'Procedural Landscapes with Overhangs' by Gamito and Musgrave covers exactly this! http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.2.1625&rep=rep1&typ

'Procedural Landscapes with Overhangs' by Gamito and Musgrave covers exactly this! http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.2.1625&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.2.1...