on the Batch Processing toolbar.
2. Select the required option and click on the Next button.
Turn on all raster layers
The wizard looks for any algorithm layers that have been turned
off, and turns them on. This is a way of checking that all the
algorithm information is included before creating a compressed
image.
Turn off images outside window The wizard looks for any images in the mosaic that fall outside
extents
the current window extents, and turns them off.
The wizard will display the number of layers that were turned off.
Delete all layers turned off
The wizard looks for any algorithm layers that have been turned
off, and deletes them.
3. When the wizard has executed your request you can click on the
Finish button retain the changes, or the Cancel button to revert to
algorithm to what it was previously.
In a typical scenario, you might open an algorithm, turn an all the
raster layers, turn off images outside the window extents and then
delete the layers that were turned off.
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ER Mapper Wizards
For more information on image compression, please refer to the
online ER Mapper User Guide “Compressing images”.
Using batch scripts and
designing your own
wizards
You can use the ER Mapper batch scripting language to design your
own wizards to simplify regular tasks. You can even add an entry or
button to the menu and toolbars.
Refer to “Batch Scripting and Wizards” in the online
Customizing ER Mapper manual for information on the batch
scripting language.
ER Mapper Wizards
229
230
ER Mapper Wizards
Classification
Supervised
classification
Supervised classification uses existing region or class statistics to
label each cell in an image as belonging to a particular class. The
statistics are drawn from training regions which can be created in a
number of ways. For example, they may be drawn by hand, or be
converted from a vector image, using the Annotation System, or
they could be output from the Unsupervised Classification utility (or
even a previous supervised classification run).
To carry out a supervised
classification:
1. Start with an unclassified image.
2. Make sure statistics have been calculated for the image. Use the
Calculate Statistics option from the Process menu (all images
contain the region “All”).
3. Obtain region or class means to be used for the classification. These
may be:
•
polygon training regions drawn using the Annotation system
•
classes output from the Unsupervised Classification program (or
previous supervised classification run)
•
polygon regions converted from a vector polygon image using
the Annotation tool.
4. Specify and perform the classification using the Classification /
Supervised Classification option on the Process menu.
5. From the Process / Classification menu, select the Edit
Class/Region Color and Name... option to assign label and colors
if necessary.
6. Display the regions by adding a Classification Display layer to the
algorithm.
In the Supervised Classification window you must specify:
Classification
•
The INPUT Dataset: this is the unclassified image
•
The OUTPUT Dataset: this is a new image with a class band
whose value at each cell is the class of that cell. Other bands with
post probability and typicality can be requested.
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•
The training regions: you can use regions from any number of
images at the one time, selecting classes individually from the
source images
•
training region labels and colors are preserved
The statistics calculated by the supervised classification program can
be viewed using the View / Statistics menu options.
Unsupervised
Classification
Classification is the process of identifying clusters of similar data in
an image, such as different crops, different minerals or urban and
rural areas. ER Mapper’s Unsupervised Classification utility will take
unclassified images and generate a classified image consisting of a
single band, byte image, with each data point holding an integer
value which is the class number for that point.
To carry out
unsupervised
classification
1. From the Process menu, select the Classification / ISOCLASS
Unsupervised Classification option to open the Unsupervised
Classification window.
2. Select the Input and Output datasets and Bands to use (default
is ALL). Run it with the default processing control parameters or edit
them as desired.
3. If the classes become stable, processing stops even if the specified
number of iterations has not been reached. Speed up the processing
time by subsampling the image (because of the data format,
specifying a Sampling row interval is faster than a Column).
Selecting Auto Resampling means ER Mapper will automatically
reduce the sampling interval as the classes stabilize. Regardless of
the subsample factor specified, ER Mapper always classifies the
entire image in the final pass.
To display the classified
data
1. From the Process / Classification menu, select the Edit
Class/Region Color and Name option.
2. Load the classified image: classes are listed, showing “unlabeled”
and “black”.
3. Choose Auto-gen colors... to assign colors to the classes
automatically, simulating an RGB image, or set the colors
individually using the Set color... buttons. Class colors and labels
can be edited at any time.
4. Add a Classification Display layer to your algorithm in the Algorithm
window and load the image.
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Classification
Before you perform Unsupervised Classification on an image you
must already have calculated statistics for the entire image.
If you specify a classified image in the Use classes field, ER Mapper
will use the cluster centers from that image and use them as a
starting point for the new calculations. If you specify the same image
in the Use classes and Output Dataset fields, the class centers will
be read before the image is overwritten.
The statistics can be viewed using the Statistics menu options on
the View menu.
Refer to “Regions and Statistics”, and “Classifying images”
in the ER Mapper User Guide for more information.
Classification
233
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Classification
Dynamic Links
ER Mapper Dynamic Links allow integration of data from many
sources with Raster and Vector data.
Not to be confused with Import programs, Dynamic Links directly
extract information from the link source (such as ARC/INFO or
Oracle), every time an image is generated. This allows interactive
generation of images based on data in external systems.
Dynamic Links appear as ER Mapper Algorithm Layers, and may be
accessed via the Edit menu in the Algorithm dialog box. For
example, one Dynamic Link layer in an algorithm might extract a
vector layer from ARC/INFO while a second might extract tabular
information from Oracle and show it in a graphic form.
All Dynamic Links return data in a PostScript format, allowing
Dynamic Links to be created for a wide variety of sources.
To add a Dynamic Link
layer to an algorithm
1. Use the Edit / Add Vector Layer menu in the Algorithm window
to select the desired Dynamic Link. Dynamic Link options are in the
lower part of the menu. There are links to such things as GIS
systems and external vector formats.
2. Use the Dataset or Dynamic Link Chooser buttons to select the
data source.
3. Set the default layer color using the Edit Layer Color button.
ER Mapper users can add new Dynamic Links to specialized
systems at any time by adding new entries in the
“config\dynamiclinks.erm” configuration file and including the
PostScript generation programs in the “bin” directory. The
Dynamic Link file formats are fully documented in the
Customizing ER Mapper manual. Once a link has been added, it
is accessed via the ER Mapper Graphical User Interface from
within the Algorithm dialog box.
Dynamic Links are triggered whenever an image is updated (for
example, due to a Zoom) or during printing.
Dynamic Links only request data for the area currently covered by
the algorithm generating the image.
A number of Dynamic Links are provided with ER Mapper. Some of
these links will only operate if you have licenses for the appropriate
systems.
Dynamic Links
235
For more information, refer to “Dynamic Links (vector
layers)” in the ER Mapper User Guide and “Dynamic Links
menu” in the Customizing ER Mapper manual
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Dynamic Links
Fourier processing
ER Mapper supports frequency domain processing using forward and
reverse Fourier transformations.
To transform an image to
or from the frequency
domain
1. From the Process menu, select Fourier Transformations...
Alternatively, select the Fast Fourier Transforms button
from
the Geophysics toolbar.
2. Choose your input image.
If you choose a transformed image the header changes to read ‘FFT
- Reverse Transformation’ and the processing options, except “Don’t
Replace NULLs” are grayed out.
3. Choose the output image.
For a transformed image, select matching pairs of real and imaginary
bands.
4. Specify processing options as required.
5. Select Full Spectrum to create a full spectrum image. By default
Full Spectrum is not selected and a half spectrum image will be
created.
Reduced Precision. By default ER Mapper processes all images
using Double Precision numbers. This can considerably increase the
size of your Work Area and Output file. Select Reduced Precision
to use float IEEE4 instead of IEEE8 numbers.
Padding is always added as required for the Fast Fourier processing
algorithm. When Prevent Wrapping is selected the padding is not
filled so edge effects are present.
If you are reverse processing a transformed data set, select Don’t
Replace NULLs if you do not want to restore areas of NULLs from
the Input Image.
The Magnetics Fourier Wizard provides you with an interactive
method of applying a 1st Vertical Derivative or Reduce to Pole
Fast Fourier Transform to an image. Click on the Magnetics
Fourier Wizard button
on the Geophysics toolbar to
activate it.
Fourier processing
237
To apply a filter
The filters for FFT processing are carried out using usercode
functions - external C functions accessed by ER Mapper. Example
algorithms demonstrating high and low pass filters and notch filters
can be found in the ‘examples\Functions_And_Features\Fft’
directory. Example formulae can be found in the formula\fourier
directory.
1. From the File menu, select Open and load the appropriate filter
algorithm.
2. From the View menu, select Algorithm... to open the Algorithm
dialog box.
3. In the Algorithm dialog box click on the Edit Formula button
to open the Formula Editor.
4. Edit the function parameters to give the results you want.
Refer to “Fast Fourier Transforms” in the ER Mapper User
Guide and “Fast Fourier Transforms” in the ER Mapper
Applications Manual.
238
Fourier processing
Geolinking
Geolink (Screen,
Window or None)
ER Mapper can link windows together or to the screen.
Geolink a window using the Geoposition Window option on the
View menu. The choices for the Geolink option are: None,
Windows, Screen, Overview Zoom, and Overview Roam. Overview
Zoom and Roam are described in the next topic.
None
This is the default option. Windows are independent of each other
and the screen.
Windows
Select this option in each of a number of windows that you wish to
tie together (the extents of the first linked window are used). All
linked windows in the same coordinate space will have the same
zoom extents. A zoom in one window triggers a zoom in the other
linked windows.
Screen
All windows in the same coordinate space share the map extents
across the screen (in other words, each window will have different
but related extents). The shared coordinate space is defined by the
first linked window.
Moving a window triggers a redraw in that window only, whereas
zooming in a window triggers a zoom in all related windows (in the
same coordinate space).
If you resize a window, you will see more or less of the image, you
will not trigger a zoom. To zoom use the Geoposition dialog box
Zoom options.
To Geolink windows
•
From the View menu, select Geoposition to open the
Algorithm Geoposition Extents window and click on the
Geolink tab to view and edit the Geolinking parameters.
•
For each window you want to link, click on the window to make
it the active window, click on the Geolink mode to select it and
then press Apply.
Geolink modes can also be set using the View / Quick Zoom
menu.You can also access the Quick Zoom menu by rightclicking anywhere on the image with the cursor set to Zoom
mode.
You can have windows in different Geolink modes.
You can geolink a single window to Screen: when you move the
window a different part of the image is shown.
Geolinking
239
Geolink
(Overview Zoom
and Roam)
ER Mapper can link windows together or to the screen.
Geolink a window using the Geoposition Window option on the
View menu. The choices for the Geolink option are: None,
Windows, Screen, Overview Zoom, and Overview Roam. The last two
are described in this topic; None, Windows and Screen are described
in the previous topic.
Overview enables you to link two or more windows together. Unlike
Window geolinking, Overview Zoom and Overview Roam only
affect other image windows in the same coordinate space.
Overview Zoom
Zooming in the Overview window zooms all the other windows set to
Geolink - None. For example you may have a large window with a
complete overview Landsat image, and several images zoomed in on
a selected detail.
Roam
Overview Roam centers the other images over a selected
coordinate; the scale is not changed. Hold the left mouse down to
continually update the other windows as you track the mouse. Before
using Roam you may wish to set the zoom.
To Geolink windows
1. From the View menu, select Geoposition to open the Algorithm
Geoposition Extents window and click on the Geolink option at the
top of the window to view and edit the Geolinking parameters.
2. For each window you want to link, click on the window to make it the
active window, click on the Geolink mode to select it and then press
Apply.
Geolink modes can also be set using the View / Quick Zoom
menu. You can also access the Quick Zoom menu by rightclicking anywhere on the image with the cursor set to Zoom
mode.
When loading an algorithm into a window geolinked to Windows or
Screen, the loaded algorithm inherits the zoom extents of the link,
rather than using the extents in the loaded algorithm. To use the
extents in the loaded algorithm, set Geolink mode to None.
Zooming changes the scale of the image, not the size of the window.
Refer to “Geopositioning and zooming” in the ER Mapper
User Guide.
240
Geolinking
Importing/Exporting raster and vector
images
ER Mapper Import and Export utilities translate images in many
different raster and vector data formats to and from ER Mapper
raster and vector files.
For example, you can import an image in an external file format,
display and enhance it and then export it again.
Import and export programs can be selected from the Utilities
menu and have a common interface.
Importing
1. From the Import options on the Utilities menu, select the
appropriate import program.
2. In the import window, fill in the Input File / Device Name and
select the Output Dataset name from a menu. Edit the other fields
as required (you can specify to import only part of an image). The
Map Projection details (Geodetic Datum, Map Projection and
Rotation) may need to be specified.
Exporting
1. From the Export options on the Utilities menu, select the
appropriate export program.
2. Select the ER Mapper image to export and press OK to begin.
Import and export utilities can also be run using a command line
equivalent, which is useful if you are converting a large number
of data files. This is detailed in the Customizing ER Mapper
manual.
Importing/Exporting raster and vector images
241
You can load and save images directly from and into the following
formats without having to import or export them.
Load
Save
ER Mapper Algorithm (.alg)
ER Mapper Algorithm (.alg)
ER Mapper Raster Dataset (.ers)
ER Mapper Raster Dataset (.ers)
ER Mapper compressed (.ecw)
ER Mapper virtual dataset (.ers)
Vector Map (.erv)
ER Mapper compressed (.ecw)
ESRI BIL and GeoSPOT (.hdr)
Windows BMP (.bmp)
Windows BMP (.bmp)
ESRI BIL and GeoSPOT (.hdr)
GeoTIFF/TIFF (.tif/.tiff)
GeoTIFF/TIFF (.tif/.tiff)
JPEG (.jpg)
JPEG (.jpg)
JPEG 2000 (.jp2, .jpx, .jpf, .j2k, .j2c and .jpc )
JPEG 2000 (.jp2)
NITF (.ntf)
NITF (.ntf)
USGS DOQQ grayscale (.doq)
UDF (.ers and .hdr)
RESTEC/NASDA CEOS (.dat)
Landsat 7 FastL7A (.fst)
Aster/MODIS/Landsat7/EODIS/SPOT vegetation
(.l1g, .l1r, .met, .hdf)
Refer to the following for more information: “Importing and
exporting data”, “Saving images”, “Supported import
formats”, “Supported export formats” in the ER Mapper
User Guide and “Importing using a command line” in the
Customizing ER Mapper manual.
242
Importing/Exporting raster and vector images
Map projections supported by ER Mapper
This chapter lists the projections supported by ER Mapper and the
GDT database files associated with each.
For complete details on how ER Mapper handles datums and
projections, refer to Positioning your Image Geographically
(Geocoding), in the “Introduction to Map Projections” of the
ER Mapper User Guide.
Datum definition
files
One file is used by the GDT routines to obtain datum parameters.
This file is datum_sp.dat. This contains the name of the datum, the
radius and the eccentricity. The file also contains the meter factor
used for easting/northings - this is usually 1.0 for datums where the
“natural” unit is the meter, or 0.304800609660 for datums where
the “natural” unit is the foot
Information used when changing from one datum to another is
stored in file datumcha.dat. (This file contains the translation and
rotation (Bursawol) parameters for moving the datums in space).
Currently the only supported datum change type is “bursawol”,
which tells the software to look in file bursawol.dat to get the
datum change parameters.
The descriptive information describing the spheroid and tie point that
you see in a datum scrolling chooser in ER Mapper is obtained from
file datum.dat. This file lists every datum supported by ER Mapper
Supplied
projections and
projection
definition files
In addition to the primary projection file project.dat, each
projection type has its own projection definition file in which the
particular parameters for each projection of that type are defined. To
add a new projection to ER Mapper you must add a new entry for the
projection to both the project.dat file and the projection definition
file (see “Adding a new projection to ER Mapper” in the
ER Mapper User Guide). A list of each projection type and its
corresponding projection definition file is given below.
•
albersea.dat: Albers Equal Area
•
azimuted.dat: Azimuthal Equidistant
•
bioconco.dat: Bipolar Oblique Conic Conformal
•
bonne.dat: Bonne for North America
•
borneo.dat: Rectified Skew Orthomorphic
•
cassini.dat: Cassini-Soldner
•
coniced.dat: Conic Equidistant
Map projections supported by ER Mapper
243
•
danish_uts.dat: Danish Universal Transverse Mercator
•
dutch.dat: Stereographic (oblique)
•
gnomonic.dat: Gnomonic Projection
•
grinten.dat: Van Der Grinten’s Projection (Sphere)
•
labordom.dat: Laborde Oblique Mercator
•
lambazea.dat: Lambert Azimuthal Equal-Area
•
lambert1.dat: Lambert Conformal Conic with One Standard
Parallel
•
lambert2.dat: Lambert Conformal Conic with Two Standard
Parallels
•
lamcon2.dat: Lambert Conformal Conic with Two Standard
Parallels1
•
mercator.dat: Mercator Projection
•
millercy.dat: Miller Cylindrical
1. lambert2 and lamcon2 are both Lambert Conformal Conic projections with two
standard parallels (LCC). lambert2 was the original LCC, and its equations are based
on "Survey Computations 2nd Edition 1932 - HMSO" (HMSO - His Majesty's Survey
Office). However, this projection has problems with convergence and
<false_northing> and <center_lat> parameters. As a result lamcon2 was introduced
just prior to Release 4.1. Its equations are from "Map Projections - A Working Manual",
by John Snyder.
The lambert2 projection type has been removed from ER Mapper's GDT database. All
of the lambert 2 projection types have been moved to the lamcon2 projection type.
* All projection definitions from lambert2.dat have been moved to lamcon2.dat.
* All occurrences of lambert2 have been changed to lamcon2 in project.dat.
* All occurrences of lambert2 have been changed to lamcon2 in projinst.dat.
* All occurrences of 01_lambert2, 02_lambert2 and 03_lambert2 have been changed
to 01_lamcon2 in projinst.dat.
* 01_lambert2, 02_lambert2 and 03_lambert2 have been removed from projdesc.dat.
* lambert2.dat has been removed from the GDT_DATA directory.
Note: The ER Mapper installer gives users the option to make a backup of their
GDT_DATA directory. If you have custom projections in lambert2.dat, then select
'yes' to the GDT_DATA backup during install and then copy your custom lambert2 projections from the lambert2.dat file in their GDT_DATA backup directory to the
lamcon2.dat file.
Earth Resource Mapping encourages users adding their own definitions to the GDT Database to submit these to us so we can add them to the GDT library in future releases
of ER Mapper.
244
Map projections supported by ER Mapper
•
modpol.dat: Modified Polyconic
•
modstero.dat: Miller Stereographic (Sphere)
•
mollweid.dat: Mollweide Projection
•
obmerc_b.dat: Hotine Oblique Mercator
•
obmerc_c.dat: Rectified Oblique Mercator
•
orthog.dat: Orthographic Projection
•
regpol.dat: Regular Polyconic
•
robinson.dat: Robinson Pseudocylindrical
•
sinusoid.dat: Sinusoidal Projection
•
stereo.dat: Polar Stereographic
•
stm.dat: Southern Transverse Mercator
•
swiss.dat: Swiss Cylindrical
•
tranmerc.dat: Transverse Mercator
•
utm.dat: Universal Transverse Mercator
Map projections supported by ER Mapper
245
246
Map projections supported by ER Mapper
Printing
The ER Mapper Hardcopy engine can generate hardcopy output on a
wide range of output devices, including color printers, film writers,
black and white printers and other raw devices. You can produce
hardcopy output from any algorithm. The output scale or size can be
specified. Hardcopy images larger than the physical device will
automatically be cut into strips or pages, and output. PC users are
advised to use the Windows native hardcopy drivers supplied with
their systems.
To produce a hardcopy
image
1. From the File menu, select Print.
2. Select either PC Printing or Hardcopy Control Files.
3. Select the algorithm. (The algorithm in the active window is
automatically chosen).
4. Select the hardcopy Output Name if you selected Hardcopy
Control Files and it is different from the default.
5. Press Setup to edit the hardcopy device parameters if necessary.
6. Specify the size of the output either as a Width, in millimeters or
inches, or using Scale. The default is the defined page width
supported by the device.
If the hardcopy is larger than the physical device the hardcopy
program will automatically cut it up into strips or pages as
required.
Hardcopy devices are controlled by either their Windows drivers or
Hardcopy “.hc” entries; full details are in the Open Standards
manual.
Directly supported devices are listed in “Supported Hardcopy
formats and devices” of the ER Mapper User Guide.
Print setup
Printing
Before printing an image, you can check the Print Setup dialog box.
This sets information such as the background color, page orientation
and any gamma correction your printer requires.
247
If you select Hardcopy Control Files in the Print dialog box, then
the information in this dialog box comes from the hardcopy control
file selected in the Output Name field in the Print dialog box, or
from the Page Setup window. If you selected PC Printing in the
Print dialog box, then the print setup is done via the Windows Print
Setup dialog box that is applicable to the printing device.
To edit print settings
(Hardcopy Control Files)
1. From the File menu, select Print. The Print dialog box is displayed.
2. Select Hardcopy Control Files.
3. Choose the hardcopy control file applicable to your printer in the
Output Name field.
4. Click on Setup.... The Print Setup dialog box is displayed. This
includes the following fields:
The hardcopy device Description. This also appears in the
Description field in the Print dialog box.
The Background Color of the image. Set color... displays a Color
chooser so you can change the background color.
Select From Algorithm to use the background color from the
algorithm. The RGB values are displayed in the Background Color
field.
You can use Gamma Correction to adjust the components of a
printed image to compensate for the color bias of your printer. View
Colors displays the results of your color adjustments as you
manipulate the gamma correction sliders. Reset Gamma resets the
colors to the values stored in the hardcopy control file.
DPI is the hardcopy device image resolution in Dots Per Inch.
Page (Strip) is the output page width in dots.
The Filter program converts the output from ER Mapper to the
format required by your printer.
The Output Program sends the output from the filter program to a
file on disk, to tape, or direct to your printer.
You can Force 1 dataset cell to equal 1 image pixel to prevent
subsampling. Useful when creating graphics image files in a different
format with the same resolution data.
Force 1 Single Page to force the image to one page; usually used
to print to a file.
Orientation select either portrait (the default) or landscape.
To edit print settings (PC
Printing)
1. From the File menu, select Print. The Print dialog box is displayed.
2. Select PC Printing.
248
Printing
3. Select the printer in the Output Name field.
4. The Windows Print Setup dialog will appear for you select a printer
and change its properties if necessary.
5. Click on Setup.... The Setup Native dialog box is displayed.
6. You can choose a background color or select that set in the algorithm
page setup.
7. Click on Close to go back to the ER Mapper Print dialog, or Print
Setup... to open the Windows Print Setup dialog.
Any changes will affect the current print. You can also save the
new settings to the original file or create a new hardcopy control
file.
Refer to “Printing” and “Supported Hardcopy formats and
devices” in the ER Mapper User Guide and “Hardcopy files
(.hc)” and “Hardcopy Processing and Filter programs” in
the Customizing ER Mapper manual.
Printing
249
250
Printing
Virtual datasets
Algorithms can be treated as Virtual Datasets, which look and
behave like real image datasets except that the data is computed on
demand. This sort of image is usually used to look at images in a
number of different ways. There are a number of reasons to use
virtual datasets.
Reduce the data complexity. Layers that are made up of a
combination of bands of data, for example, vegetation indexes in
Landsat TM images, become a single band of data in the virtual
dataset and so are more easily manipulated.
Reduce disk storage. Virtual datasets are computed on demand so
no disk storage is required for intermediate image storage.
Mosaic a number of images together to produce one large
image. Load the images into separate layers, make sure all the
layers have the same description and Save Algorithm As Virtual
Dataset... All the images will look like a single image and can be
enhanced together.
Look at a portion of a large image or several mosaiced
images. Use the Geoposition window to set the window extents of a
number of virtual datasets, producing a number of map sheets.
Create new types of data. For example, a 10 meter, 7 band,
virtual dataset as a combination of Landsat TM and SPOT Pan.
To create a virtual
dataset
1. Use the Algorithm window to create the algorithm you want. You
might find it easier to start by using the File / Open... command to
load an existing algorithm from the ‘Virtual_Templates’ directory and
changing the image and any other relevant parameters.
2. In the layer list, type identical descriptions into the first (description)
field of each of the layers you want to combine.
3. From the File menu, select Save As.... Select the ER Mapper Virtual
Dataset file type and specify a new image name in one of the image
directories. Layers with different names or types will be saved into
different bands in the virtual dataset.
4. Answer Yes (recommended) or No to deleting the output transforms
before saving.
To use a virtual dataset:
1. Open a new window and use the Load Dataset button. In the Raster
Dataset chooser dialog, select ER Mapper Raster Dataset in the
Files of Type field. Alternatively select Open from Virtual
Dataset... from the File menu.
Virtual datasets
251
2. Use the Band selector to select the view you want. Use the Edit
Formula button to combine the views represented by the individual
bands. Use the Edit Transform Limits button to enhance the entire
virtual dataset.
You will usually want to delete all output transforms when saving
the virtual dataset so the data is not scaled. ER Mapper will
prompt you to do so.
Refer to “Virtual Datasets” and “Saving images” in the
ER Mapper User Guide for more information on virtual datasets.
252
Virtual datasets
ER Mapper documentation
Introduction
Apart from this Using ER Mapper print manual, all the ER Mapper
manuals are available in online help format featuring extensive
context-sensitive lookup, index and contents facilities. The online
help manuals have up-to-date information on the latest features and
developments.
The following online help manuals can be accessed from the
ER Mapper menu bar (click on Help and select the required manual
from the drop-down list):
•
ER Mapper Release Notes
•
ER Mapper Airphoto Tutorial
•
ER Mapper Applications
•
Customizing ER Mapper
•
ER Mapper Configuration
•
ER Mapper Tutorial
•
ER Mapper User Guide
This Using ER Mapper print manual is a condensed version of these
online manuals.
ER Mapper Release Notes
Use these release notes when you need specific information about
changes introduced in the latest release of ER Mapper. You will also
find sections listing the enhancements in ER Mapper since version
6.0 was released included in this document.
If you are familiar with previous versions of ER Mapper make sure
you read the latest release notes as it lists the major changes and
new features of the release that you are about to install. It will help
you make the transition to the new look and feel of the new release.
If you are new to ER Mapper, or are upgrading from an earlier
version of ER Mapper, the release notes will give you an idea of the
new features that have been added, and the problems that have
been fixed.
ER Mapper Airphoto
Tutorial
This manual is intended to get you started with using ER Mapper to
create mosaics of digital aerial photographs. It provides simple stepby-step procedures that give you hands-on practice using advanced
features of the software.
This manual is not intended to cover all ER Mapper functionality, and
does not cover concepts of digital photogrammetry such as DEM
generation.
ER Mapper documentation
253
Please refer to the ER Mapper Tutorial and User Guide
manuals for more detailed information as needed (These are
also accessible directly from the online help system).
Topics include orthorectification, map-to-map reprojection,
mosaicing, color balancing, ECW compression and the use of plugins to open ER Mapper images in GIS and Microsoft Office
applications
The chapters in this manual give you extensive hands-on experience
using the ER Mapper software through a series of specially designed
lessons. Most lessons have two basic sections:
•
an overview of key concepts
•
a series of step-by-step hands-on exercises
The emphasis of this manual is on learning and using the ER Mapper
software, not on teaching image processing, airphoto interpretation,
and other concepts.
ER Mapper Applications
This manual provides studies and tips on using ER Mapper for
different applications, and a list of the algorithms, filters and lookup
tables supplied with ER Mapper
The purpose of this manual is to show you examples of ER Mapper
at work. It attempts to go deeper than the other manuals in the set,
discussing the application of general concepts to particular
circumstances. The topics have been grouped roughly into parts for
convenience but the chapters are by no means exclusive. The aim
has been to go for breadth of coverage rather than duplication. By
the nature of the product and disciplines in which it is used, some
techniques will apply to many applications. You may want to
approach the manual by reading the chapters most relevant to your
application and then skimming the headings in the other chapters to
see if they discuss other techniques you are interested in. You may
also want to use the index to find references to particular
applications or techniques.
The Applications manual broadly divided into the following parts:
254
•
ER Mapper Applications
•
Case Studies
•
Oil and Gas
•
Supplied Processing
ER Mapper documentation
This manual assumes that you already know your way around
ER Mapper - for example how to change histograms or add filters. If
not, you will have to look these techniques up in the User Guide or
ER Mapper Tutorial. For example, the User Guide will describe how
to add a filter while this manual will suggest which filter to use in a
particular instance.
If you haven’t used ER Mapper before you may still want to browse
through this manual to get an idea of the diverse ways in which the
product can be used.
Customizing ER Mapper
The Customizing manual gives detailed information on how to
customize ER Mapper to suit your use and application. Topics
covered in this manual include using the scripting language to
develop your own macros and wizards to automate your custom
tasks, linking to ER Mapper, changing and adding tools to the
interface and the standards and file formats that ER Mapper uses.
The information in this manual is meant for advanced users,
developers and for troubleshooting.
The topics are grouped under the following sections:
•
Information for C/C++ Programmers
•
Open Standards
•
File Formats
•
Processing and Configuration Files
•
Interfaces and Utilities
•
Batch Scripting and Wizards
•
Appendices
ER Mapper Installation
The ERDAS IMAGINE Configuration Guide for Windows covers the
basic installation and licensing topics which are covered in this
printed manual as well as some advanced configuration,
environment variable and printing issues. For details on the
installation and configuration of digitizers with ER Mapper, see the
ER Mapper Configuration Guide.
ER Mapper Tutorial
The ER Mapper Tutorial is an extension of the tutorial presented in
this manual and covers advanced topics such as colordraping, HSI
algorithms, geolinking images, virtual datasets, thematic raster
overlays, Unsupervised and supervised classification, gridding,
geocoding and otrhorectification.
ER Mapper documentation
255
The tutorial is presented in the form of easy-to-use hands-on
exercises with an overview of key concepts. Sample datasets are
provided with ER Mapper. If you are new to ER Mapper, it is
recommended that you start at the beginning and proceed through
the chapters in order because the later chapters build on concepts
learned in earlier ones. However, each chapter is independent of the
others, so you can refer to a specific chapter at any time for a quick
procedural overview or refresher course.
The emphasis of this manual is on learning and using the ER Mapper
software, not on teaching remote sensing concepts and applications.
For more detailed information on the principles of image processing
or remote sensing for specific applications, please refer to the
ER Mapper Applications manual, or any of the text books available
(some examples are listed in "Reference texts" in the online Tutorial
manual)
ER Mapper User Guide
The User Guide provides in-depth information about ER Mapper
options and capabilities.
Use the User Guide when you need specific information about the
ER Mapper software. You’ll also find tips that provide you with
additional information about using many of the commands.
In addition to this, the manual gives background technical
information on various complex topics like gridding, geocoding, map
projections and orthorectification.
256
ER Mapper documentation
Index
Symbols
.bmp 14
.dat 14
.doq 14
.ecw 14
.ers 14
.fst 14
.hdf 14
.hdr 14
.jgw 14
.jpg 14
.tif/.tiff 14
Numerics
3-D Algorithm Wizard 187, 193
3D perspective viewing 48
A
About mosaics 103
Albers Equal Area map projection 243
Algorithm dialog
overview 37
Algorithm Geoposition Extents dialog box
Zoom options 32
algorithm layers. See layers
algorithms
basic concepts 12, 37
changing bands 41
changing lookup table 42
commenting 47
creating automatically 184
creating manually 183
entering description 45
extents 226
formula button 186
mosaics 104, 111, 115, 120
opening 29
page size 225
printing 153
process diagram 39
saving 45
simple example 43
stopping (STOP) 42
using as templates 184
annotation toolbar 167
Page Setup Wizard 167
Previous Zoom 167
Raster to Vector Conversion 167
Save Image to Clipboard 167
Index
Scattergrams 167
Setup Algorithm Page Size 167
Traverse extraction 167
Zoom to Contents Extents 168
Zoom to Page Extents 168
annotation. See map composition
Application Examples 6
Applications - image processing 10
ARC/INFO
dynamic links to 235
ARC/INFO coverages 17
Aster 14
ASTER Data Processing Wizard 188
Aster toolbar 168
Autoclip transforms 89
setting percent clip 89
using toolbar 90, 94
Azimuthal Equidistant map projection 243
B
background color 226
batch processing toolbar 168
Batch Reprojection Wizard 168
Change Datum/Projection/Cell Size Wizard
168
Contact Sheet Wizard 168
HDF Import Wizard 168
HGT Batch Import Wizard 169
Manage large algorithms 168
Map Collar Wizard 168
MapInfo .tab file Wizard 169
Batch Script/wizard Control 227
Bipolar Oblique Conic Conformal map projection 243
BMP 14
Bonne for North America map projection 243
borders 226
buttons 163
formula 186
C
cascading filters 185
Cassini-Soldner map projection 243
Cell Values Profile dialog 66
Change Detection, using the LCAW 216
Change Projection/Datum/Cell Size Wizard
193
class statistics 231
classification
displaying 232
ISOCLASS unsupervised classification 232
supervised 231
unsupervised 232
257
classification toolbar 169
Area Summary Report 169
Calculate Dataset Statistics 169
Define Regions 169
Distance Between Means Report 170
Edit Region details 169
ISOCLASS Unsupervised Classification
170
Landsat TM Wizard 169
Means Summary Report 170
Raster to Vector Conversion 170
Regions to Vectors Conversion 169
Scattergrams 170
Show Dataset Statistics 169
Standard Deviation Summary Report 170
Supervised Classification 170
Vectors to Regions Conversion 169
color
background 226
choosing for classified data 232
Color Mode
Hue Saturation Intensity 52
Pseudocolor 52
Red Green Blue 52
relation to layer type 53, 57
comments
defining 47
viewing 47
common functions toolbar 163, 166
Annotate Vector Layer 166
Browse the ER Mapper website 167
Contouring Wizard 166
Edit Algorithm 166
Edit Filter (Kernel) 167
Edit Formula 167
Edit Realtime Sun Shade 167
Edit Transform Limits 167
Gridding Wizard 166
Image Balancing Wizard for Airphotos 166
Image Display and Mosaic Wizard 166
Load Dataset 166
Ortho and Geocoding Wizard 166
Common Geophysical Images Wizard 193
composing maps. See map composition
compression 208
Compress for Internet 203
compression ratio 117
compression toolbar 170
Image Compression Wizard 170
Manage large algorithms 227
Report on a compressed file 170
Start ECW Cache Monitor 170
Compression Wizard
current image window 207
258
file stored on disk 207
saving the compressed image 208
Conic Equidistant map projection 243
Contact Sheet Wizard 194
Contouring Wizard 196
contrast enhancement. See transforms
creating
virtual datasets 251
D
Danish Universal Transverse Mercator map
projection 244
data
integrating raster and vector 235
Data formats 14
Data read/import 14
data structure diagram 38
data support 14
Data Type Examples 6
Database
linking to 17
datasets
classifying 231
mosaicing using virtual datasets 251
viewing a portion 251
virtual 251
default hardcopy device 226
DEM toolbar 170
Contouring Wizard 171
Create Aspect Algorithm 171
Create Slope (degrees) Algorithm 171
Create Slope (percent) Algorithm 171
density slicing. See transforms
dialog boxes 24
text entry 26
differences 186
disk storage and virtual datasets 251
displaying datasets 41, 48
displaying images 41, 48
DOQQ 14
DXF files
linking to 17
dynamic link chooser 235
Dynamic Link layers 17
dynamic links 17, 235
E
ECW 14
EODIS 14
ER Mapper
compressed image
.ecw 14
dialog boxes 24
Index
file choosers 24
help system 26
introduction 9
main menu 22, 161
raster datasets 14
.ers 14
raster images 14
toolbars 23
user interface 21
vector datasets 15
vector images 15
ESRI BIL
.hdr 14
example algorithms 185
exponential transforms 91
exporting data 18, 241
extents of the algorithm, setting 226
F
feathering mosaic seams 130
FFT processing, see Fourier processing
file chooser dialog boxes 24
film writers 247
filter program in printing 248
Filters
cascading 185
DEM 185
Edge 185
Gaussian 185
Geophysics 185
High pass averaging 186
Low pass averaging 186
Ranking 186
SAR 186
Seismic 186
Standard 186
Sunangle 186
Usercode 186
Force 1 dataset cell option in Print Setup 248
forestry toolbar 171
Create Aspect Algorithm 173
Create Brovey Transform 172
Create RGB Algorithm 173
Create RGB Principal Components 123 Algorithm 173
Create Slope (degrees) Algorithm 173
Create Slope (percent) Algorithm 173
Highlight Cloud 172
Highlight Vegetation 172
Highlight Water 172
Landsat TM Wizard 172
Show Tabular Data 174
Vegetation Changes 172
259
formula button 186
formulae 186
autoscaling data 94
NDVI 43
full spectrum frequency datasets 237
functions 186
Functions and Features Examples 7
G
gamma correction 248
Gaussian equalization 90
setting std. dev. 90
generic formula 186
geocoding 15
geolink
none 239
overview zoom and overview roam 240
screen 239
window 239
geolinking windows 239, 240
geophysics toolbar 174
Common Geophysical Images Wizard 174,
194
Create 1Q Vertical Derivative Algorithm
174
Create 2nd Vertical Derivative Algorithm
175
Create 3Q Vertical Derivative Algorithm
175
Create Pseudocolor Algorithm 174
Create Ratio K/Th Algorithm 174
Create RGBI Colordrape Algorithm 174
Fast Fourier Transforms 174
Magnetics Fourier Wizard 174
magnetics Fourier wizard 237
Mineral Exploration Wizard 175
Traverse 174
geoposition window 239
GeoSPOT
hdr 14
GeoTIFF/TIFF
.tif/.tiff 14
GIS systems
ARC/INFO coverages 17
linking to 17
GIS toolbar 175
ARC/INFO Direct Access Link 175
MapInfo .tab File Reader 175, 181
Raster to Vector Conversion 175
Show Tabular Data 175
Gnomonic map projection 244
graphics formats
exporting to 19
Index
using in map composition 152
Grey Level Co-occurrence Matrices (GLCMs)
178
gridding
input sources 200
project file 200
Gridding Wizard 198
H
half spectrum frequency datasets 237
hardcopy 247
default device 226
hardcopy printing 18
HDF 14
HDF Import Wizard 201
help 3
help system 26
HGT Batch Import Wizard 169, 227
histogram equalization 90
histogram matching 127
histograms. See transforms
Hotine Oblique Mercator map projection 245
HSI color mode 52
HSI Color Wheel 211, 221
HSI merge technique 135
I
“if” tests 186
IHS merge technique 135
Image Balancing Wizard 204
Image Balancing Wizard for Airphotos 111
Image Compression Wizard 115, 206
Image display 15
Image Display and Mosaic Wizard 103, 105,
209
Image enhancement 16
image files. See raster images
Image geocoding 15
Image mosaicing 16
Image processing
applications 10
concepts 9
tasks 13
Traditional 11
image processing
applications 10
concepts 9
contrast enhancement 77
enhancements 15
ER Mapper algorithms 12
general tasks 13
traditional techniques 11
viewing data values 67
260
Image processing concepts 9
Image Subset Wizard 227
image windows
closing 36
loading datasets 41, 48
loading images 41, 48
measuring distances 69
moving 30
moving to front 35
opening 29
panning with buttons 32
resizing 30
selecting current 35
shaping to fit image 108, 122
using multiple windows 34
viewing cell values 66
viewing coordinates 68
zooming with buttons 32
zooming with mouse 31
images
scale 226
importing data 241
Installation of example images and algorithms
6
integrating data 235
ISOCLASS classification 232
J
JPEG
.jpg
.jgw 14
JPEG 2000
input image 14
L
Laborde Oblique Mercator map projection 244
Lambert Azimuthal Equal-Area map projection
244
Lambert Conformal Conic with One Standard
Parallel map projection 244
Lambert Conformal Conic with Two Standard
Parallels map projection 244
Land Applications Wizard (LAW) 211
Landsat 7 FastL7A
.fst 14
Landsat TM Wizard 213
Landsat Web Publishing Wizard 213
Landsat Web Publishing Wizard button 181
Landsat7 14
LAW-Land Applications Wizard 211
Layer tab 39
layers 38
adding 62
Index
Annotation/Map Composition 133
changing order 61
changing type 63
controls 51
deleting 61
duplicating 62, 121
labelling 44, 45
loading data into 58
modifying 54
moving between 63
overview 51
raster types 53
selecting 56
selecting bands 62
setting display priority 123
turning on and off 56
vector types 54
with Color Mode 57
Level slice transform
setting levels 91
Line Style dialog box 144
linking windows 239, 240
links to external data 17
loading datasets 41, 48
loading images 41, 48
Local Council Applications Wizard 215
logarithmic transforms 91
logical conditions 186
lookup tables 42
M
Machine Configuration Report Wizard 227
Magnetics Fourier Wizard 217, 237
magnifying images. See zooming
Map Collar Wizard 218
map composition 17
basic concepts 133
drag and drop objects 149
drawing annotation 144
drawing map objects 147
importing graphics formats 152
importing text 152
object attributes 152
page background color 138, 139
Page Relative option 153
polygon attributes 145
polyline attributes 144
resizing/positioning objects 151
saving to disk 151
selecting objects 144
setting map object attributes 149
setting up a page 135
special features 152
261
text attributes 146
MapInfo .tab File Wizard 169, 219
MapInfo .tab files 219
masking regions 186
measuring distances 69
mensuration 69
Mercator map projections 244
MEW - Mineral Exploration Wizard 220
Miller Cylindrical map projection 244
Miller Stereographic (Sphere) map projection
245
Mineral Exploration Wizard (MEW) 220
minerals toolbar 175
Common Geophysical Images Wizard 176
Create Abrams Ratio Algorithm 176
Create Clay Ratio/Magnetics Colordrape
176
Create Ratio K/Th Algorithm 176
Create Realtime Shade Algorithm 176
Create RGB Principal Components 123 177
Create RGBI Colordrape Algorithm 176
Landsat TM Wizard 176
RGB 741/Magnetics Colordrape 176
Miscellaneous 7
Modified Polyconic map projection 245
MODIS 14
Mollweide map projection 245
mosaicing
analyze images 112
capabilities 103
compressing 115
creating algorithms 111, 120
creating mosaiced image 97, 104
display band 107
display method 107
feathering 113
feathering seam lines 129
file types 106
histogram matching 127
Image Display and Mosaic Wizard 103
mosaic properties 107
RGB 123 110
setting display priority 103, 123
turning images on/off 109, 123
using RGB algorithms 124
using virtual datasets 251
zooming to all datasets 121
mouse buttons 21
mouse pointer
Hand mode 32
Pointer mode 67
shapes 22
Zoom mode 30
ZoomBox mode 31
Index
multi-band datasets 186
multi-resolution merging
using IHS technique 135
multispectral data 10
O
oil and gas toolbar 177
3D Horizon Amplitude 177
3D Shaded Horizon 177
Common Geophysical Images Wizard 177
Create 3D Horizon 177
Horizon Azimuth 177
Horizon Dip 178
Horizon IHS 178
Horizon RTS 178
open from virtual dataset 251
Oracle, dynamic links to 235
orientation in print setup 248
Ortho and Geocoding Wizard 15, 222
orthographic projection 245
orthorectification 15
output program for printing 248
overview roam geolink option 240
overview zoom geolink option 240
P
page borders 226
Page Setup dialog box 136
Page Setup Wizard 225
page size of algorithms 225
panning images
with buttons 32
with mouse 32
Polar Stereographic map projection 245
polygon attributes 145
polyline attributes 144
Postscript files
linking to 17
printing to 19
using in map composition 133
PostScript, dynamic links to 235
prevent wrapping in Fourier processing 237
principal components 186
print setup 247
printers 247
printing 247
default device 226
filter program 248
gamma correction 248
output program 248
printing images 18, 153
process stream diagram 39
profiles across datasets 70
262
profiles of data. See Traverse 69
project files 200
Pseudocolor color mode 42, 48, 52
R
radar common toolbar 178
import polarimetric data 179
layover and shadow map generation 178
polarization signature 179
remove antenna pattern noise 178
remove speckle noise 178
SAR image simulator 178
slant to ground conversion 178
texture analysis 178
radar filters toolbar 179
frost 179
k-nearest neighbor lee 179
k-nearest neighbor weighting (mtf) 179
lee 179
sigma 179
symmetric nearest neighbor lee 179
symmetric nearest neighbor weighting
(mtf) 179
weighting (mtf) 179
raster and vector data integration 235
raster data
importing and exporting 241
raster data formats 241
Raster Dataset dialog 58
Apply button 59
Apply vs OK 60
raster datasets
description 9
importing 14
merging 135
mosaicing 103
reading 14
rescaling data range 88, 94
viewing cell values 67
raster GIS functions 186
raster images 10
description 9
importing 14
merging 135
mosaicing 103
reading 14
rescaling data range 88, 94
viewing cell values 67
raster layers
formulae in 186
relation to Color Mode 53
types 53
ratios 186
Index
Rectified Oblique Mercator map projection
245
Rectified Skew Orthomorphic map projection
243
reduced precision in fourier processing 237
reducing data complexity with virtual datasets
251
reducing disk storage with virtual datasets
251
Refresh Image button 30
Refresh Image with 99% clip button 94
region statistics 186
regions
classifying 231
Regular Polyconic map projection 245
remote sensing toolbar 179, 215
Clay Ratio 180
Create Brovey Transform 180
Create RGB Principal Components 123 Algorithm 180
Highlight Cloud 179
Highlight Vegetation 179
Highlight Water 179
Iron Oxide ratio 180
Land Application Wizard 180
Landsat TM Wizard 179
Local Council Applications Wizard 180
Reprojection on-the-fly 103
rescaling data
using transforms 88
RESTEC/NASDA CEOS
.dat 14
RGB color mode 52
roaming using overview roam geolink mode
240
Robinson Pseudocylindrical map projection
245
S
saving images 18
scale in printing 247
scale of the image 226
Scanned map and airphoto integration 216
Scattergram Setup dialog box 73
scattergrams
changing bands 73
Defer button 75
Display button 75
viewing 72
screen geolinking 239
Setting up practice images 6
shaded relief images 100
Sinusoidal map projections 245
263
Southern Transverse Mercator map projection
245
specific formulae 186
spectral signatures
averaging 68
viewing 67
Spot Vegetation 14
standard toolbar 163, 164
99% Contrast Enhancement 166
Copy Window 164
Hand (Roam) Tool 165
new (image window) 164
Open (algorithm into image window) 164
Pointer Tool 165
Print 165
Refresh (image) 165
save algorithm 164
Save As 165
stop processing 166
Zoom Tool 165
Zoombox Tool 165
statistics 233
for formulae 186
Stereographic (oblique) map projection 244
sun angle shading
with colordraping 100
supervised classification 231
surfaces 38
Swiss Cylindrical map projection 245
T
tab file reader 193, 219
tab pages 38
table (.tab) files 220
tabular data links 17
template algorithms 185
for autoscaling data 94
text attributes 146
Text Style dialog box 146
TIFF 14
toolbars
annotation 167
Aster 168
batch processing 168
classification 169
Compression 170
DEM 170
displaying 28
forestry 171
geophysics 174
GIS 175
hiding 28
minerals 175
Index
oil and gas 177
overview 23
radar common 178
radar filters 179
remote sensing 179
standard 164
turning on and off 163
using 28
web publishing 180
wizards 181
Transform dialog box 78
transforms
adjusting line 81
appending 93
automatic options 89
automatically clipping on limits 94
deleting 92
exponential 91
Gaussian equalization 90
highlighting features 84
histogram clipping 89
histogram equalization 90
histogram matching 127
inserting 92
level slicing 91
linear 81
logarithmic 91
overview 77
piecewise 84
rescaling data with 88
setting input limits 86, 87
setting output limits 88
using multiple 92
viewing 80
viewing for other layers 63
viewing next in stream 93
viewing previous in stream 93
Transverse Mercator map projection 245
Traverse dialog box 70
Traverse Extraction 69
drawing traverse lines 69
modifying traverse lines 71
selecting dataset bands 70
Tutorial
Getting started 6
installing examples 6
Setting up practice images 6
Typographical conventions 8
U
Universal Transverse Mercator map projection
245
unsupervised classification 232
264
User interface components 21
USGS
Digital Ortho Quad
.doq 14
V
Van der Grinten map projections 244
vector data
importing and exporting 241
vector data formats 241
vector datasets
display color 143
displaying 140, 142
editing 143
vector images
display color 143
displaying 140, 142
editing 143
vector layers 54
vegetation index formulas 43
vegetation indexes 186
View Mode 38
viewing a portion of a dataset 251
viewing data values 65
virtual datasets 251
W
web publishing toolbar 180
landsat web publishing wizard 181
windows
geolinking 239, 240
linking 239, 240
windows geolink option 239
windows. See image windows
Wizards
3-D Algorithm Wizard 187, 193
ASTER Data Processing Wizard 188
Change Projection/Datum/Cell Size Wizard
193
Common Geophysical Images Wizard 193
Contact Sheet Wizard 194
Contouring Wizard 196
Gridding Wizard 198
HDF Import Wizard 201
HGT Batch Import Wizard 227
Image Balancing Wizard 204
Image Compression Wizard 206
Image Display and Mosaic Wizard 209
Image subset Wizard 227
Land Applications Wizard (LAW) 211
Landsat TM Wizard 213
Landsat Web Publishing Wizard 213
Local Council Applications Wizard 215
Index
Machine Configuration Report Wizard 227
Magnetics Fourier Wizard 217
Map Collar Wizard 218
MapInfo .tab File Wizard 219
Mineral Exploration Wizard (MEW) 220
Ortho and Geocoding Wizard 222
other 227
Page Setup Wizard 225
wizards toolbar 181
3-D Algorithm Wizard 181
Batch Script/Wizard Control 181
Common Geophysical Images Wizard 181
Contouring Wizard 181
HDF Import Wizard 181
Image Compression Wizard 181
Landsat TM Wizard 181
Magnetics Fast Fourier Transformations
Wizard 182
Map Collar Wizard 181
Page Setup Wizard 182
work area in Fourier processing 237
wrapping in Fourier processing 237
Z
zooming images
out to full extents 32, 33
to page extents or contents 142
to specific dataset extents 110, 124
with buttons 33
with mouse 31
265
Index
266
Index
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