# Phong roughness¶

Carbon reflective material associated with phong roughness

The Phong roughness model is based on the specular part of the classical Phong BRDF. The slope distribution is isotropic, and controlled by an exponent parameter. An exponent =0 corresponds to the maximum roughness, while infinity corresponds to no roughness (perfectly flat surface). For high values, exponent is equivalent to 2/α², where α is the standard deviation (RMS) of the surface slope.

## Children nodes¶

<roughness name="roughness" type="phong">