These images display the meter-scale roughness of the Venus surface
(characterized by its root-mean-square average slope), as observed by
the Magellan radar altimeter during its 24 months of systematic
mapping.  The lightest shades locate areas having the highest values of
roughness, while darker shades indicate areas that are smoother.  The
upper image shows that part of the planet between 69 degrees north and
69 degrees south latitude in Mercator projection; beneath it are the
two polar regions covering latitudes above 44 degrees in stereographic
projection.  Easterly longitudes run across the Mercator map from left
to right, and around the periphery of the polar stereographic
projections.  Resolution of the surface varies with spacecraft
altitude, being about 10 kilometers near the equator and degrading to
as much as 25 kilometers at high latitudes.  Black areas indicate where
data were not obtained by Magellan.

There is a tendency for elevated regions, e.g. the Maxwell Montes (at
top center) and Aphrodite Terra (along the equator at right), to show
steeper meter-scale slopes than are typical of lower-lying areas.  The
steeper slopes probably result from disruption of the surface
associated with tectonic activity in these regions.  Note the large
2300-kilometer (1400-mile) diameter circular feature (Artemis Chasma)
in the lower right of the Mercator image. This feature is thought to
have been caused by a gigantic plume of heated rock rising from the
planet's interior.  The data shown here were compiled and analyzed at
the Center for Space Research, Massachusetts Institute of Technology.