We are using the procedural generation to create the undulation in the terrain or determine the distribution of trees or rocks and we are using that to fill out large areas, but the areas are specified by an artist,” says Roberts. “The way that works is that the artist can create biomes, which are templates for different areas. So you can have a template for woodland forests, or a temple for jungle, or grass land, or mountains and even within in those you can have several variations. Then you paint the big area, you basically say ‘this area is mountainous, this is woodland, and this is where the ocean is’, and then the procedural code takes that and uses that as a guide to place the biomes correctly and alter the height map. In two hours they can generate a planet and then they can spend time tweaking areas by hand.