Creating 3D Visualizations

Creating
3D Visualizations
Introduction
Who cares about
3D Visualizations?
A picture is worth a
thousand words, and a
single picture may turn the
tide in your favor when
dealing with the public, those
providing funding, or
cooperators.
Educating others is a key component
of successful weed management
programs. Pictures can be the most
motivating components of educational
efforts.
This document provides guidelines for
creating 3-dimensional (3D)
visualizations, including static
depictions and animated fly-bys.
These visualizations are helpful
because they:
•
•
•
Present information in a format
that most people understand
(three dimensions vs. flat maps)
Allow interactivity with the
audience—various viewing
angles, zooming in/out, etc.
Provide a “wow factor” that
should not be overlooked!
QUICK LOOK
Objective:
This document will help you or your
GIS coordinator create a 3D
visualization of a weed infestation,
watershed, or other area using
ArcScene.
Data Requirements:
• Digital image, DOQ, map, or photo
• DEM
Software Requirements:
• ArcGIS with 3D Analyst extension
Cost:
Low
High
Moderate
High
Expertise:
Low
Salt Cedar—Natural color
3D visualization of a
saltcedar infested waterway
in western Colorado,
created from high-resolution
aerial imagery. Locations of
salt cedar are shown in light
purple.
Moderate
Major Steps
1. Define the objective and assemble
the data.
2. Load the data and set data frame parameters.
3. Set digital elevation model (DEM) and image parameters.
4. Inspect and fly through the 3D image visualization.
5. Export views and record fly-through movies.
Define the Objective and Assemble the Data
AUTHOR
Randy M. Hamilton
Remote Sensing
Applications Center,
Salt Lake City, UT
Before creating
a 3D visualization, carefully define your objective. Clearly
Flowers
& Bracts
defined objectives will help you assemble the correct data and create a
visualization that will effectively convey your message. For example, you may
wish to fly through a riparian area to show the size or change in a weed
infestation, or visualize where treatments could have the greatest impact.
Alternatively, you may wish to show adjacent watersheds and how targeted
suppression efforts in one could prevent a weed from spreading into another.
A Weed Manager’s Guide to Remote Sensing and GIS — Educating the Public
Creating 3D Visualizations
Data
Two data sets are required to create a 3D visualization—a DEM and a raster
image such as:
•
•
•
•
Satellite imagery (e.g., from Landsat, SPOT, IKONOS, or QuickBird)
Digital aerial photos (e.g., digital camera imagery, scanned photos)
Thematic grids/layers (e.g., existing vegetation maps)
Digital maps (e.g., digital raster graphics [DRGs])
However, a variety of optional datasets may enhance the message of the
visualization. These include:
•
•
Vector layers (e.g., shapefiles of existing weeds, treatments, roads, etc.)
Annotations (e.g., text, lines, points)
IMPORTANT
Before starting, make sure
you have ArcGIS with the
3D Analyst extension
installed on your computer.
The 3D Analyst extension
adds ArcScene, the 3D
viewing application
required to create 3D
visualizations
Special Considerations
As you assemble your datasets, be sure that:
1. The extent of the DEM covers your entire project area.
2. Your image is ortho-corrected.
3. All datasets have the same projection and coordinate system.
Load the Data and Set Data Frame Parameters
The following steps will guide you through loading your data and setting the
data frame parameters:
TIP
Vertical Exaggeration is
typically used to emphasize
vertical topography,
particularly when there is
little vertical change in the
terrain compared to the
horizontal extent. However,
a value less than 1 will
flatten terrain with extreme
vertical change. Try several
different values to achieve
the desired look.
TIP
Background Color is the
color displayed beyond the
extent of the displayed
image. Black can simulate
nighttime while blues can
simulate a daytime sky.
1. Launch ArcScene from the Start menu (Start | Programs | ArcGIS |
ArcScene)
2. Click the Add Data button from ArcScene’s Standard toolbar.
3. Navigate to and select your DEM.
4. Click Add to load the DEM into ArcScene’s Table of Contents.
5. Click the Add Data button from ArcScene’s Standard toolbar.
6. Pubescence
Navigate to and select your image.
Plant
7. Click Add to load the
image into ArcScene’s
Table of Contents.
8. Double-click on Scene
Layers in the Table of
Contents to open the
Scene Properties dialog.
9. Select the General tab
from the Scene Properties
dialog. Set the following
parameters:
• Vertical
Figure 1—Suggested vertical exaggeration and
Exaggeration: 2
background color.
(figure 1)
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Creating 3D Visualizations
•
TIP
Illumination — The
illumination tab allows you
to set the position of the
lighting source (sun), which
determines the shadowing
imposed on the imagery.
The azimuth defines the
compass location of the
lighting source while the
altitude is the height (in
degrees) of the lighting
source above the horizon.
Contrast controls the
amount of shading applied
to the image.
TIP
Offset —The offset
parameter in the Base
Heights tab allows you to
offset a layer above or
below other layers in the
scene. When the DEM and
image are displayed
simultaneously, an offset of
20 helps ensure that the
image appears on top of
the DEM. For vector files,
an offset will ensure that
the points, lines, or
polygons are visible on the
image.
TIP
Quality enhancement for
raster images —The
higher the rendering
quality, the better the
quality of the displayed, but
the longer it will take to
redraw.
Background Color:
Black
10. Select the Illumination tab
from the Scene Properties
dialog. Set the following
parameters:
• Azimuth: 315
• Altitude: 30
• Contrast: 50 (figure 2)
Set DEM and Image
Parameters
Figure 2—Suggested illumination settings.
1. Double-click your DEM in
the Table of Contents.
2. Select the Base Heights tab from the Layer Properties dialog. Set the
following parameters:
• Enable the Obtain heights for a layer from surface radio button
and ensure that the associated directory identifies the correct path to
your DEM.
• Select Apply, and then click OK to close the dialog.
3. Uncheck the check box associated with your DEM in the Table of
Contents—this will turn off the display of your DEM in the Data
View.
4. Double-click your image in the Table of Contents.
5. Select the Base Heights tab from the Layer Properties dialog. Set the
following parameters:
• Enable the Obtain heights for a layer from surface radio button
and set the associated directory to your DEM (click the associated
Yellow Folder button, navigate to the location of your DEM, select
your DEM, and click Add).
• Set Offset to 20.
6. Select the Symbology tab from the Layer Properties dialog. Set the
following parameter:
• Enable the Display Background Value, click the pulldown arrow
from the associated Color Box, and select No Color from Color
Palette (figure 3).
7. Select the Rendering tab from the Layer Properties dialog. Set the
following parameters:
• Adjust Quality
enhancement for
raster images to
medium-high (adjust
Figure 3—Suggested color setting for
slider bar as necessary).
Display Background Value is “No Color,”
8. Click Apply, and then OK
which allows the background color set in
to close the dialog.
the Scene Properties dialog to show in
these areas.
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Creating 3D Visualizations
Inspect and Fly Through the 3D Visualization
TIP
Navigate tool—This tool
can accomplish nearly
every action of the other
navigation tools using a
combination of mouse
clicks and keystrokes. To
find out how, click the
help
button in
ArcScene, then click the
Navigate tool button.
The 3D visualization is now ready for inspection. Using ArcScene’s navigation
tools (figure 4), you can specify a target location to view and the location of the
observer. Alternatively, you can pan and zoom in all three dimensions to
explore the scene. Or, if you prefer a bird’s eye view, you can fly through the
scene using the fly tool. Explore the scene using these tools.
Navigate—used to alter the
scene’s perspective
Fly—left click to fly forward, right
click to fly backwards
Zoom In—click to zoom in, or click
and drag to zoom in to the region
within the box
Zoom Out—click or click and drag
to zoom out
Zoom In/Out—click and hold,
then move the mouse toward or
away from you to zoom in or out
Narrow Field of View—zooms in
by narrowing the field of view
Center on Target—click to center
the view on a target position
Widen Field of View—zooms out
by expanding the field of view
Zoom to Target—click to zoom to
a particular location
Zoom to Full Extent—zooms to
the full extent of your data
Set Observer—click to set the
location of the observer
Pan—click, hold, and drag to pan
the scene to the left, right, up, or
down
Figure 4—ArcScene’s navigation tools, located on the Tools toolbar, permit easy
navigation throughout your 3D scene.
You may want to experiment by changing the suggested data frame, DEM, and
image parameters set in previous sections. Changing parameters will modify
the overall look of the 3D scene.
Export Views of 3D Visualizations
ArcScene can be used interactively during a presentation to build public
awareness, or awareness among cooperators or funding entities. Alternatively,
single views of the scene can be exported for printing or for use in
presentations. In addition, fly-through movies can be recorded for future use.
This section provides guidelines for creating these products.
Single views of the scene can be exported from ArcScene by following these
steps:
1. Select a view that will convey the message you wish to communicate.
2. Adjust the height and width of the scene window to the extent of the
view you wish to export.
3. From ArcScene’s File menu, select Export Scene, then 2D.
4. In the Scene Export dialog:
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Creating 3D Visualizations
•
TIP
Export Resolution—For
printing, the resolution
should be at least 300 dpi;
for presentations, a
resolution of 72 or 96 dpi is
adequate.
Select a file type for export from the drop-down list adjacent to
Save as type.
• Click the Options button and set the output resolution and other
parameters specific to the file type you selected. Click OK when
finished.
• Navigate to the directory you want to export the file to.
• Enter a name for the file you will export.
• Click Export.
5. View the new file to ensure that it exported correctly (figure 5).
Figure 5—Color infrared 3D visualization of a saltcedar-infested waterway in western
Colorado, created from IKONOS satellite imagery. On this image, saltcedar is the
coarsely-textured, darker red vegetation.
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Creating 3D Visualizations
Record and Export Fly-Through Movies
TIPS
To facilitate smooth
navigation while defining
the camera track, reduce
the Quality enhancement
for raster images on the
Rendering tab of your
image’s Layer properties
dialog. When ready to
record the movie, increase
the Quality enhancement
for raster images to high.
This will create a high
resolution movie.
Fly-through movies showing weed infestations from imagery, locations of
mapped weeds, areas having high probability for invasion, or watersheds can
be powerful educational tools to illustrate the location and severity of weed
infestations, pathways of spread, and locations where intervention could make
the greatest impact. Flying through a ranger district, for example, with district
boundaries and existing weed polygons displayed over the imagery provides
perspective unobtainable in any other way.
There are several ways to create fly-through movies in ArcScene. The main
difference among the methods is the way the path of travel is defined. Two
common methods include recording the flight path (camera track) as you fly
through the scene, and defining the path from a linear feature in a shapefile.
Guidelines for creating fly-through movies using these two methods follow.
Creating Fly-Through Movies Using the Fly Tool
The following steps will guide you through the process of creating a flythrough movie from a camera track recorded while flying through the scene:
DEFINITIONS
Keyframe: Keyframes can
be thought of as points that
define the camera track. In
other words, the camera
track passes through the
set of keyframes.
Track: A track is the path
along which the “camera”
travels in the virtual 3D
environment. The track is a
linear interpolation through
the keyframes.
1. Turn on the Animation toolbar, if not already visible, from the View
menu (View | Toolbars | Animation).
2. On the Animation toolbar, click the Open Animation Controls
button
to open the Animation Controls dialog.
3. Navigate to a starting location using the navigation tools.
4. Click the Fly button on the Tools toolbar.
5. Click the Record button
6. Using the Fly tool, fly through the scene to define the camera track.
7. When finished, press the ESC key on your keyboard.
8. Click the Stop button
TIPS—FLYING
Speed—When flying using
the Fly tool, you can fine
tune your speed by
pressing the up and down
arrow keys between mouse
clicks. Altitude—You can
maintain a constant altitude
while flying by pressing and
holding the SHIFT key.
While holding down the
SHIFT key, move your
mouse up or down to look,
but not travel, in these
directions.
on the Animation Controls toolbar.
on the Animation Controls toolbar to
finalize and record the track.
9. To review the fly-through that follows the recorded track, click the Play
button
on the Animation Controls toolbar.
10. To modify the camera track, click Animation on the Animation
Controls toolbar, then select Animation Manager.
• Select the Keyframes tab to display the individual keyframes that
define the track. The keyframes are numbered consecutively from
the beginning to the end of the track.
• To see the view at a particular keyframe, select it by clicking on its
row, then click the View button.
• Unwanted keyframes, such as those corresponding to rough
navigation at the beginning of the track, can be removed by
selecting the corresponding rows and clicking Remove.
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Creating 3D Visualizations
•
CAUTION
While exporting a movie,
do NOT open or move any
windows in front of the
scene window, as these
windows will be recorded in
the movie.
ERROR MESSAGE?
When exporting a movie, if
an error window pops up
stating that “The AVI export
failed…,” decrease the size
of your scene window and
try again. This error
generally occurs when the
scene window is too large,
causing a movie file to be
created that is too large for
the software to handle—the
larger the scene window
on your screen, the larger
the video file.
TIP—PATHS
Simple paths with few
vertices typically produce
the best fly-throughs.
Other variables such as altitude, inclination, roll, and view angle can
be adjusted manually for individual keyframes by selecting the
appropriate cell and entering a new value.
11. When satisfied with the fly-through track, adjust the horizontal and
vertical dimensions of the scene window to the desired size and
extent—the movie you record will have these exact dimensions.
12. Click Animation on the Animation toolbar and select Export to
video…
13. In the Scene Video Export dialog, navigate to the directory where you
want to save the movie, enter a file name, then click Export.
14. View the exported movie to ensure that it recorded properly.
Creating Fly-Through Movies Using a Path from a Shapefile
The following steps will guide you through the process of creating a camera
track for a fly-through movie using a feature from a polyline shapefile:
1. In ArcMap (not ArcScene), add your image or map to the active data
frame.
2. Add a polyline shapefile to the data frame (you may wish to create a
new shapefile—a feature will be created in this shapefile to define the
camera track).
3. Use ArcMap’s editing tools to create a path for the camera to follow
over the imagery or map. Save the edits to the shapefile.
4. In ArcScene, Add the shapefile, containing the path you created, to the
scene where your imagery is displayed.
5. Double-click the shapefile in the Table of Contents.
6. Select the Base Heights tab from the Layer Properties dialog. Set the
following parameters:
• Enable the Obtain heights for a layer from surface radio button
and ensure that the associated directory identifies the correct path to
your DEM.
• Set Offset to 40.
7. Click Apply, and then OK to close the dialog.
8. With the polyline path now visible above the imagery, select the Select
Features button
on the Tools toolbar, then click on the path to
select it.
9. Click Animation on the Animation Controls toolbar, then select
Camera Flyby from Path... Do the following:
• Enable the Selected line feature radio button.
• Enter 100 in the Vertical offset box.
• Enable the Move both observer and target along path (flyby)
radio button.
• Click the Orientation Settings… button.
• Under Roll settings, enable the Calculate from path radio button
• Enter a scale factor of 0.5.
• Click OK to close the Orientation settings dialog.
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Creating 3D Visualizations
•
TIP—PERSPECTIVE
Modify the view from the
plane by changing the
Azimuth and Inclination in
the Orientation settings
dialog. A positive or
negative value for Use
path azimuth + rotates the
view to the right or left. A
positive or negative value
for Use path inclination +
rotates the view up or
down.
Click Import to convert the path to a camera track with associated
keyframes.
10. On the Animation toolbar, click the Open Animation Controls
button
11. Click the play button
on the Animation Controls toolbar to
view the fly-through.
12. If the elevation and roll of the fly-through are not satisfactory, repeat
steps 9 through 11 and experiment with different values for the Vertical
offset and roll scale factor.
13. Individual keyframes can be modified by following step 10 in the
“Creating Fly-Through Movies Using the Fly Tool” section.
14. When satisfied with the fly-through track, adjust the horizontal and
vertical dimensions of the scene window to the desired size and
extent—the movie you record will have these exact dimensions.
15. Click Animation on the Animation toolbar and select Export to
video…
16. In the Scene Video Export dialog, navigate to the directory where you
want to save the movie, enter a file name, then click Export.
17. View the exported movie to ensure that it recorded properly.
TIP—FLY SPEED
To change the flight speed,
click the Options button in
the Animation Controls
dialog (if Play options are
not visible). Under Play
options, increase or
decrease the Duration
time to change the flight
speed.
ASSISTANCE?
For more information or
assistance, please contact
Forest Service
Remote Sensing
Applications Center
(RSAC)
2222 S. 2300 W.
Salt Lake City, UT 84119
(801) 975-3750
RSAC Intranet
http://fsweb.rsac.fs.fed.us
RSAC Internet
http://www.fs.fed.us/eng/rsac
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