its mostly terragen, i use Gaea to build quickly some base structure and throw out ideas on the flow, here is a work in progress screen from gaea
i've started to use the paint brush in terragen a lot and creating some details in photoshop, then using shadermap i create depth map out of it and paint some crevices and cracks where then i apply the displacement map and the diffuse map created before, i just need to get better at masking
