An overview of Gabor noise parameters

In this post we tabulate some of the parameters of Gabor noise as provided in Cycles'Open Shading Language.

In a previous post I presented a small OSL node that gives access to the fairly new Gabor noise that is available in OSL. I already showed some examples of how to use it and made an attempt to implement a fabric shader based on this noise. To help visualize the parameters of this noise I made the overview shown below (click to enlarge):

Gabor noise has tree modes:

  • Isotropic
  • Anisotropic
  • Mixed
These modes are triggered by the values 0, 1 and 2 of the anisotropic parameter. In isotropic mode the direction parameter is ignored but in the other modes the length and direction of this vector determine the frequency and the direction of the anistropy.

The impulses parameter determines the number of features (bumps) present per unit area, whereas the bandwidth parameter determines how much detail of these bumps is visible.

In the image above the colored squares show a systematic variation of these parameters. Gabor noise has a value between [-1, 1] centered around zero (the green in the colored examples). The black and white examples show some specific patterning that is possible if you choose suitable cutoffs for the noise values. They we created using the following node setup:

Note that the add/divide nodes on the left to nothing more than map the [-1, 1] range to [0, 1]. The less than/ more than nodes in combination with the multiply node pass on a value if its between the two limits or zero otherwise.

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