Ganymede's two major terrain types are dark and light materials, each covering about 50 percent of the surface. The area between long 120 and 240 is covered by Voyager 2 images with poor resolution due to foreshortening. Part of Galileo Regio, the largest expanse of dark material on Ganymede, is in this area. The cap is visible on far-encounter images only and does not affect the contrast on the images used for geologic mapping. All attributes created during the creation process were verified by displaying the lines in both the database and the spatial coverage, but no formal tests were performed.
Line geometry is topologically clean.
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