This is just my main terrain with none of the surrounding secondary terrains.
I created my height map by saving out a terrain mesh from google sketchup 8 of an area i selected. I opened this terrain in 3d max, uv mapped the mesh in the Y, and added a gradient texture to the mesh. I then rendered out the height map in the top down view. I brought this rendered height map into photoshop and copied it onto my existing heightmapprimary.raw. I then scaled the new heightmap down to fit and deleted the old heightmapprimary layer. I saved out and over as a .raw in 1 channel.