> For each map resolution, the
data set contains images of planetary radius, topography, and the
number of MOLA shots within a grid cell (referred to as counts).
Topography is computed as the planetary radius minus the areiod
raduis. Images of the Mars areoid are provided at resolutions of 4,
16, and 32 pixels per degree. See the DS.CAT file in the CATALOG
directory for details about the areoid model used for this data set.