1. If other displays and data are already loaded, select the Edit→Remove All Displays and Data menu item or the icon in the toolbar to clear them out.
2. Load some DEM data.
   • Open the Data Choosers.
   • In the Data Chooser tree click on the Files node.
   • Go to the point data directory: /data/idv/gis/.
   • Select dem.grd
   • Under the Data Source Type pulldown menu, select "DEM Files"
   • Press Add Source
3. Create a display
   • Select Color-Shaded Plan View in the Displays section of the Field Selector and press the Create Display button.
4. Where are we?
   • To find out create a Background Image (Displays→Maps and Backgrounds→Add Background Image or with the toolbar button). Select the "Topographic Map" layer.
   • Humm, now what, we can't see the DEM image.
   • The background image is blocking the DEM display. Unfortunately we can change the Z-level of the background but it is already at the lowest level so change the vertical position of the DEM display.
5. Ok, so now we see that this DEM data set is to the west of Denver.
6. Note that the DEM display is flat, it is just a plan view. Doesn't the IDV do 3D???
   • Yes it does.
   • Remove the DEM display and select the Elevation field for the DEM data in the Field Selector.
   • Under 3D Surface in the Displays area select Topography and create the display.
   • Try changing the Display Mode to points. It looks better if you turn off the visibility of the Topographic map.
7. Now, let's try to combine the Topographic map with the DEM data. i.e., let's drape a map image over the DEM.
   • First, a tricky part: we want to somehow capture the background image over the spatial domain of the DEM data set.
     • Zoom in to the DEM image.
     • In the File→Save menu of the Background Image display control select Save Data in Cache....
     • Leave the name as is and press OK
     • Now, we have a snapshot of the Topographic map in the Field Selector
   • Remove the Topography and Background Image displays.
   • In the Field Selector select Formulas and in the Fields list, under Imagery select Image over topography.
   • In the Displays list, under Imagery select 3 Color (RGB) Image over topography and press Create Display
   • A new Field Selector will popup. Select Elevation and press OK.
   • Another Field Selector will be shown for the image field. Select Topographic map under Cached data.
   • The Topographic map should now be shown draped over the topography.
8. Try changing the vertical scale to 5000-14000 feet (View→Viewpoint→Vertical Scale menu item).
9. Let's just highlight the areas that are above 4000 meters.
   • Add a Location Indicator display with the Displays→Special→Location Indicator menu item.
   • In the Altitude field for the origin enter 4000 and hit return.
   • Under the Settings tab turn off the Visibility for the X, Y and Z axis. Turn on the Solid checkbox for X. Set the Transparency to 20%.
   • What are the names of these peaks?

Unidata IDV Workshop for version 6.1u1 > Accessing and Displaying Data > Miscellaneous Displays