Why does Terrain Navigator Pro export 2 .DEM files when exporting Elevation data.
Terrain Navigator Pro, in a typical area, has two sources of elevation data available for constructing 3-D images, profiles, and other elevation features. These consist of two files, a .EVH file that covers the same area as a 1:100,000 topographic map (3 arc seconds) and a .MTH file that covers the same area as a 1:24,000 topographic map (with 30-meter accuracy.)
When the "Save DEM" option is checked when exporting a map from Terrain Navigator Pro, the .EVH and .MTH files (assuming both are available) will be converted into the .DEM or .BIL format for processing by other GIS applications. The 1:100,000 data will have an extra "e" in the file name.