This page provides information on the V-Ray Hair Next Material.
Overview
VRayHairNextMtl is specifically designed for rendering hair and fur and provides settings for a workflow based on the physiology of real hair. Instead of tweaking arbitrary colors that mix together, the new Hair Next material uses a simple melanin slider that determines the hair color just like in the real world. The material is the product of research based on the paper A Practical and Controllable Hair and Fur Model for Production Path Tracing.
Presets
Example: Presets
General Parameters
Example: Melanin
The pigmentation component that gives the hair strand its main color. The higher the value assigned, the higher the concentration of melanin, the darker the hair strands are. In the example below, pheomelanin is set to 0.
Example: Pheomelanin
The redness (pheomelanin content) of the hair strand as fraction of all melanin. 1.0 makes the hair redder. The ratio of melanin to pheomelanin determines how red your hair is. The pheomelanin amount will have no effect if melanin is set to 0. In the example below, melanin is set to 0.4.
Example: Dye color
Applies a color tint to the hair. For a dyed hair look, set the melanin to 0, otherwise the melanin will darken the dye color and pheomelanin will introduce redness to it. White means no hair dye. In the example below, the Dye color is set to pink (H=0,S=250,V=104) and the hue value is adjusted. Melanin is set to 0.4.
Example: Softness
Controls the overall softness of the hair by how much the highlights are wrapped around the individual hair strands. Higher values make the highlights wrap almost completely around the strands giving the hair a smoother look, while lower values make it look crisper. In the example below, the effect is also shown on a single hair strand. Melanin is set to 0.4.
Example: Highlight shift
Shifts the highlights along the hair strand. Positive values shift the highlight away from the root of the hair, while negative values move the highlight closer to the root. In the example below, melanin is set to 0.6.
Example: IOR
Hair index of refration. The typical value for human hair is 1.55. The higher the value, the more reflective the hair strands. In the example below, melanin is set to 0.6.
Glint
Example: Glint Strength
Controls the strength of the highlights along and across the hair strand. All other parameters are set to their default values.
Example: Glint Variation
The Glint Variation randomizes the glint effect along the strand. All other parameters are set to their default values.
Example: Glitter Size
The Glitter Size controls the size of the randomization pattern applied. The higher the value, the more variation. All other parameters are set to their default values.
Example: Glitter Strength
Controls the strength of the glitter highlights. The higher the value, the more pronounced the effect. All other parameters are set to their default values.
Example: Scale
Values below 1.0 shrink the variation pattern; values above 1.0 elongate it, so the effect is spread out.
Randomization
The Randomization parameters can be used to introduce variation of the general parameter values. When using randomization, different hair strands will receive slightly different values for the below parameters, so in fact the randomization works on a per strand basis.
Tint
Example: Primary tint
The color tint for the primary component. Corresponds to the light reflected off of the outer surface of a hair strand. In the example below the Primary tint color is set to pink (H=0,S=172,V=132) and we adjust the hue value and the melanin to 0.6.
Advanced
Example: Compensate Energy
This example shows the difference when Compensate energy option is disabled and enabled.
Notes
- Proper gamma workflow is essential for realistic rendering of hair.
References
Here is a list of references used when building the VRayHairNextMtl material.
- Chiang et al. "A Practical and Controllable Hair and Fur Model for Production Path Tracing" - 2016
(https://benedikt-bitterli.me/pchfm/) - Pharr "THE IMPLEMENTATION OF A HAIR SCATTERING MODEL" - 2016
(http://www.pbrt.org/hair.pdf) - d'Eon et al. "An Energy-Conserving Hair Reflectance Model" - 2011
(https://eugenedeon.com/pdfs/egsrhair.pdf) - d'Eon et al. "An Energy-Conserving Hair Reflectance Model" post publication review - 2011
(https://publons.com/publon/2803/) - d'Eon et al. "Importance Sampling for Physically-Based Hair Fiber Models" - 2013
(https://cg.ivd.kit.edu/publications/pubhanika/2013_hairbrief.pdf) - d'Eon et al. "A Fiber Scattering Model with Non-Separable Lobes - Supplemental Report" - 2014
(https://eugenedeon.com/pdfs/nonsephair2014.pdf) - Marschner et al. "Light Scattering from Human Hair Fibers" - 2003
(http://www.graphics.stanford.edu/papers/hair/hair-sg03final.pdf) - Zinke et al. "Light Scattering from Filaments" - 2007
(http://cg.cs.uni-bonn.de/project-pages/hairmodeling/documents/BFSDF_preprint_with_copyright_notice.pdf - no longer available) - Zinke (thesis) "Photo-Realistic Rendering of Fiber Assemblies" - 2008
(http://cg.cs.uni-bonn.de/en/publications/paper-details/Zinke2008a/ - no longer available) - Jakob (thesis) "Light Transport On Path-Space Manifolds" - 2012
(https://ecommons.cornell.edu/handle/1813/34189) - Yan et al. "Physically-Accurate Fur Reflectance: Modeling, Measurement and Rendering" - 2015
(https://cseweb.ucsd.edu/~ravir/paper_fur.pdf) - Yan et al. "An Efficient and Practical Near and Far Field Fur Reflectance Model" - 2017
(https://cseweb.ucsd.edu/~ravir/lingqi_fur2.pdf)