Unidata IDV Workshop for version 6.3 > Accessing and Displaying Data > Miscellaneous Displays
3.11.7 DEM Displays
The IDV supports elevation data from models, USGS DEM format
and ESRI's ArcInfo ASCII grid format.
- If other displays and data are already loaded, select the
menu item
or the
icon in the toolbar to clear them out.
- 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
- Create a display
- Select
Color-Shaded Plan View
in the Displays
section
of the Field Selector
and press the Create Display
button.
- Where are we?
- To find out create a 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.
- Ok, so now we see that this DEM data set is to the west of Denver.
- 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.
- 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 menu of the
Background Image
display control select
.
- 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.
- Try changing the vertical scale to 5000-14000 feet ( menu item).
- Let's just highlight the areas that are above 4000 meters.
- Add a
Location Indicator
display with the
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 6.3 > Accessing and Displaying Data > Miscellaneous Displays