Digital Elevation Model (DEM)
This service uses Shuttle Radar Topography Mission, version 2, data from NASA. It was created in 2000 and has a resolution of either 30m or 90m. Most of the world's landmass (99%) is covered between -60 and +60 degrees as standard. For high latitude regions such as Scandanavia, Northern Canada, Greenland and Iceland, extra tiles have been added courtesy of Jonathan de Ferranti at viewfinderpanoramas.org.
Global 90m/240ft coverage
You can view our data in Google earth/maps with these links:
30m/90ft coverage (USA)
To enhance the terrain data with man made obstacles such as buildings and pesky wind turbines there are two clutter layer options available. You can either choose to simulate random clutter at a set height eg. 8m for houses in a suburban area, or upload your own defined 'precision' clutter as a KML layer (Polygon,Polyline,Points all ok). Once loaded you can use the precise clutter by selecting 'Own clutter' in the interface or go wild and select 'all clutter' to benefit (or not) from other users contributions.