I'm in the process of creating an original extrasolar earth where I'm using a layered texture to provide various different kinds of terrain (grassland, deserts, mountain ranges, etc). I'm at the point where I like the texture placements that I got, but I want to create a more 3D surface for the mountain ranges and also give the illusion of bumps and valleys in the grass areas by attaching a 2D/3D Bump Texture (not sure which one is better for this sort of thing) or by paining a bump texture onto the surface and then modifying from there. That being said, I'm not sure how to attach a bump texture without making the whole lambert bumpy whereas I just want selected areas. Any suggestions or ideas?

Thanks!

~Hunt