Ok, I'm here again with a realistic high-resolution Ganymede texture
The NASA map was used as the main source, and the polar + some other areas were filled by Björn's texture. All connection lines of different colors and resolutions were smoothed out with a minimal loss of information. As always, I strove for the most realistic color, but I can't ensure high accuracy. The color was selected by mixing channels, the texture is gamma-corrected.
It's ready for use in Celestia. Celestia Origin uses a Virtual Texture version of this map.Sources:
Ganymede color map by USGSBjörn Jónsson's map of Ganymede