Page Contents

 

Overview


The Hair material is primarily designed for rendering hair and fur. The material is based around three components: a primary specular component, a 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 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.

The image below illustrates the meaning of the three components:

 

 

Parameters


 

 

 

Overall Color – 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.

Transparency – Controls the transparency of the material. Making the hair more transparent towards the tip may produce more smooth and realistic anti-aliasing at the expense of increased render times. If you map the tip opacity, make sure you do not make the strands thinner at the tip as well - transparency already creates the effect of thinning strands. You can enable the Opaque Shadows and Opaque 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 Switches rollout of the V-Ray settings too.

 

Diffuse


 

 

 

Color – 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 such a case, leave the parameter black.

Amount – The amount of the diffuse component of the material.

 

Primary Specular


 

 

 

Color – The primary specular color component, which corresponds to light that is reflected off the outer surface of hair strands (see the figure above). Normally this is dark gray.

Amount – A multiplier for the primary specular color.

Glossiness – The glossiness for the primary specular component. Values closer to 1.0 make the hair shinier and sleeker. Lower values give it a matted look.

 

Secondary Specular


 

 

 

Lock to Transmission – When 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.

Color  – The color of the secondary specular component, which corresponds to light that is reflected off the back surface of the hair strands. If Lock to Transmission is enabled, this value is ignored and the secondary specular color is derived from the Transmission color.

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.

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.

 

Transmission


 

 

 

Color – The color for the transmission component, which corresponds to light that goes through the hair strands. When Lock to Transmission is enabled, this color determines the overall hair color.

Amount – The amount of the transmission component.

Glossiness L/W – The glossiness of the transmission along and across the hair strand length. For more information, see the Transmission Glossiness Length and Width Parameters example below. 

 

 


 

Example: Transmission Glossiness Length and Width Parameters


This example shows the effect of the Transmission Glossiness Length and the Transmission Glossiness Width parameters. It shows a number of vertical strands (in this case, produced by VRayFur) lit from behind by a spherical light.

Note how each parameter changes the way light scatters along the length and the width of the strands. Higher values for the length glossiness compress the transmission highlight along the strand length, while lower values expand it.

 


Transmission Glossiness Length: 0.87
Transmission Glossiness Width: 0.98

 


Transmission Glossiness Length: 0.85
Transmission Glossiness Width: 0.95

 


Transmission Glossiness Length: 0.95
Transmission Glossiness Width: 0.85

 


Transmission Glossiness Length: 0.98
Transmission Glossiness Width: 0.87

 

 

 

Options


 

 

 

Opaque Shadows – When enabled, the hair material is always opaque for shadow calculations. This speeds up the rendering of transparent hair.

Opaque for GI – When 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 – Similar to the Use Irradiance Map option for the VRayMtl material; if it is disabled, the hair material will always be calculated with brute force GI. 

Light Multiplier – In the absence of GI, the hair may look very dark. GI is the proper way to correct this, but if GI must be really avoided, this multiplier can be used to brighten the hair.

 

Multipliers


 

 

Mode – Specifies how textures and colors are blended by the multipliers. 

Multiply – When set to Multiply, the texture is blended with black color. 
Blend Amount – When Blend Amount is selected, the user-specified color is used for blending. 

Overall Color – Blends between the assigned texture and the mode specific color. 

Transparency – Blends between the assigned texture and the mode specific color. 

Diffuse Color – Blends between the assigned texture and the mode specific color. 

Primary Spec. Color – Blends between the assigned texture and the mode specific color. 

Secondary Spec. Color – Blends between the assigned texture and the mode specific color. 

Transmission Color – Blends between the assigned texture and the mode specific color. 

 

Material Options


 

 

 

Can be Overridden – When disabled, the material will not be overridden by the Material Override option in the Render Settings.

 

 

Maps


These determine the various texture maps used by the material.

Bump/Normal Mapping

 

 

 

Bump/ Normal Mapping – Enables or disables the bump or normal effect.

Mode/Map – Specifies the map type. 

Bump Map
Local Space Bump 
Normal map 


Advanced Options

 

Normal Map Type – Specifies the normal map type. 

Tangent space
Object space
Screen space
World space 

Delta Scale – Decrease the value of the parameter to sharpen the bump, increase it for more blurry effect of the bump. 

 

Displacement




Displacement – Enables or disables the displacement effect.

Mode/ Map – Specifies the mode in which the displacement will be rendered. 

2D Displacement – Bases the displacement on a texture map that is known in advanced. The displaced surface is rendered as a warped height-field based on that texture map. The actual raytracing of the displaced surface is done in texture space and the result is mapped back into 3D space. The advantage of this method is that it preserves all details in the displacement map. However, it requires the object to have valid texture coordinates. You cannot use this method for 3d procedural textures or other textures that use object or world coordinates. The parameter can take any values. 
Normal Displacement – Takes the original surface geometry and subdivides its triangles into smaller sub-triangles, which then are displaced. 

Amount – The amount of displacement. A value of 0.0 means the object appears unchanged. Higher values produce a greater displacement effect. This parameter can also take a negative value, in which case the displacement will push geometry inside the object. 

Shift – Specifies a constant, which will be added to the displacement map values, effectively shifting the displaced surface up and down along the normals. This can be either positive or negative.

Keep continuity – When enabled, tries to produce a connected surface, without splits, when there are faces from different smoothing groups and/or material IDs. Note that using material IDs is not a very good way to combine displacement maps since V-Ray cannot always guarantee the surface continuity. Use other methods (vertex colors, masks etc) to blend different displacement maps.

View dependent – When enabled, Edge length determines the maximum length of a subtriangle edge in pixels. A value of 1.0 means that the longest edge of each subtriangle will be about one pixel long when projected on the screen. When disabled, Edge length is the maximum sub-triangle edge length in world units.

Edge length – Determines the quality of the displacement. Each triangle of the original mesh is subdivided into a number of subtriangles. More subtriangles mean more detail in the displacement, slower rendering times and more RAM usage. Less subtriangles mean less detail, faster rendering and less RAM. The meaning of Edge length depends on the View dependent parameter. 

Max subdivs – Controls the maximum sub-triangles generated from any triangle of the original mesh when the displacement type is Subdivision. The value is in fact the square root of the maximum number of subtriangles. For example, a value of 256 means that at most 256 x 256 = 65536 subtriangles will be generated for any given original triangle. It is not a good idea to keep this value very high. If you need to use higher values, it will be better to tessellate the original mesh itself into smaller triangles instead. The actual subdivisions for a triangle are rounded up to the nearest power of two (this makes it easier to avoid gaps because of different tessellation on neighboring triangles). 

Water Level – Clips the surface geometry in places where the displacement map value is below the specified threshold. This can be used for clip mapping a displacement map value below which geometry will be clipped. 

Level Height – Value below which the geometry is clipped. 

 

 

Environment Overrides


Allows Background, Reflection, and Refraction maps from Environment Settings to be overridden for the current material.

 

 

 

Background Environment

Texture – Specifies a texture to be used as the overriding map.

Multiplier – Specifies a multiplier for the overriding map.

Reflection Environment

Texture – Specifies a texture to be used as the overriding map.

Multiplier – Specifies a multiplier for the overriding map.

Refraction Environment

Texture – Specifies a texture to be used as the overriding map.

Multiplier – Specifies a multiplier for the overriding map.