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Roughness Along
Roughness Around
White Hair
This parameter controls the amount of white hairs in the clump of hair.
Medulla
Synthetic Fiber
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Natural looking hair requires a slightly different variations from one hair strand to the next (having totally uniform parametrisation over the entire hair clump is generally only possible for synthetic hairs). The values in this section allow to randomly vary most parameters by a certain amount. Note that the variation is coherent from frame to frame in animation. A value of 0 indicates no variation for the parameter, a value of 1 indicates the largest possible variation and will be closer to a totally random value.
Dye Hue Variation
White Hair
This parameter controls the amount of white hairs in the clump of hair.
Technical Notes
An interesting aspect of hair rendering is that all the intricate visual details seen in hair stem from the scattering of light in a multitude of hair strands and is not due to the complexity of the BRDF on a single hair strand. This seemingly simple observation explains why so many complex shaders are not successful at conveying a realistic look for hair. This includes the widely used shaders based on the Marschner model not using volume scattering. Our shader simulates 3 scattering events from one single hair strand and then proceeds with a Monte-Carlo simulation to follow light paths inside the hair volume.
Two observations:
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Note that it offers no control over directly reflected color. Direct reflections have the same color as the incoming light. Any coloured visual features are due to light passing through a strand of hair.