Geographic Imager Tutorial Guide

Geographic Imager Tutorial Guide
®
for Adobe Photoshop
Tutorial Guide
Geographic Imager 4.5 Tutorial Guide
Copyright © 2005–2014 Avenza® Systems Inc. All rights reserved.
Geographic Imager® 4.5 for Adobe® Photoshop® Tutorial Guide for Windows® and Mac®.
Geographic Imager is a registered trademark of Avenza Systems Inc. Adobe, Adobe Photoshop and Adobe
Illustrator are trademarks of Adobe Systems Inc. or its subsidiaries and may be registered in certain jurisdictions.
Blue Marble Geographics, GeoTransform and The Geographic Transformer are trademarks of Blue Marble
Geographics. All other software product names and brands including trademarks or registered trademarks are the
property of their respective owners.
This tutorial guide and the software described in it are furnished under license and may be used or copied only
in accordance with the terms of such license. The content of this manual is furnished for informational use only,
is subject to change without notice and should not be construed as a commitment by Avenza Systems Inc. or its
related companies or successors. Avenza Systems Inc. assumes no responsibility or liability for any errors, omissions
or inaccuracies that may appear in this book.
Except as permitted by such license, no part of this publication may be reproduced, stored in a retrieval system,
or transmitted, in any form or by any means, electronic, mechanical, recording, or otherwise without prior written
approval of Avenza Systems Inc.
Avenza Systems Inc.
124 Merton Street, Suite 400
Toronto, Ontario, M4S 2Z2
Canada
Tel: (+1) 416 487 5116 Toll Free (North America): 1 800 884 2555
Fax: (+1) 416 487 7213
Email: info@avenza.com
Web: www.avenza.com
Support Tel: (+1) 416 487 6442
Support email: support@avenza.com
Portions of this computer program are copyright ©2007 Leica Geosystems Geospatial Imaging, LLC. All rights reserved. Creating compressed files using ECW technology is
protected by one or more of U.S. Patent No. 6,201,897, No. 6,442,298 and No. 6,633,688.
Portions of this computer program are copyright © 1995-2008 Celartem, Inc., doing business as LizardTech. All rights reserved. MrSID is protected by U.S. Patent No. 5,710,835.
Foreign Patents Pending.
Geographic Imager 4.5 Tutorial Guide for Adobe Photoshop, September 2014
© 2014 Avenza Systems Inc.
Printed in Canada
Contents
Contents
Open Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Specify a Reference File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Specify a Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Transform a Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Mosaic Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Tile Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Georeference an Image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Quick Georeference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Quick Save to Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
GeoCrop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Import DEM File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Terrain Shader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Reset Import DEM File Schema and Advanced Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Advanced Import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Advanced Import of DEM files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Export Web Tiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Adobe Photoshop Tutorial Exercises
Using Actions with Geographic Imager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Create a 3D Representation with a Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
The Ruler Tool and Measure Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Create a False-Colour Composite with Multiple Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Create a False-Colour Composite with Channel Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Pan Sharpen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Resample and Sharpen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
In this tutorial you will learn the basics of Geographic Imager by working with a series of tutorial exercises. All of the
sub-folders of files, images, data and scripts for the tutorial exercises can be found in the following locations:
Windows XP
C:\Documents and Settings\All Users\Documents\Avenza\Geographic Imager\User Guide, Tutorial & Data
Windows Vista/7/8
C:\Users\Public\Public Documents\Avenza\Geographic Imager\User Guide, Tutorial & Data
Mac OS X
/Applications/Avenza/Geographic Imager/User Guide, Tutorial & Data
Geographic Imager Tutorial Guide
3
Tutorial Exercises
Open Images
Opening a spatial image is similar to opening up any other image.
1. In Adobe Photoshop, choose File > Open. Browse to the Tutorial Data folder containing the tutorial images and
open EuropeLL.tif and EuropeTR.tif.
2. Make the EuropeTR.tif file the active document and view the Geographic Imager panel. If the panel is not
visible, choose Window > Extensions > Geographic Imager.
3. Keep these images open for the next exercise.
Specify a Reference File
A reference file contains coordinates that describe the location, image size, pixel size, and rotation of an image file.
It does not contain actual image data.
1. With the EuropeTR.tif file as the active document, click the Reference File Specify... link in the Geographic Imager
panel. This specifies a reference file containing geographic coordinate information for the active document.
2. Select EuropeTRref.tfw and click the Open button. The reference file will be listed in the Geographic Imager panel.
3. Keep these images open for the next exercise.
4
Geographic Imager Tutorial Guide
Specify a Coordinate System
Some reference files do not store coordinate system information. Using a world file as a reference file requires that
a source coordinate system be specified. For more information on reference files, see Chapter 2 in the Geographic
Imager User Guide.
The EuropeTR.tif was originally made in the WGS 84 coordinate system, however it currently has no coordinate
system assigned. Specify a coordinate system using these steps.
1. With the EuropeTR.tif file still the active document, click the Coordinate System Specify... link in the Geographic
Imager panel. This specifies a coordinate system for the active document.
2. In the Specify Coordinate System dialog box, click the [No Coordinate System Specified] link.
3. In the Select Coordinate System dialog box, expand the Coordinate Systems > Geodetic > World category, select
the WGS 84 in the coordinate system list and click OK.
4. Click OK in the Specify Coordinate System dialog box.
This assigns the WGS 84 coordinate system to the active document and is reflected in Geographic Imager panel.
5. Keep these documents open for the next exercise.
Geographic Imager Tutorial Guide
5
Transform a Coordinate System
Transforming a coordinate system transforms a georeferenced source image into a destination georeferenced
image with a different coordinate system. In this exercise, the image will be transformed from WGS 84 coordinate
system to British National Grid coordinate system.
1. With EuropeTR.tif still the active document, click the Transform button
in the Geographic Imager panel.
2. In the Transform dialog box, click the WGS 84 link to select a destination coordinate system. This is different than
specifying a source coordinate system. A destination coordinate system is the coordinate system of the image
after it is transformed.
3. Expand the Coordinate Systems > Projected > Europe > United Kingdom category, select British National Grid from
the coordinate system list and click OK.
This sets the coordinate system that will be used during the transformation. At this point, Geographic Imager
automatically selects an appropriate datum shift to be performed during the transformation process. If this
datum shift needs to be changed, click the Specify button to open the Specify Datum Shift dialog box and select
the desired datum. See page Geographic Imager user guide for an explanation of datum shift.
4. Change the Pixel Size to 1234.8, leave the other options as the defaults.
The pixel size can be changed to any user specified value. This essentially changes the size of the image as each
pixel represents a geographic unit. In this instance, the value was chosen to be near the original value.
6
Geographic Imager Tutorial Guide
5. Click the Transform button in the Transform dialog box. The image is transformed to a British National Grid
projected coordinate system.
6. Make the EuropeLL.tif file the active document and click the Transform button. The panel displays the coordinate
system as WGS84. You’ll transform it to British National Grid.
7. Click the Same As check box and select EuropeTR.tif (British National Grid) from the Same As drop-down list.
8. Click Update pixel dimensions to match the selected document when prompted.
9. Click the Transform button in the Transform dialog box to confirm these settings.
Geographic Imager Tutorial Guide
7
Both images are now in the same projected coordinate system (British National Grid) and have the same
pixel size.
10. Close all documents without saving before proceeding to the next exercise.
8
Geographic Imager Tutorial Guide
Mosaic Images
In the next set of exercises, several image documents will be mosaicked together, transformed as one image, and
exported as multiple image tiles.
1. In Adobe Photoshop, open the EuropeTL.tif, EuropeLL.tif, EuropeLR.tif and EuropeTR.tif files.
2. Make the EuropeTR.tif file the active document, click the Reference File Specify... link in the Geographic Imager
panel, choose EuropeTRref.tfw as the reference file, and click Open.
3. Click the Coordinate System Specify... link in the Geographic Imager panel, select one of the other images in the
Same As drop-down list to specify the coordinate system as WGS 84 (EuropeLR.tif or EuropeLL.tif ) and click OK.
4. Make the EuropeTL.tif the active document and click the Mosaic button
.
Notice that EuropeTL.tif is in the British National Grid coordinate system. It will be the destination document,
meaning other images will be mosaicked and transformed into it. Available documents can have different
coordinate systems, different pixel sizes or contain rotation and still be mosaicked. The images will inherit the
coordinate system and pixel size of the destination document.
Note: Transformations during mosaic are not supported when the destination document contains rotation. To
mosaic into a destination document containing rotation the images to be mosaicked must have the same
coordinate system, pixel size and rotation angle.
A list of available documents for mosaicking are displayed in the Available Documents list of the Mosaic dialog
box. You will specify the Mosaic Documents next.
5. Click the Select All button to select all available images and click the double right arrow button to move them
into the Selected Documents list. Click the Keep source data on separate layers check box.
Geographic Imager Tutorial Guide
9
The Advanced Transformation Options in the Mosaic dialog box are the same as the Transform dialog box. These
options are used to resample the layers, set strip size and leave the layers intact or merge them. In this tutorial, leave
them at their default settings. Read more about these options in chapter 4 of the Geographic Imager User Guide.
6. Click OK to complete the mosaic.
The image is mosaicked in the EuropeTL.tif document window with a coordinate system of British National Grid.
Inspect the Adobe Photoshop Layers panel. Notice that the other documents are now mosaicked in the
EuropeTL.tif document. The layers are kept intact because you specified it to be. However, there is no need to
retain the layer structure and the image will be flattened in the next exercise.
7. Close all documents without saving before proceeding to the next exercise.
10
Geographic Imager Tutorial Guide
Tile Images
1. In Adobe Photoshop, open EuropeMosaic.tif.
2. Click the Tile button in the Geographic Imager panel.
3. In the Tile dialog box, select the By Number of Tiles option, and type 3 into both the Horizontal and Vertical text
boxes. This will result in the creation of nine new images.
4. In the Overlap frame, type 10 into both Horizontal and Vertical text boxes. Ensure Pixels is chosen in the Units
drop-down list. This creates an overlap with each of its adjacent images.
5. In the Naming drop-down list, select Separate Row/Column Numbers. Each image will contain the name of the
original image plus a reference to the row and column to which it represents.
6. Select GeoTIFF/BigTIFF/TIFF from the Reference File Format drop-down list and click OK.
7. Click OK and specify a location (directory) to save the tile images. In this case, use the default file name and click
Save. If a TIFF Options dialog box appears, click OK to accept the default settings.
8. When the tile process is completed, navigate to the destination directory and view the tile images. The
naming separate row/column numbers format is appended to the file name: the tile EuropeMosaic_1_1.tif
belongs in the first row and first column; EuropeMosaic_1_2.tif in the first row and second column; and
EuropeMosaic_1_3.tif in the first row and third column, and so on.
9. Close all open documents without saving.
Geographic Imager Tutorial Guide
11
Georeference an Image
The image for this exercise is a satellite image of central Rio de Janeiro, Brazil, courtesy of Google® Earth. The image
has no georeferencing, however it has four red pushpins indicating the position of placed ground control points.
Using the Georeference command, assign a real world position to each control point.
1. In Adobe Photoshop, browse to the tutorial folder and open Rio de Janeiro.jpg.
Note that in the Geographic Imager panel, the Reference File field is not specified because no corresponding
reference file is present in the image folder.
2. In the Geographic Imager panel, click the Georeference button.
The image is in a Pseudo-Mercator projection (as used in Google Earth and Google Map) but the position of the
control points are provided in latitude and longitude format in the WGS84 geodetic system.
3. In the Format frame, click the Specify... link to set the Image Coordinate System.
4. In the Input Format dialog box, click the [No Coordinate System Specified ] link to specify the image coordinate system.
5. Expand the Coordinate Systems > Projected > World category, select WGS84 / Pseudo-Mercator and click OK.
6. Back in the Input Format dialog box, click the Use alternate input coordinate system check box to enable this option
and click the corresponding [No Coordinate System Specified ] link. This ensures that the world values being entered
are those of the coordinate system chosen in the next step.
7. Expand the Coordinate Systems > Geodetic > World category, select WGS84 and click OK. In the dialog box that
appears, click Convert the points to the new coordinate system.
8. Back in the Input Format dialog box, choose Decimal Degrees (D+[.d*]) from the Geodetic Coordinates Format
drop-down list, change the Geodetic Precision to 6, and click OK.
12
Geographic Imager Tutorial Guide
9. At the top of the Georeference dialog box, click the Zoom In button
located at the upper-left corner of the image.
and zoom to the first control point
Note: If the overview window is in the way, close it by clicking the Show/Hide Overview button
or move it—
right-click (or hold Ctrl or Cmd and click) the overview window and drag to a new position.
10. Click the Add Point button
and click precisely at the tip of the red pushpin number 1 on the image preview
(zoom-in more if necessary). This adds a first control point named Point 1, a new row is added in the control
point table.
11. In the control point table, enter the world coordinate (WX longitude and WY latitude) for Point 1 (top-left):
•
•
WX= -43.256355
WY= -22.872398
12. Using the Zoom In
, Zoom Out
, Zoom to Extent
and Pan
buttons or the overview window (click
and drag to draw new extents), magnify the location of the red pushpin number two on the upper right corner
of the image.
13. Click the Add Point button
and click precisely at the tip of second pushpin.
14. In the control point table, enter the world coordinate for Point 2 (top-right) as follow:
•
•
WX= -43.243635
WY= -22.872597
Geographic Imager Tutorial Guide
13
15. Repeat the same procedure for red pushpin number 3 in the lower right corner of the image. The world
coordinate for Point 3 (lower right) are:
•
•
WX= -43.242564
WY= -22.884070
16. Repeat the same procedure for the fourth red pushpin in the lower left corner of the image. Notice that the
world coordinates of the fourth point are populated with an estimation based on the position of the other
control points.
Note: The registration Method is set by default to Affine—this method requires a method of three points (usually
four for control). When using a higher polynomial degree method (e.g. Cubic Polynomial) more control points
are required to determine the image registration. Higher polynomial degree methods can be necessary for
distorted images (skewed through scanning process for example), or if the chosen image coordinate system
is approximative.
17. Instead of keeping the estimated world coordinates of Point 4 (lower left), change them as follow:
•
•
WX= -43.255150
WY= -22.883450
The control point table contains several columns on the positioning error of each control point (in pixel or world
unit). The world coordinate values entered are considered accurate for this exercise, so any error should be due
to the position of the control point on the image preview.
18. To reduce the error values, center and magnify the image preview to a control point to be moved, then click the
Select Points button
and click and drag the desired location to a more precise pixel position. Look at the
error columns in the control point table to see if this improves the positioning accuracy. A WX and WY error of
0.5 meters is very acceptable for this image.
19. Leave the Mode as GCP and click OK. Click Continue using the GCP mode in the command box.
14
Geographic Imager Tutorial Guide
The image is now georeferenced. The Geographic Imager indicates a reference named Rio de Janeiro.tfw file and
the selected image coordinate system (WGS84 / Pseudo-Mercator). The World (tfw) reference file format is the
default reference format. It can be changed in Geographic Imager Preferences (Panel options menu > General
Options > Preferences > Default Reference Format). The Mode (stated in the Georeference dialog box) is GCP and
contains the four points that you defined.
20. To save the reference file and image file (although the image itself has not been modified), choose File > Save in
the Adobe Photoshop main menu. The reference file, Rio de Janeiro.tfw, is saved in the same folder as the image
file. Click Proceed with the selected reference format in the command box regarding the storage of individual ground
control points.
21. Close all documents and continue with the next exercise.
Geographic Imager Tutorial Guide
15
Quick Georeference
Quick Georeference is a fast method to georeference an image. This method requires two conditions:
•
•
The image is not rotated (image aligned to True North).
Only two points are needed to georeference, however these points must not contain the same coordinate
in either the X or Y pixel or world unit (i.e. two points cannot be aligned on the same X or Y axis on either the
image or world system).
1. In Adobe Photoshop, open EuropeTR.tif. The image is not rotated and is aligned to True North.
2. In the Geographic Imager panel, click the Georeference button.
3. In the Georeferencing dialog box, click the Add Control Point button
twice. In the table below, type the pixel
coordinates (PX and PY) and world coordinates (WX and WY in decimal degrees) of two points located at the
Northeast and Southwest corners of the image:
Northeast point (Point 1)
PX = 419, PY pixel = 0
WX = 1.76, WY = 60.00
Southwest point (Point 2)
PX = 0, PY = 452
WX = -2.89 WY = 54.98
Notice that the world coordinates expand to three decimal places. This happens because the Projected Precision
is set to three decimal places.
16
Geographic Imager Tutorial Guide
4. Click the Quick Georeference button and select the option By Two Reference Points (North/South aligned).
The image is now georeferenced and two additional reference points are added. If necessary, click and drag
the horizontal line below the image view to adjust the size of the table. Notice that there are no pixel or world
coordinate errors.
5. In the Format frame, click the Image Coordinate System Specify... link.
Geographic Imager Tutorial Guide
17
6. In the Input Format dialog box, click the [No Coordinate System Specified ] link. In the Specify Source Coordinate
System dialog box, expand the Coordinate Systems > Geodetic > World category, select the WGS 84 coordinate
system and click OK.
7. Click OK to close the Input Format dialog box.
The Format frame coordinate information is updated.
8. In the Georeference dialog box, click OK to save the settings.
The document was successfully georeferenced.
9. Keep this image open for the next exercise.
18
Geographic Imager Tutorial Guide
Quick Save to Format
Quick Save to Format is used to save an image into another format. The supported formats are BigTIFF, ECW, ERDAS
IMAGINE Raster, Geospatial PDF, GeoTIFF, MrSID, and NITF.
1. With EuropeTR.tif as the active document from the previous exercise, click the Geographic Imager panel options
menu and choose Quick Save to Format.
2. In the Quick Save to Format dialog box, choose Geospatial PDF as the Image format and click OK.
3. In the Save dialog box, choose a location to save the Geospatial PDF. Specify the name of the image as
EuropeTRdocument.pdf and click Save.
The reference information is saved in the Geospatial PDF file and is displayed in the Geographic Imager panel as
the reference. A geospatial PDF contains everything, including the image and reference information.
4. Close all open documents without saving.
Geographic Imager Tutorial Guide
19
GeoCrop
The GeoCrop function crops georeferenced images based on defined crop areas.
1. In Adobe Photoshop, open EuropeLL.tif and click the GeoCrop button
in the Geographic Imager panel.
2. In the GeoCrop dialog box, choose Geodetic from the Unit Type drop-down list. Leave the Coordinate Format as
Decimal Degrees and type in the following values:
Top-left corner
Long: -5.5 deg
Lat: 52.5 deg
Bottom-right corner
Long: -4.5 deg
Lat: 51.5 deg
The crop area marquee (dashed red border shown in the image preview) is drawn to the coordinates specified
above. This functions similarly to the Adobe Photoshop crop tool. You’ll resize it to change the crop area.
20
Geographic Imager Tutorial Guide
3. Click and drag a corner of the crop area marquee to resize it. If needed, click and drag to move it.
As the marquee is resized, the corner coordinate values are updated.
4. Click OK to complete the GeoCrop.
5. Close all open documents without saving.
Geographic Imager Tutorial Guide
21
Import DEM File
Import DEM files easily using Geographic Imager. Some DEM files contain background or water areas (usually at
a zero height) and need to be isolated before it can be styled. To achieve this, background pixels areas have to be
defined in the Import DEM file dialog box advanced settings.
1. In Adobe Photoshop, browse to the Tutorial Data folder and open Yukon Water.dem.
2. In the Import DEM file dialog box, click the Create New Schema button
.
This opens the Edit DEM Schema dialog box. The Schema Name is already populated with the name of the file. It
also populates the Lowest and Highest Elevation values according to the DEM’s data range.
3. Since these values do not need to be modified click OK to close the Edit DEM Schema dialog box.
The Select Schema now reflects the data range of the DEM.
22
Geographic Imager Tutorial Guide
4. In the Import DEM file dialog box, click the Advanced button.
The Unique values list is currently set to Display as transparent pixels. The value -32767.00 is a predefined value
that represents no data. This value can not be deleted and is common to all DEM files. To display elevations as
transparent pixels, populate this list with elevation values.
5. Click the Add new value button
. A new value is created. Double-click <new value> and type in a value of 0.
6. Click OK to close the Advanced DEM Schema Settings and click OK to accept the settings of the Import DEM file
dialog box to finish the import.
Geographic Imager Tutorial Guide
23
The chosen custom DEM schema maps the range of elevation to the Adobe Photoshop grayscale color-space,
displaying the highest contrast possible. A transparent area is visible where all elevations with a value of 0 that
was specified in Advanced DEM Schema Settings.
The elevation value of 0 is considered water for this DEM. Since the area that represents water is now
transparent, it is now very easy to create a background layer and apply a different color to it (remember that the
color-space is grayscale).
7. Create a new layer and rename it to Background. Use the Adobe Photoshop Paint Bucket Tool and fill the layer
with a black color (R: 0, G: 0, B:0).
In the next tutorial, you will apply a gradient map to the elevation data layer using the Terrain Shader.
8. Keep this document open for the next exercise.
24
Geographic Imager Tutorial Guide
Terrain Shader
Terrain Shader is used to style a DEM file or other image with z-values or to quickly create a gradient map
adjustment layer using predefined or user loaded color maps .
1. Continue working with Yukon Water.dem from the previous exercise or refer to the “Import from DEM” tutorial for
instructions on opening and configuring a DEM file.
2. On the Geographic Imager panel click the Terrain Shader button
. This opens the Terrain Shader dialog box.
3. Click the Colorization Schema check box to enable its frame options. The Apply Color Map option is chosen and
automatically applies the first color map (or the last color ramp used) in the list. If it’s different than what you see
in your dialog box, choose the World color map.
Note that the Background layer will also be affected since it is visible. The Create single layer option is checked
by default which creates one gradient map adjustment layer. Unchecking this option will create a gradient map
adjustment layer for each layer. The Use Continuous Color option is checked by default. It ensures the color ramp
has smooth transitions between colors instead of discrete colors.
4. Click the Import Color Map From File button in the Terrain Shader dialog box (third button to the right of the color
map). Choose the file Colour Ramp Examples.grd from the Tutorial Data folder.
5. Choose Elevation 3 from the Color Map drop-down list and click Import.
Geographic Imager Tutorial Guide
25
6. Click the Color Ramp drop-down list and choose Elevation 3. Then click the Edit Selected Color Map button to open
the Edit Color Map dialog box.
This dialog box shows how the elevation is mapped to the color ramp. Hover over the color ramp to see how the
elevation values correspond to the chosen color ramp.
7. Right-click the color swatch of the table entry for Color Stop 1 (at the top of the list) and click Edit Color Stop.
In the Select Color for Color Stop dialog box. Enter new color values of Red: 204, Green: 198, Blue; 181.
8. Click OK to close the color dialog box. Click OK again to close the Edit Color Map dialog box.
26
Geographic Imager Tutorial Guide
9. In the Terrain Shader dialog box, check the Apply Shaded Relief check box. Leave the angle at the default value of
45 degrees. Adjust the Intensity to 30 and click OK.
Your customized color ramp is applied to the DEM. In the Layers panel, notice that the original DEM (and
background) is maintained. The shaded relief and color map layer are at the top of the layers list.
10. Close all open documents without saving.
Reset Import DEM File Schema and Advanced Settings
Custom DEM schema settings and Advanced DEM Schema Settings are saved even after Adobe Photoshop is
closed. Both settings will be applied to each DEM image opened if values are not deleted.
1. Reopen the Yukon Water.dem file (or any DEM file).
2. In the Import DEM file dialog box, choose Auto-stretched from the Select Schema drop-down list.
3. Click the Advanced button to open the Advanced DEM Schema Settings dialog box.
4. Choose Display as background pixels from the Unique values drop-down list and select the 0.00 entry (or any
other entries). Click the Remove selected value(s) button and click OK to close the Advanced DEM Schema
Settings dialog box.
5. Click OK to close the Import DEM file dialog box to finish the import.
6. Close the document without saving.
Custom DEM schema settings and Advanced DEM Schema Settings are now reset.
Geographic Imager Tutorial Guide
27
Advanced Import
The Advanced Import function imports images and provides useful settings to change reference file, coordinate
system, color channel management, DEM schema, adjust image size and extents and even mosaic. It is also useful
for quickly cropping large sized images to a specific geographic area which may have initially required a long load
time. In this exercise, you’ll import two images of different formats, image sizes, and coordinate systems and then
mosaic them together.
1. In the Geographic Imager panel, click the Advanced Import button.
2. In the Advanced Import dialog box, click the Format drop-down list and choose GeoTIFF/BigTIFF/TIFF, and then
click Browse (you’ll be choosing a GeoTIFF).
3. Navigate to the Tutorial Data folder, choose boston-east.tif, then click Open. Click OK to close the message box.
The boston-east GeoTIFF image displays in the Import File list and shows that it has a Massachusetts Mainland
Zone coordinate system and an 800 x 800 pixel image dimension.
4. Click the Format drop-down list and choose ECW, then click Browse.
5. Navigate to the tutorial data folder, choose boston-west.ecw, then click Open.
The boston-west ECW image displays in the list and shows that it has no coordinate system and a 650 x 650 px
image dimension. You’ll use the Advanced Import options to make the images compatible so that they can be
used in a mosaic.
28
Geographic Imager Tutorial Guide
6. Make sure boston-west.ecw is highlighted in the file list. Below it, in the Source Coordinate System frame, click
the Same As check box.
Only boston-east.tif is available in the coordinate system drop-down list because it is the only other file
available in the file list. The coordinate system is updated to Massachusetts Mainland Zone in the file list for
boston-west.ecw. Next you’ll change the image dimensions for the GeoTIFF image by entering a resample value.
7. Make sure boston-east.tif is highlighted in the file list. Below it, in the Image Extents frame, click the Resample
button to open the Resample Image dialog box.
8. Change the width to 650 pixels. The Keep Aspect Ratio option ensures the height is also 650. Click OK.
The Dimensions column values update to reflect the resample size that you just entered.
The Image Extents frame also updates to reflect the resample size.
Geographic Imager Tutorial Guide
29
Lastly, you’ll setup the mosaic option so that the files can be mosaicked together.
9. At the bottom of the dialog box, click the Mosaic into Existing Document check box to enable its frame
elements. The boston-east.tif file is shown in the list and will be the destination for the mosaic.
10. Click OK to complete the Advanced Import process.
The two image formats are now mosaicked together to create one seamless image. This is a similar result to a
workflow that would have required you to open the images separately, adjust the coordinate system, change
the image size, and then create a mosaic.
In the Layers panel, notice that there is only one layer created from the two images. To maintain separate layers,
ensure the Keep source data on separate layers option is checked in the Advanced Import dialog box.
In the next exercise, you’ll use Advance Import to import DEM files.
11. Close all open documents without saving.
30
Geographic Imager Tutorial Guide
Advanced Import of DEM files
The Advanced Import function can also import DEM files and adjust its DEM schema settings. In this exercise you’ll
also specify coordinates to create a crop of the image.
1. In the Geographic Imager panel, click the Advanced Import button.
2. In the Advanced Import dialog box, click the Format drop-down list and choose DEM USGS/CDED ASCII Format,
then click Browse.
3. Navigate to the Tutorial Data\ Rocky Mountain 3D Landscape Data folder, choose Rocky Mountains.dem, then
click Open.
The Rocky Mountain DEM displays in the Import File list and shows that it has a NAD83 coordinate system
and an 1201 x 1201 pixel image dimension. Below the list, in the DEM Schema frame, the schema is displayed
(as Yukon Water). If the DEM Schema is not listed as Auto-stretched, click the Specify button and choose the
Auto-stretched schema.
4. In the Image Extents frame, click the Crop button. This opens the GeoCrop dialog box.
5. Make sure Geodetic is chosen in the Unit Type drop-down list and the coordinate format is Decimal degrees. In
the Top-left and Bottom-right Corner frames, enter the following values.
Top-left Corner:
Long: -121.180
Lat: 54.695
Bottom-right Corner:
Long: -121.047
Lat: 54.562
Geographic Imager Tutorial Guide
31
6. Click OK and then view the file list. The image dimensions are now 638 x 638 pixels (from 1201 x 1201 pixels)
according to the crop coordinates you just entered. The DEM Schema also changes to Crop auto-stretched to
indicate that not all of the values in the DEM are included in the schema.
You’ll save the DEM Schema so that it has a proper name and so you can see its range values.
7. In the DEM Schema frame, click the Specify button.
8. In the Import DEM File dialog box, click the green Create New Schema button. Enter Rocky Mountains Cropped as
the new schema name, then click OK.
The elevation range values for the cropped image are 930 meters (lowest) to 2310 meters (highest). Before the
crop, the range was 869 meters to 2534 meters. The crop cut some of the lower and upper range elevations.
9. Click OK to close the dialog box.
32
Geographic Imager Tutorial Guide
The DEM Schema name is updated in the file list and in the DEM Schema frame below. Its range values are also
shown. The image dimensions also updated below in the Image Extents frame.
10. Click OK to import the DEM.
11. Click the DEM tab and click the Calculate button to view more values about the schema range.
12. Close all open documents without saving.
Geographic Imager Tutorial Guide
33
Export Web Tiles
The Export Web Tiles feature generates image tiles that can be used for online map purposes. An HTML file is
created with the web tiles which consists of a web map with the tiles in already in place. Use the Web Tile Export
Options dialog box to adjust tile options.
1. In Adobe Photoshop, browse to the Tutorial Data folder and open boston-east.tif.
Before an image can be exported to web tiles, it must be in the WGS 84/Pseudo-Mercator coordinate system. The
Export Web Tiles feature will conveniently and temporarily transform the image from Massachusetts Mainland Zone
to WGS 84/Pseudo-Mercator so that it is compatible.
2. From the Geographic Imager panel, click the Export Web Tiles button.
3. Click Transform the image and proceed with the export.
4. In the Web Tile Export Options dialog box, click Browse and rename the dataset name to index.html. Choose an
image format to PNG and choose a World reference file. In the Zoom Level Options frame, choose a Max Zoom of
Level 17 - 1.19 meters/pixel and change the number of zoom levels to 3. A total of 76 web tiles will be created. Note
that the Min Zoom is Level 15.
34
Geographic Imager Tutorial Guide
5. Click OK to begin the export process.
6. After the web tile export completes, navigate to the export folder you specified and double-click the index.html
file to open it in a web browser.
In the export folder, several new folders were created (Z15, Z16, and Z17). These folders hold the PNG images that
make up the web tiles and represent the three zoom levels you chose. Also included are TFW world reference files
because you chose to create them during export. Creating a reference file is not required, but may be useful if the
web tiles were to be repurposed.
7. Close all open documents without saving.
Geographic Imager Tutorial Guide
35
Using Actions with Geographic Imager
This exercise demonstrates how to automate Geographic Imager by recording an action that opens an image and
transforms the coordinate system to WGS 84. See Chapter 10 - Automating Geographic Imager for more details.
Note: Actions should only be used on the computer it was created on. Actions are not cross platform and use
absolute paths.
1. In the Adobe Photoshop menu, choose Window > Actions to open the Actions panel.
2. In the Action panel option menu (top right corner), choose New Set. Rename it Open - Transform WGS 84 and click OK.
This creates an action set folder to store the action.
3. With the new Open - Transform WGS 84 set folder selected, choose New Action from the Action panel option
menu. Rename the action to EuropeTL to WGS 84.
A function key and colour for the action can be set, however, it is not needed for this exercise.
4. Click Record to create the action.
Notice that the red Begin recording button in the Actions panel is enabled. From this point on, all operations will
be recorded to the action until it is stopped.
5. In the Adobe Photoshop menu, choose File > Open. Browse to the Tutorial Data folder containing the tutorial
images and open EuropeTL.tif.
6. Choose File > Automate > Geographic Imager: Transform. In the Transform dialog box, perform a coordinate
system transformation to WGS 84 (Geodetic > World).
7. In the Action panel, click the Stop Playing/Recording button. Notice the action steps are recorded beneath the
action name.
8. To play back the action, close the image without saving, select the EuropeTL to WGS 84 action and click the Play
button in the action panel.
Congratulations, you have completed the Geographic Imager Tutorial Guide. Move onto the Adobe Photoshop
exercises in the next section. Also see the Geographic Imager User Guide for detailed info about features.
36
Geographic Imager Tutorial Guide
Adobe Photoshop Tutorial Exercises
The following tutorial exercises use existing Adobe Photoshop functions to manipulate spatial imagery to create
affects such as shaded relief, colour ramps, 3D elevation models, false-colour composite and pan sharpened
images. In addition, learn how to record measurements with the Ruler Tool and resample and sharpen images.
These tutorial exercises differ from the previous set of exercises because they mainly involve the use of Adobe
Photoshop tools, functions and filters. Geographic Imager allows non-native formats such as DEM files, MrSID,
ECW and JPEG 2000 to be imported and used with an Adobe Photoshop environment while streamlining the
cartographic work flow.
These exercises are only basic examples of what Geographic Imager for Adobe Photoshop is capable of doing.
Combined with creative uses of both sets of tools, a wide range of image manipulation techniques are achievable.
Content
Using Actions with Geographic Imager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Create a 3D Representation with a Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
The Ruler Tool and Measure Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Create a False-Colour Composite with Multiple Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Create a False-Colour Composite with Channel Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Pan Sharpen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Resample and Sharpen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Geographic Imager Tutorial Guide
37
Create a 3D Representation with a Script
This exercise demonstrates how to use a custom script with Geographic Imager to open a DEM, overlay it with an
image and to create a 3D effect. See Chapter 12 - Automating Geographic Imager for more details.
1. In Adobe Photoshop, click File > Scripts > Browse. Browse to the Sample Scripts folder, click
3D Overlay Script.jsx, then click Load.
No image are open, so you are prompted to open a DEM. This script also works if a DEM is already open.
2. Click Yes.
3. Browse to the Rocky Mountain 3D Landscape Data folder, click Rocky Mountains.dem, then click OK.
The Import DEM File dialog box appears.
4. Choose the Auto-stretched schema and click OK.
This script allows you to choose a image to overlay the DEM. If no image is chosen, Terrain Shader can be used
to create a color map for it. You’ll choose the accompanying tutorial GeoTIFF image to overlay.
5. Click Yes.
38
Geographic Imager Tutorial Guide
6. Browse to the Rocky Mountain 3D Landscape Data folder, click Rocky Mountains.tif, then click OK.
A 3D operation is performed to the Rocky Mountains DEM and the Rocky Mountains GeoTIFF is overlayed on
top of it. This image is still considered a dynamic object in Adobe Photoshop and it can be controlled with the
3D panel (Window > 3D) and the Object Rotate Tool and Camera Rotate Tool in the Tools toolbar.
The 3D panel has options to change lighting settings (such as opacity, light source, intensity) and render
settings (such as 3D options, cross section, quality). The vertical exaggeration can be adjusted with the Object
Rotate Tool and the green axis adjustment.
Note: When creating a 3D representation, georeferencing is not maintained.
Geographic Imager Tutorial Guide
39
The Ruler Tool and Measure Tab
Analysis tools can be used to record and export measurements with georeferenced images. This exercise uses the
Adobe Photoshop Ruler tool in combination with the Geographic Imager Measure tab located in the panel.
1. In Adobe Photoshop, choose File > Open and browse to the Landsat 7 Multispectral folder and open
Band 8 (Panchromatic), 15 meters.tif.
This is an image of downtown Toronto circa 2004. The projected coordinate system is NAD 83 UTM Zone 17N in
meters. The Geographic Imager panel displays the pixel size. A precise measurement is dependent on the pixel
size. For this example, 1 pixel is equal to 15 x 15 meters and provides a moderately accurate measurement.
Note: Non-square pixels prevent the recording of correct measurements when using measurement tools. This can
be rectified by using the Geographic Imager Transform function and changing the Pixel Options to keep
pixels square.
2. Before measuring, choose Window > Measurement Log to open the Measurement Log panel. The panel appears
either as floating or docked at the bottom of the screen. In the panel options menu, choose Set Measurement
Scale > Custom.
3. In the Measurement Scale dialog box. Set the Logical Length to 15. Type the Logical Units as meters.
Note: Up to four decimal places can be entered in the custom field to provide enough accuracy for all images.
The Logical Units box stores what unit the pixel size is in. A custom preset measurement scale is useful when
using images with the same pixel size.
4. Click OK to close the dialog box.
40
Geographic Imager Tutorial Guide
5. In the Adobe Photoshop Tools panel, select the Ruler Tool
. (If it isn’t visible, click and hold the Eyedropper
Tool button to display the flyout menu, then choose the Ruler Tool).
6. Take a measurement of a section of Toronto. As shown below, click anywhere on the map and drag the Ruler
Tool. Click again to complete the measurement. A measurement line is drawn on the image.
7. In the Geographic Imager panel, click the Ruler tab. Click the Update button.
The measurement is shown in page (pixels) and cartesian units (meters) for Segment L1. Next you’ll use the
Ruler Tool to measure another segment.
8. Click the Ruler Tool again. Hold the Alt (Win) or Option (Mac) key and hover over the end of the first segment.
The icon changes to signify that an additional angled segment can be drawn. Click and draw a measurement
that is 90-degrees west of the first segment.
Geographic Imager Tutorial Guide
41
9. In the Geographic Imager panel, click the Update button again (in the Ruler tab).
A second segment value is updated in the panel. However, this does not record or save your measured distance.
You’ll use the Measurement Log panel to record it.
10. In the Measurement Log panel, click Record Measurements.
For the above example, the distance recorded is approximately 2800 meters (Length column). Your results may
vary depending on how long of a ruler line you drew. Three measurements are recorded: Total length, segment
1 and segment 2.
All measurements can be exported to a tab delimited Unicode text file (select desired rows and choose Export
Selected button in the Measurement Log panel options menu).
11. In the Measurement Log panel, select the three measurements. Click the Measurement Log panel options menu
and click Export Selected. Rename the output file to measurements.txt and save it to your Desktop.
12. Open the measurements.txt file to see what the values look like when exported.
13. Close all documents without saving.
Note: Remember the resolution of the image will reflect how accurate the measurements will be. Analysis tools can
not be used with non-square pixels because each side has a different length.
42
Geographic Imager Tutorial Guide
Create a False-Colour Composite with Multiple Images
Another powerful remote sensing tool in Adobe Photoshop is the ability to create a false-colour composite image.
Multispectral images contain information inside and outside the visible electromagnetic spectrum. To use this
information, the wavelengths outside the visible spectrum need to be reassigned to the visible spectrum so that it
is visible to the human eye. This tutorial will create a false-colour composite of downtown Toronto and surrounding
suburban areas.
Often multispectral satellite images will consist of several grayscale images, with each image containing one of the
wavelengths or bands of the electromagnetic spectrum. These images need to be combined into one image. The
Adobe Photoshop function called Merge Channels merges images to create false-colour or true-colour composites.
You may easily identify distinct features by their unique spectral signature.
1. In Adobe Photoshop, browse to the Landsat 7 Multispectral folder and open the following images:
•
•
•
Band 2 (Green), 30 meters.tif
Band 3 (Red), 30 meters.tif
Band 4 (Near Infrared), 30 meters.tif
Note: When creating false-colour composites, images must be of the same image resolution and have the same
spatial extents. If the images need to be cropped, it is recommended to use the Geographic Imager GeoCrop
function to assure that the extents of the images remain consistent.
2. From the Windows menu, choose Channels to open the Channels panel.
3. In any of the active document windows, click Merge Channels from the Channels panel options menu.
4. In the Merge Channels dialog box, choose RGB Color in the Mode drop-down list and ensure there are 3 channels.
Click OK.
Geographic Imager Tutorial Guide
43
5. In the Merge RGB Channels dialog box specify the following channels:
•
•
•
Red: Band 4 (Near Infrared), 30 meters.tif
Green: Band 3 (Red), 30 meters.tif
Blue: Band 2 (Green), 30 meters.tif
6. Click OK to complete the merge.
Note: A reference file called Untitled-x.tfw (the x value may change depending on if you have other reference files
named something similar) is created in the default reference format specified in the Geographic Imager
Preferences dialog box.
A false-colour composite image with georeferencing is created. The band combination chosen makes vegetation
appear in shades of red because vegetation reflects a lot of near infrared light. The brighter the red, the healthier
the vegetation. Urban areas appear blue-grey. The bright red areas at the top of the image belong to the prestigious
Rosedale Golf Club.
7. Close all open documents without saving.
44
Geographic Imager Tutorial Guide
More about Landsat 7 band combinations
R,G,B
Description
3,2,1
The “nature colour” combination. It provides the most water penetration.
4,3,2
Standard “false-colour” combination. Vegetation shows in red.
7,4,2
The “nature-like” combination. Sand, soil and minerals show in multitude of colour. Fires would appear in
red. It provides clear imagery in desert region.
7,5,3
The “nature-like” combination. Sand, soil and minerals appear in variety of colour.
5,4,1
Good for agricultural studies. Healthy vegetation shows in bright green colour.
7,5,4
Provides best atmospheric penetration. Vegetation shows in blue. Useful for geological study.
7,3,1
Rocks may appear in variety of colour. Good for the geological study.
Note: Some multispectral images may be provided as a single image that stores extra channels (called alpha channels in Adobe Photoshop). To create false-colour composites from these images in Adobe Photoshop, the
channels must first be split into single gray scale images (Channels panel option menu > Split Channels). Then
channels can be merged and reordered as described above.
Create a False-Colour Composite with Channel Management
Creating a false-colour composite image with an image that contains an extra band of information (alpha channel)
is best done with Geographic Imager Channel Management.
1. In Adobe Photoshop, browse to the Landsat 7 Multispectral folder and open All bands.tif.
This image is similar to the previous exercise, except that it has all the bands (channels) already merged into it.
You’ll use Geographic Imager Channel Management to create a false-colour composite.
Geographic Imager Tutorial Guide
45
2. From the Geographic Imager panel, click the Channel Management button.
The current Color Mode is Grayscale Color which explains why the image is displayed as such.
3. Click the Color Mode drop-down list and choose RGB Color.
The Gray Band is assigned a channel role of Red, Band 2 is assigned Greend, and Band 3 is assigned Blue. You’ll
change the visibility of the Gray Band and reassign the channel roles for bands 2, 3, and 4 to create the correct
false-colour composite appearance.
46
Geographic Imager Tutorial Guide
4. Click the Visibility check box for Gray Band to disable it. Click the Visibility check box for Band 4 to enable it.
The new channel roles will follow the ones used in the previous exercise (RGB - 4, 3, 2).
5. Click the Band 4 Channel Role (it is set as Alpha 1) and choose Red in the drop-down list. Change the Band 3
Channel Role to Green. The Band 2 Channel Role should automatically update to Blue.
6. Click OK to confirm the reassignment of channels.
A false-colour composite image using Channel Management is created. These changes are reflected in the
Geographic Imager Channels panel.
7. Close all open documents without saving.
Geographic Imager Tutorial Guide
47
Pan Sharpen
Another useful tool Adobe Photoshop provides is the ability to intelligently resample images. Pan sharpening (short
for panchromatic sharpening) the use of a single band to increase the spatial resolution of a multispectral image. A
multispectral image contains a higher spectral resolution of a panchromatic image, while often a panchromatic image will have a higher spatial resolution than of a multispectral image. A pan sharpened image represents the best
of both worlds which is essentially a sensor fusion that gives a multispectral image higher spatial resolution.
1. In Adobe Photoshop, browse to the Landsat 7 Multispectral folder and open the following images:
•
•
•
•
Band 8 (Panchromatic), 15 meters.tif
Band 1 (Blue-green), 30 meters.tif
Band 2 (Green), 30 meters.tif
Band 3 (Red), 30 meters.tif
In this exercise, the panchromatic image will be combined with a multispectral image in true colour, however, any
false-colour composite combination can be used.
2. From the Window menu, choose Channels to open the Channels panel.
3. In any 30 meter resolution active document window (Band 1, 2 or 3), click Merge Channels from the Channels
panel options menu.
Note: If Band 8 is chosen, Merge Channels will be disabled.
4. In the Merge Channels dialog box, select RGB Color in the Mode drop-down list and click OK.
5. In the Merge RGB Channels dialog box specify the following channels:
•
•
•
Red: Band 3 (Red), 30 meters.tif
Green: Band 2 (Green), 30 meters.tif
Blue: Band 1 (Blue-green), 30 meters.tif
6. Click OK to complete the merge.
48
Geographic Imager Tutorial Guide
Since the merged image is at 30 meter resolution, it is necessary to resample it to match the resolution of the
panchromatic image (15 meter resolution).
7. With the merged document window active, choose Image > Image Size.
8. Ensure Constrain Proportions and Resample Image check boxes are checked. Choose Bicubic (best for smooth
gradients) as the resampling method.
9. In the Pixel Dimensions frame, select Percent from the units drop-down list.
10. Enter 200 in the width dimension and click OK to complete image scaling.
11. From the Image menu, choose Mode > Lab Color.
Geographic Imager Tutorial Guide
49
12. In the Channels panel options menu, click Split Channels.
The merged image is split into three images: Lightness, a and b.
The split images have a “_Lightness”, “_a”, or ,”_b” added to the end of the document name. The a and b channels
carry green-red and blue-yellow information respectively. Our process is to substitute the panchromatic image
for the Lightness channel.
The following step involves some trial and error. The intent is to make the image brightness and contrast match the
Lightness channel as much as possible. Ignore areas of water or vegetation and concentrate on roads and buildings. Often panchromatic images contain data that extend into the infrared, therefore vegetation and areas of water
appear differently. The higher resolution of the panchromatic image, the more contrast it will appear to have.
Note: Ignore vegetation and areas of water because panchromatic images often contain near infrared data.
13. Make Band 8 (panchromatic), 15 meters.tif active and create a Brightness/Contrast adjustment layer. Choose Layer >
New Adjustments Layer > Brightness/Contrast. Click OK to accept the default name and settings.
14. In the Brightness/Contrast settings (Adjustment panel), adjust Brightness to +100 and Contrast to +35.
15. Create a second adjustment layer. Choose Layer > New Adjustments Layer > Levels. Click OK to accept the default
name and settings.
50
Geographic Imager Tutorial Guide
16. In the Levels settings (Adjustment panel), change the midtone input level to 0.9 and the highlight input level to
230.
17. To properly merge channels, the layers need to be flattened first. Choose Layer > Flatten Image.
18. In the Channels panel options menu, click Merge Channels. In the Merge Channels dialog box, select Lab Color in the
Mode drop-down list and click OK.
19. In the Merge Lab Channels dialog box specify the following channels:
•
•
•
Lightness: Band 8 (Panchromatic), 15 meters.tif
a: Untitled-1_a
b: Untitled-1_b
Note: The Untitled documents were created from splitting the channels in step 14. Untitled documents may not be
appended with the number 1, however, be sure that the final character corresponds to the channel e.g. a =
“Untitled-4_a”.
20. Click OK to complete the merge.
Geographic Imager Tutorial Guide
51
21. Choose Mode > RGB to convert the image back to RGB mode.
22. Leave the document open for the next exercise.
Note: This exercise is a guide to enhance images for display or printing purposes, this method involves subjective judgment to pixel colour adjustments and should not be used for scientific purposes. The colours of
the pan-sharpened image will look different from the original RGB image because panchromatic data (from
Landsat 7) extend into the infrared, most notably vegetation and areas of water.
52
Geographic Imager Tutorial Guide
Resample and Sharpen
Adobe Photoshop sharpen filters can increase the detail of the image. The Sharpen filter menu has a variety of
sharpening tools. These tools also involve some trial and error to achieve enough sharpening without overdoing it.
Two sharpening filters are explained below.
The Unsharp Mask
This filter sharpens an image by increasing contrast along the edges of an image. It locates pixels that differ in value
from the surrounding pixels, this option can be modified by changing the threshold. The radius of the region to
which each pixel is compared is also an option that can be modified.
Smart Sharpen
This filter has more advanced controls not available in the Unsharp Mask filter. This filter will allow control over the
amount of sharpening that occurs in shadow and highlight areas. The document should be viewed at 100% to get
an accurate view of the sharpening.
•
•
•
•
•
Amount: Sets the amount of sharpening. A higher value increases the contrast between edge pixels, giving the
appearance of greater sharpness.
Radius: Determines the number of pixels surrounding the edge pixels affected by the sharpening. The greater
the radius value, the wider the edge effects and the more obvious the sharpening.
Remove: Sets the sharpening algorithm used to sharpen the image. Gaussian Blur is the method used by the
Unsharp Mask filter. Lens Blur detects the edges and detail in an image, and provides finer sharpening of detail
and reduced sharpening halos. Motion Blur attempts to reduce the effects of blur due to camera or subject
movement. Set the Angle control if you choose Motion Blur.
Angle: Sets the direction of motion for the Motion Blur option of the Remove control.
More Accurate: Processes the file more slowly for a more accurate removal of blurring.
In the Smart Sharpen dialog box, click the Advanced option to display the Shadow and Highlight tabs. Adjust sharpening of dark and light areas using these tabs. If the dark or light sharpening halos appear too strong, reduce them
with these controls, which are only available for 8‑bits and 16‑bits-per-channel images:
•
•
•
Fade Amount: Adjusts the amount of sharpening in the highlights or shadows.
Tonal Width: Controls the range of tones in the shadows or highlights that are modified. Move the slider to the
left or right to decrease or increase the Tonal Width value. Smaller values restrict the adjustments to only the
darker regions for shadow correction and only the lighter regions for highlight correction.
Radius: Controls the size of the area around each pixel that is used to determine whether a pixel is in the
shadows or highlights. Moving the slider to the left specifies a smaller area, and moving it to the right specifies
a larger area.
Geographic Imager Tutorial Guide
53
1. With the image still open from the previous exercise, choose Filter > Sharpen > Smart Sharpen.
2. Set the following parameters in the Smart Sharpen dialog box:
•
•
•
•
Set the Amount to 15%
Set the Radius to 2.0 pixels
Set Remove to Lens Blur
Check the More Accurate check box
3. Click OK.
Features appear to have more detail when compared to the image prior to sharpening. Again, this will involve some
trial and error if the results are not satisfactory, experiment with settings if more sharpening is needed.
Congratulations, you have completed the Adobe Photoshop Tutorial Exercises. For more in-depth information on
Geographic Imager tools and features, see the Geographic Imager User Guide and also online at www.avenza.com.
54
Geographic Imager Tutorial Guide
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising