Roughness

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roughness-2014.png

A roughness node describes a 2D surface slope distribution. It may model a broad range of surface finishes, including anisotropic and measure-based ones.



Zero

Carbon reflective material associated with zero roughness

Summary

The Zero roughness model corresponds to an ideal, perfectly smooth, specular surface.

Link

Zero roughness reference


Cosine

Carbon reflective material associated with cosine roughness

Summary

The Cosine roughness model is a very simple one : the probability of a given slope is proportional to its cosine. It corresponds to a very rough surface. It is strictly equivalent to phong with the exponent parameter set to 1.

Link

Cosine roughness reference


Phong

Carbon reflective material associated with phong roughness

Summary

The Phong roughness model is based on the specular part of the classical Phong BRDF, controlled by an exponent parameter.

Link

Phong roughness reference


Beckmann

Carbon reflective material associated with beckmann roughness

Summary

The Beckmann roughness model is based on an isotropic gaussian distribution of slopes. Its roughness parameter corresponds to the standard deviation (RMS) of the slope. A value of zero corresponds to a perfectly smooth specular surface.

Link

Beckmann roughness reference


Ashikhmin-Shirley

Carbon reflective material associated with Ashikmin-Shirley roughness. The nu and nv parameters are spatially varying using a directionnal noise pattern, orthogonal to the main scattering direction V

Summary

The Ashikmin-Shirley roughness model is an anisotropic generalization of the phong model, based on the paper "An Anisotropic Phong BRDF Model".

Link

Ashikhmin-Shirley roughness reference


Map

Carbon reflective material associated with a map roughness. The isotropic distribution image is shown at the right, it combines a classical gaussian roughness with cone-like structures having slopes around 20°

Summary

The map roughness allows giving a custom roughness distribution as an image, representing the normal distribution as a function of theta (vertically) and phi(horizontally).

Link

Map roughness reference


See also

Node types