Whilst accepting Gebe's remarks about the range of tools available in the terrain editor, I have to agree with ShadowWind that it can be a rather blunt instrument, particularly if you are trying to recreate an actual real-world terrain. I know Mikeangelo also had to work very hard at this in his images of real scenes. If I were to tackle this sort of project, I would be inclined to pursue the external modeller route. Some of my own terrains have been created with nothing more complex than painting the grayscale heightfield map using PSP7.