• Source: Wavelet noise

Wavelet noise is an alternative to Perlin noise which reduces the problems of aliasing and detail loss that are encountered when Perlin noise is summed into a fractal.




Algorithm detail


The basic algorithm for 2-dimensional wavelet noise is as follows:

Create an image,



R


{\displaystyle R}

, filled with uniform white noise.
Downsample



R


{\displaystyle R}

to half-size to create




R

↓




{\displaystyle R^{\downarrow }}

, then upsample it back up to full size to create




R

↓↑




{\displaystyle R^{\downarrow \uparrow }}

.
Subtract




R

↓↑




{\displaystyle R^{\downarrow \uparrow }}

from



R


{\displaystyle R}

to create the end result,



N


{\displaystyle N}

.
This results in an image that contains all the information that cannot be represented at half-scale. From here,



N


{\displaystyle N}

can be used similarly to Perlin noise to create fractal patterns.




External links


Wavelet Noise Paper at pixar.com.

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