[VRayFastSSS example]

 

General

Parameters

General parameters

Diffuse parameters

Primary specular parameters

Secondary specular parameters

Transmission parameters

Options

Maps

Notes

References and links

 

Search keywords: hair, fur

General

VRayHairMtl is a material that is primarily designed for rendering of hair and fur. It can be used to render geometry generated through the VRayOrnatrixMod modifier, the VRayFur primitive, or the 3ds Max Hair&Fur modifier (when in "mr prim" mode).

 

The material is based around three components - primary specular component, secondary specular component, and a transmission component. A diffuse component is also provided for rendering of materials made up of cloth threads or other non-translucent fibers.

 

The following image illustrates the meaning of the three components:

The primary specular component represents light that is reflected off the outer surface of a hair strand. The secondary specular component represents light that goes through the hair strand and is reflected off the back surface. The transmission component represents light that goes through the hair strand.

Parameters

General parameters

[General parameters]Preset - allows you to choose one of several available preset materials.

 

Overall multiplier - a common color multiplier for all color components in the material (except for opacity). Used to easily change the look of the entire hair material.

 

Opacity - controls the transparency of the material where white is opaque, and black is fully transparent. The opacity can be mapped along the hair strands using the VRayHairInfoTex texture. Making the hair more transparent towards the tip may produce more smooth and realistic anitaliasing at the expense of increased render times. If you map the tip opacity, make sure you don't make the strands thinner at the tip as well - transparency already creates the effect of thinning strands. You can enable the Opaque for shadows and Opaque for GI options to reduce render times for transparent hair. Note that with transparent strands, it may be necessary to increase the Max. transp. levels option in the global V-Ray settings too.

Diffuse parameters

[Diffuse parameters]Diffuse - controls the diffuse component of the shader. Use this for materials made out of cloth threads or other non-translucent fibers, as well as for dirty hair. Note that clean hair or fur does not normally have a diffuse component, so in that case leave the parameter black.

 

Diffuse amount - the amount for the diffuse component of the material.

Primary specular parameters

[Primary specular]The primary specular component corresponds to light that is reflected off the outer surface of hair strands (see the figure above).

 

Primary specular - the primary specular color component. Normally this is dark gray.

 

Primary specular amount - a multiplier for the primary specular color.

 

Primary glossiness - the glossiness for the primary specular component. Values closer to 1.0 make the hair more shiny and sleek. Lower values give it a matted look.

Secondary specular parameters

[Secondary specular]The secondary specular component corresponds to light that is reflected off the back surface of the hair strands.

 

Lock to transmission - if this is enabled (the default), the color for the secondary specular component is derived from the color of the transmission component. Since a ray of light goes twice through the hair width, the color of the secondary specular component can be computed by multiplying the transmission color with itself. When this option is enabled, the hair color is mostly determined by the transmission color component.

 

Secondary specular - the color of the secondary specular component. If Lock to transmission is enabled, this value is ignored and the secondary specular color is derived from the transmission color.

 

Secondary specular amount - a multiplier for the secondary specular component. If Lock to transmission is enabled, this value is ignored and the secondary specular amount is derived from the transmission amount.

 

Secondary glossiness - the glossiness for the secondary specular component. Values closer to 1.0 correspond to shiny and sleek hair. Lower values correspond to matted hair.

Transmisson parameters

[Transmission parameters]The transmission component corresponds to light that goes through the hair strands.

 

Transmission - the color for the transmission component. When Lock to transmission is enabled, this color determines the overall hair color.

 

Transmission amount - the amount of the transmission component.

 

Transmission glossiness length - the glossiness of the transmission along the hair strand length. See the Examples for a demonstration of the effect of this parameter.

 

Transmission glossiness width - the glossiness for the transmission component across the hair strand width. See the Examples for a demonstration of the effect of this parameter.

Options

[Options]Opaque for shadows - when this is enabled, the hair material is always opaque for shadow calculations. This speeds up the rendering of transparent hair.

 

Opaque for GI - when this is enabled, the hair material is always opaque for GI calculations. This speeds up the rendering of transparent hair.

 

Simplify for GI - when enabled, a simplified diffuse version of the BRDF is used for GI calculations. This may speed up the rendering of hair but may significantly change the final look.

 

Use cached GI - this option is similar to the Use irradiance map option for the VRayMtl material; if it is enabled, the hair material will always be calculated with brute force GI.

Maps

The parameters in this section allow the various components to be mapped with textures. The VRayHairInfoTex texture can be used for mapping a parameter along the strand length or to get the color from the 3ds Max Hair&Fur modifier.

Notes

References and links

Here is a list of links and references used when building the VRayHairMtl material.