Hi John, I use mostly 1 Degree DEM's and they work fine in Vue 4. What I do is first decompress the DEM's in 3DEM, then merge them as a giant DEM and then import them in Vue. I am working on a Grand Canyon scenery out of 25 DEM's and it works fine. Check out this listing of 7.5 Minute DEM's here: http://www.timster.net/maps/states.htm Cheers!