Things like this can be Modeled in Bryce by useing Primitives or by using Lattices...Do your Greyscale texture in PS or PSP and then bring into the Terrain Editor and then bring in as a photo,Apply then smooth if you need to,Wappen(Online name)is Famous for doing Models in the terrain editor...But I hear Sketchup is one heck of a program adn DerJimi just makes that proggy Rok and Roll...