Ken Musgrave's work on Terrain rendering is worth a look. He did similar things. The book 'Texturing and Modeling: A Procedural Approach' gives a nice explanati

Ken Musgrave's work on Terrain rendering is worth a look. He did similar things. The book 'Texturing and Modeling: A Procedural Approach' gives a nice explanation of a lot of the techniques and they used to give a course at SIGGRAPH on which the book was based but I can't find a link right now