I want to generate a terrain that has a few overhangs, and some caves. So a simple height field from a 2D noise is out, as there would be no overhangs.
The other extreme, to define a world from a 3D noise field (I typically use marching cubes over a noise field) results in a wildly chaotic terrain.
What would be a good compromise between these two?
Something that produces mostly hills (like a height field), yet exhibits the occasional overhang/cave?
I've added a bias towards 'air' at high altitude, and a bias towards 'dirt' at low altitude, but that only helps me so far. It looks a bit better, but still too alien to be a real terrain.
Any quick hacks I can try, without actually having to simulate gravity, geology, and weather systems?