Worley noise

Example picture generated with Worley noise's basic algorithm. Tweaking of seed points and colors would be necessary to make this look like stone.

Worley noise is a noise function introduced by Steven Worley in 1996. In computer graphics it is used to create procedural textures, i.e. textures that are created automatically with arbitrary precision and do not have to be drawn by hand. Worley noise comes close to simulating textures of stone, water, or biological cells.

Basic algorithm

The algorithm chooses random points in space (2- or 3-dimensional) and then for every location in space takes the distances d_n to the nth-closest point (e.g. the second-closest point) and uses combinations of those to control color information (note that d_n+1 > d_n). More precisely:

• Randomly distribute feature points in space organised as grid cells. In practice this is done on the fly without storage (as a procedural noise). The original method considered a variable number of seed points per cell so as to mimic a Poisson distribution, but many implementations just put one.
• At run time, extract the distances d_n from the given location to the nth-closest seed point. This can be done efficiently by visiting the current cell and its neighbors.
• Noise W(x) is formally the vector of distances, plus possibly the corresponding seed ids, user-combined so as to produce a color.

See also

• Fractal
• Voronoi diagram
• Perlin noise
• Simplex noise

Further reading

• Worley, Steven (1996). A cellular texture basis function (PDF). Proceedings of the 23rd annual conference on computer graphics and interactive techniques. acm.org. pp. 291–294. ISBN 0-89791-746-4.
• David S. Ebert; F. Kenton Musgrave; Darwyn Peachey; Ken Perlin; Steve Worley (2002). Texturing and Modeling: A Procedural Approach. Morgan Kaufmann. pp. 135–155. ISBN 978-1-55860-848-1.

External links

• Detailed description on how to implement cell noise
• A version with the color plates appended at the end