I use either Wilbur (for planet maps) or Bryce (for regular terrain maps) to create heightmaps, and Bryce for the colormap.
I also use a custom lib to load in heightmaps as segmented meshes instead of using the default Blitz terrains, but that's largely personal preference; Blitz terrains can be sufficient depending on your needs.
I also use a custom lib to load in heightmaps as segmented meshes instead of using the default Blitz terrains, but that's largely personal preference; Blitz terrains can be sufficient depending on your needs.