Figure 1 Cylindrical Equidistant projection of Mars (180°W 
to 180°E, 75°N to 75°S) showing stereo coverage (height 
precision better than 1km) as black shading - based upon 
the 13472 Viking Orbiter images records contained in 
MIS. The background map is the 1^ per grid point USGS 
Flagstaff digitized airbrush map of Mars (NASA, 1992B). 
The image and stereo pair selection criteria are as speci- 
fied in section 2.2 and section 3.1. 
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