Here is a Canyon terrain tile i created using a USGS geo tiff that i recombined with a heightfield map generated in Geo Control 2. I then imported the mesh into Maya and reduced it from 2.3 million polygons to 12000 (and cleaned the mesh). Then imported the 12k mesh into Mudbox and regenerated all of the subdivisions levels. Geo Control allowed me to create a base diffuse map which i then combined with an ambient occlusion map from Mudbox and a Cavity map from xNormal. The tangant space normal map was generated in Mudbox. This tile only uses a 1024 diffuse and normal map. The screenshot is from Mudbox.