DEM

http://igs.indiana.edu/allenCounty/dem.cfm

A dem is a digital elevation model, and is a digital representation of ground surface topography or terrain using raster grid or triangle irregular network.Various color ramps may be applied indicating the different elevations. The hillshade may be viewed in shades of gray as seen in the above elevation, or it can be enhanced with a colored version of a DEM in a map view.