Creating a 3D Terrain Model and Flyover

Bonnie J. Brown

CAST – University of Arkansas, Fayetteville

First you need to figure out what data you need. This is sort of like getting the ingredients together for a recipe. The basic data you are going to need for this is elevation data, which is in raster format. You may wish to add vector data or a DOQ into it.

The instructions here will take you through using digital elevation model (DEM) data from the National Elevation Dataset.

If you are from Arkansas, follow the instructions for data download and preparation here:

http://www.cast.uark.edu/east/support_info/Arkansas_elev_data.htm

If you are from any state follow the instructions for data download and preparation here:

http://www.cast.uark.edu/east/support_info/elevation_data_anystate.htm

3. Once you have downloaded and prepared your data, go to the Add Theme button. It looks like a plus-sign sitting on a diamond. You can also go to the View menu and click, “Add Theme.”

4. Change the data source type to Grid. Browse for the data you just prepared and select that as the theme you want to add. Your view will look similar to the one below.

5. The numbers to the side of the different shades, are the values for the elevations. Elevation is measured in number of meters above sea level. In the example above, the darker reds represent higher elevations.

6. Double click on the legend and change the color ramp (located at the bottom of the Legend Editor) to Terrain Elevation #3. (This step is optional, you can make it any color scheme you wish. The terrain elevation schemes however, generally allow for a nice visualization) Close the Legend editor.

Now go to the View menu and select 3D Scene. You have a choice to add it as a theme or an image. Choose Image and click OK. Your 3D scene will be similar to the image below. Don’t worry about the white around the DEM.

Navigating around the 3D scene is a bit different than the 2D. Use the icon that looks like a ship to move and rotate the scene.

NOTE: There is a button that will make your 3D scene spin around.

Do NOT click that button until you have your main ArcView window maximized. You will not be able to stop it from spinning if you can’t get to the Stop button in the lower right corner of the screen. You won’t be able to see that Stop button unless the main ArcView window is maximized.

You may have noticed that your 3D scene looks pretty much 2D. That’s because we haven’t added the third dimension yet. Go to the theme menu and select 3D properties. In the “Assign base heights by:” section select surface and then click the browse button next to the white box.

When the Get Source window pops up. Select your elevation data. It should be a Grid source type

The Z factor determines the amount of exaggeration to your elevation. Its something you will need to adjust to get the visualization you are looking for. Start out by changing your Z Factor to a number between 1 and 10. Then make your adjustments according to the look you want. Click OK.

Now you have a basic 3D terrain model. The next section will show you how to create a “flyover,” of your terrain model.

The “Flyover.”

To create a flyover you will need to download a special extension for ArcView 3D Analyst. The next few slides will cover the download and installation process for an extension called 3D InControl. It is freeware so you don’t need to worry about licensing.

First go to the following web page. http://arcscripts.esri.com/ Change the search parameters from “All ESRI Software” to “ArcView GIS. In the “Search For” box, type “3d AND fly.” When the search is complete, Click on 3DInControl.

Click the download button. The next page has information regarding public domain, copyright, etc. Scroll down and accept the agreement

When you get the file download window. Click save. The file will come to you zipped. You will need to use an application such as ultimate zip, winzip or the like to unzip or extract the file

Unzip the file to the path specified

C:\ESRI\AV_GIS30\ARCVIEW\EXT32

IMPORTANT: 3DInControl comes with a Read Me file that has some specific information on how to use the extention. You will need to get it out of the EXT32 folder once you have extracted the file.

Go back to ArcView. If you still have your 3D scene up close it. Go to the File menu and select Extensions. Check 3DInControl. Go back and open up your 3D scene again.

Click the Add Theme button.

Add the grid file for your elevation data but do not click the check box next to it.

Click once on the grid them you just added so as to make it the active theme. Go to the Theme menu and select 3D Properties.

Assign base heights by Surface. Then browse for your grid theme as you did with your image theme.

Set your Z factor to the same value as your image theme.

Click OK

Click the blue button to the far right. After you click it you should see a little control panel pop up.

Click the button that looks like a little globe.

Arrange the windows so that you can see the 3D scene, the 3D Scene PlanView, and the Control panel.

Target

Observer

The PlanView is the window where you will draw your flight plan. The target (in red) is the location where you, the observer (in black) will be looking.

To change the observer location, click the blue and black button. Then click the location in the PlanView.

To change the target location, use the button with the circle and crosshairs.Observer

Target

Click the button with the squiggly to draw your flight path in the PlanView.

Once you have your flight plan drawn, you will need to check other settings in the control panel. You can change any of the numeric values by clicking the up or down arrows.

Step: Controls your speed of flight.

Observer: The altitude must be set higher than the highest elevation in your DEM.

Target: Should be equal to or lower than your observer. You may find that every time you change your flight path, you must reset your target and observer values.

Angle, Roll and Rotate. These should be set to your personal preferences

Try first looking at the Target at a Constant altitude. (If you look In Front and have your altitude Above Terrain, you will find it a bit jerky.)When you are ready to fly, click the little running man.