Visit the original blog post at http://fragileearthstudios.com/2012/09/15/generating-complex-terrains/ for additional information and sample files. Forget what you know about editing terrains. Unlike the terrain editor in Unity that functions like a paint program, World Machine (and programs like it) operate on a procedural level. A World Machine world file is not the terrain, but the steps that creates the terrain. This is the source of both its power and its complexity. This presentation covers the process on how to use World Machine in conjunction with Unity3D to generate realistic looking terrains for your scene.