The Sheen layer can simulate the grazing coloration or rim lighting in fabrics like velvet. It can also simulate layers of dust. 


Sheen Layer

Figure 1: Sheen layer parameters

 

Sheen Layer Parameters

Enabled - Determines whether the material layer contributes to the overall layered material system.

Sheen - The Sheen layer's color.

BRDF Model - The BRDF (Bidirectional Reflectance Distribution Function) is a function that determines the amount of light reflected from a material when light falls on it. For Sheen materials, the Sheen option creates an overall sheen across the surface and the Fuzz option create a more subtle micro-fiber effect (like peach fuzz or fine hair).

Roughness

Roughness - The Sheen layer's roughness. Higher values spread the sheen color to larger parts of the surface.

Affect Roughness - The percentage of roughness affecting subsequent layers' roughness.

Geometry Properties

Bump - Simulates a relief by using a Greyscale texture interpreted as a Height map for the layer.

Bump Height - Determines the height represented by a normalized value of 1.0 in the bump texture. A vaule of 0 disables the bump map and a negative value will invert the bump map.

Normal - Distorts Layer normals by using an RGB image.

Layer Properties

Layer Opacity - Controls the material layer opacity. A value of 0 will make the layer completely invisible revealing the layer below. 

Layer Weight - Defines the brightness/intensity of the layer's effect. Values less than 1 and closer to 0 make the layer appear darker and less intense, acting as an energy-scaling multiplier for the diffuse channel of the layer.