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Spectral Synthesis & Procedural Functions

The spectral synthesis algorithm is taken directly out of Darwyn Peachey's chapter in Texturing & Modeling: A Procedural Approach by Ebert, Musgrave, Peachey, Perlin, and Worley. It's an exceptionally good book, I highly recommend it to anyone interested in learning about procedural techniques. The detailed description begins on p82 and I also use the spline interpolation function on p31. If you can, read that chapter over as they probably explain it better than I do as I'm trying not to plagerise too much.

Spectral Synthesis is a noise function - which means it doesn't fit any easily noticable pattern. Noise functions are extremely useful, almost anything in nature can be approximated by some combination of pattern and noise. The trick is knowing how to combine them. Consider how powerful a relatively simple function like is outlined here can be. High end & photorealistic renderers use many procedural functions for generating realistic textures and models. Pixar's Renderman rendering system is designed around taking advantage of the power of procedural functions. Besides being able to generate lots of varying patterns, procedural textures hardly require any storage space because they can be generated at run time (or on the fly) instead of being stored as a 24-bit texture on disk. Procedural textures have not been taken advantage of much in the game industry - except probably in generating textures in Adobe Photoshop, or another paint program. Now that video cards are more powerful, games can produce incredibly detailed scenes, and procedural textures and models are going to be a requirement to generate the massive amounts of data necessary for a highly detailed world.

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