Terrain
Texture and terrain can have similar procedural generation beginnings. With either, we can use a fractal or noise patterns as a basis. We can create a height map that can be wrapped around objects. An alternative for our planet in Chapter 9, Generating a 3D Planet, would have been to use a Perlin noise distortion height map.
A height map is a texture that has 3D qualities. You would then apply the height map texture to the 3D model to give the model a 3D texture. As you can see in the following figure, this is an easy way to create a terrain.
Besides the actual texture of the ground, tons of work has gone into making tree and foliage generators. Terrain is one of the better defined constructs in PCG. This is a good starting point for anyone learning 3D PCG.