How to Do a Geo-Fly Through

Internal Document Only -- Watch Us Work

If you have DEM (Digital Elevation Model) data and image and/or vector data, you can overlay the image and/or vector on top of the DEM. You can then fly through the data and make a movie of your flight path using ERDAS Imagine's VirtualGIS Module.

Before you start to make a fly through, prepare all your data in the same projection. If your original data are not all in the same projection, you can use the Image Geometric Correction/Reproject in the Data Preparation Module to convert the data into the same projection. I recommend converting all raster data into Imagine image format (*.img).

1. On the command line, enter: imagine
   This opens the Imagine GUI interface.
2. Click the icon and select VirtualGIS Viewer.
   This opens a VirtualGIS Viewer window.
3. Select File/Open/DEM and choose the directory containing your DEM data. Click on the filename and click OK. You should be able to see the DEM.

• Select File/Open/Raster to drape an image on the top of the DEM.
• Select File/Open/Vector to drape a vector file in ARC/INFO format on the top of the DEM.
• You can also drape an Annotation Layer, an Intervisibility layer, or a Model layer on the DEM.
4. Select View/Level of Detail Control to adjust the level of detail. The higher the level of detail, the more detail you see, but you consume more memory and slow the display speed.
5. Select View/Scene Properties, or right click the mouse on the scene, and select Scene Properties in the popup window.

• The DEM tab allows you to change the DEM vertical Exaggeration, Terrain Color, etc.
• The Fog tab allows you to use the Fog effect on the scene.
• The Background tab allows you to use Solid Color, Fade Color, or Image as a background.
• The Motion tab allows you to change the motion (fly) speed. This is also the speed used in the flight path by default.
• The Stereo tab allows you to use stereo, and choose between Stereo-in-a-window or Full Screen. We do not use Anaglyph stereo mode on the Onyx2..
6. After you have set up all those properties, use File/Save/Project to save the project.
7. Digitize the flight path.

1. In the VirtualGIS Viewer, select the icon on the toolbar. This will generate a 2DViewer with the same layers you have in the VirtualGIS Viewer.
2. Right click the mouse and select Link/Unlink with Viewer. Click on the 2DViewer you just created. This will link your VirtualGIS Viewer with the 2DViewer.
3. Select Navigation/Flight Path Editor in the VirtualGIS Viewer to get the Flight Path Editor window.
4. Select Edit/Set Elevation and other items to set the flight height and other parameters.
5. Select Navigation/Position Editor in the VirtualGIS Viewer to define the Start position, AGL and ASL, FOV, Pitch, Azimuth, and Roll.
6. Click the icon in the Flight Path Editor window to start digitizing a flight path in the 2DViewer. You can change several parameters in the flight path table.
8. After you set the flight path, click the icon to apply changes to the flight path.
9. Click the icon to to play the fly-though.
10. Click the icon to stop the flight.
11. Save your project again.

To make an SGI movie, click on the icon in the Imagine GUI interface. Select Create Movie. You can play this movie with the movieplayer or mediaplayer command.