I generated the landscape using world machine, started with a Perlin noise based fractal, then the tool allows the user to sculpt the landscape using erosion algorithms, height modifiers, etc.

I exported a height map as a bitmap image, applied it as a displacement map in MAX, then converted to a poly shape so I could further edit the terrain to my needs.

Most of the detail there is a pocedural bump map since too many polys in the scene would be a nightmare to navigate.