I've implemented some of the suggestions that were made after the initial release. The layout is very similar to the 1st version, but the height map was recreated from scratch. Other changes include:
- more symmetrical (though not perfectly symmetrical)
- metal is more abundant and spread out more
- texture transitions are smoother in many places
I discarded my new texturing method and went back to using POV-Ray (although the various rock, grass, sand textures are the same).
Overhead view:

3D screenshot:
