Thanks, yes it's 3 landscapes now, and my next effort is to place meshes around to give some detail (including stlagtites and stalamites, boulders and rocks, and some sort of plant cover or something over the door.
I'm also working on a cave class that will generate a cave system from a heightmap, with a couple of different cross section options and all the assocaited seaming and (if I can pull it off) GetHeight functions to help determine how to walk over or in the cave. I'm still working out that last bit though
