DEM

http://en.wikipedia.org/wiki/Digital_elevation_model

Digital elevation model is a high-tech way of showing elevated or three dimensional maps. DEM maps can show you the physical features of an area without being there, showing depressions in the land, or rises of mountains. The picture above is of the Tithonium Chasma on Mars, as you can see the different depressions and rises in the land of a place far away.