DEM

Digital Elevation Module (DEM) format is a USGS raster data format originally developed in 1992 and retired in 2006, typically used for terrain elevation.   Despite the age of the format, much data is still available in DEM.    DEM files normally provide projection information, so when an image is imported by Manifold from DEM format it will be correctly georegistered.

 

dlg_import_dem.png

 

To import from DEM format:

 

  1. Choose File-Import from the main menu.

  2. In the Import dialog browse to the folder containing data of interest.

  3. Double-click the file ending in .dem for the data of interest.

  4. A table and image will be created and possibly a comments component as well.

 

 

eg_import_dem01_01.png

 

The comment component above provides metadata text extracted from the DEM.  The image shows the terrain elevation data.  We can double-click on the image to view it.  

 

eg_import_dem01_02.png

 

For a more interesting display, we first create a new data source using a Bing street maps imageserver as shown in the Example: An Imageserver Tutorial topic.   We then create a map and drag and drop the Bing layer into the map, and then we drag and drop the grand_canyon_e image into the map.

 

eg_import_dem01_03.pngeg_import_dem01_04.png

 

We use the Style panel in the Contents pane to color the image and to apply hill shading, as seen above.

 

eg_import_dem01_05.png

 

The result is a much more interesting and understandable display.

 

eg_import_dem01_06.png

 

Zooming in we see the DEM has provided reasonably detailed data for a basic overview of the region.

Notes

Use Merge Images - DEM files tend to be very small files by modern standards.  We may find ourselves downloading very many to get reasonable coverage of an area of interest.   To merge many terrain elevation images into a single image, which is much easier to work with, we can use the Edit - Merge - Merge Images command.

 

See Also

Style

 

Maps

 

Images

 

DEM, GTOPO30

 

Example: Spectacular Images and Data from Web Servers