The textures that we have discussed to this point are two-dimensional functions mapped onto two-dimensional surfaces. Another approach is to consider a texture as a function defined over a three-dimensional surface. Textures of this type are called solid textures.

Solid textures are very effective at representing some types of materials such as marble and wood. Generally, solid textures are defined procedural functions rather than tabularized or sampled functions as used in 2-D (Any guesses why?)

The approach that we will explore is based on
An Image Synthesizer, by Ken Perlin,
SIGGRAPH '85. The vase to the right is from this paper.