3 - Practical Methods for Texture Design

Abstract

This chapter discusses the practical methods for texture design. Many new textures are just variants of each other—new ways to organize a set of stock routines together. Building blocks such as fractal noise functions, color mapping methods, and bump mapping definitions occur in nearly every texture. The chapter discusses these common elements as their ubiquitous use immediately makes them important. Fractal noise is the most important element used in procedural texturing. The biggest problem with the “plain” fractal noise algorithm is artifacts. The basic routine interpolates over a cubic lattice, and one will be able to see that lattice on one's surface especially if one is using a small number of summed scales. Purists will also note that the basic Perlin noise is not very isotropic as diagonal directions have a longer distance gap between sample points than the points along the coordinate directions. A good way to hide this artifacting is to rotate each summed scale to a random orientation.