Mountains, Cliffs, and Caves: A Guide to Using Perlin Noise for Procedural Gen

Self-similarity is a really nice property for lots of sound synthesis too, so textures like water, fire and wind can make use of Perlin control and basis signals.

I managed to write a glsl shader that generates perlin noise with octaves, and pull that data as 32bit float.

Much simpler than using opencl or cuda.

As someone who has simply studied a bit of geology I agree with you--noise-generated mountains look wrong. Long ago I played around with attempting to generate terrain with faults (take a line across the world, raise everything on one side, lower everything on the other. Start with some big ones, then add more making the step size smaller as you go) followed by erosion (pick a pixel that's a local maximum, move a portion of the difference between it and the lowest neighbor to that lowest neighbor, that's the new cursor, repeat until everything around is equal or higher.) Very compute-intensive, though, and not suitable for on-the-fly generation (the faulting step might be possible with a noise generator, I see no way to do the erosion and without it everything's too harsh.) At the macroscopic level it looked a lot more realistic, I had neither the memory nor the CPU power to do too fine a model. I simply couldn't hold a large map, nor were 16-bit integers granular enough to make good slopes.

I can look at real terrain and do a pretty good job of judging whether it will be easy/hard/impossible, I've never seen a game map where that was true.