DEM Difference Maps
Select from the Raster GIS menu, Multiple grid arithmetic.
DEM difference maps will be drawn in one of two ways:
 If the DEMs/grid are compatible the difference will be computed for each grid
location.
 If the DEMs vary and are not compatible, the new grid will match the first
of the two DEMs in extent and point spacing. At each location in that
grid, the elevation in the other grid will be
interpolated. Reasons for the grids varying could be
different extents, or one DEM being UTM and the other Lat/Long.
The order of selecting the two DEM will determine the sign of the result.
The second DEM will be subtracted from the first. The title of the map
will show the order of the subtraction. If you want, you can change the
sign of the results using Single grid arithmetic
on the Edit menu.

You can get:
 XY scatter plot for the two grids.
 Histograms for the two grids and the difference.
 A difference map.

Last revision 12/20/2011