Al Surface Material

The V-Ray AL Surface shader is V-Ray's implementation of Anders Langland's alShader, which is designed to reproduce the appearance of skin. The current version takes into account diffuse reflection, two levels of reflection, and subsurface scattering.

||V-Ray|| > Al Surface Material

||Create|| > V-Ray > Al Surface Material (disabled Separate menu for V-Ray materials)

Opacity – Assigns transparent properties to the material, where white is completely opaque and black is completely transparent. Maps can also be assigned to create a material that has a non-uniform opacity.

Diffuse Color – The color of the material. Note: The actual diffuse color of the surface also depends on the reflection and refraction colors. You can use a texture map for the diffuse color.

Texture – Specifies a texture file to be used for the diffuse.

Mix Strength – Specifies a blend amount for the texture map.

Diffuse Strength – A multiplier for the diffuse color.

Diffuse Bump Map – Specifies a texture as the bump or normal map for the diffuse component. The bump effect here is added to the General parameters bump effect. If no map is set in the General parameters or the map there is disabled, the map in this layer still produces its bump effect.

Diffuse Bump Amount – A multiplier for the bump map effect.

Diffuse Bump Type – Determines how the Diffuse Bump Map parameter is interpreted.

Bump map – Applies the map as a bump map.
Normal map in tangent space – Applies the map as a normal map in tangent space.
Normal map in object space – Applies the map as a normal map in object space.
Normal map in screen space – Applies the map as a normal map in screen/camera space.
Normal map in world space – Applies the map as a normal map in world space.
From texture bump output – The map is applied as determined by map type itself.
Explicit normal – Applies the map as an explicit normal.

The AL Surface Material has two reflection tabs with identical parameters for precise control over two types of reflection.

Reflect Color – The reflection color. Note that the reflection color dims the diffuse surface color.

Texture – Specifies a texture file to be used for the reflection.

Mix Strength – Specifies a blend amount for the texture map.

Reflect Strength – A multiplier for the reflection color.

Reflect Roughness – Used to simulate rough surfaces or surfaces covered with dust.

Reflect IOR – The IOR to use when calculating Fresnel reflections. Normally this is locked to the Refraction IOR parameter, but you can unlock it for finer control.

Reflect Distribution – Determines the type of BRDF (the shape of the highlight):

Beckmann – Uses a Beckmann distribution for the reflection.
GGX – Uses GGX distribution for the reflection. The GGX distribution has a longer "tail" compared to the Beckmann distribution.

Reflect Bump Map – Allows the user to select a texture for the bump or normal map for the reflection component. The bump effect here is added to the General parameters bump effect. If no map is set in the General parameters or the map there is disabled, the map in this layer still produces its bump effect.

Reflect Bump Amount – A multiplier for the bump map effect.

Reflect Bump Type – Determines how the Reflect Bump Map parameter is interpreted.

Bump map – Applies the map as a bump map.
Normal map in tangent space – Applies the map as a normal map in tangent space.
Normal map in object space – Applies the map as a normal map in object space.
Normal map in screen space – Applies the map as a normal map in screen/camera space.
Normal map in world space – Applies the map as a normal map in world space.
From texture bump output – The map is applied as determined by map type itself.
Explicit normal – Applies the map as an explicit normal.

The SSS tab has three identical options for subsurface scattering control.

SSS Mix – Enables or disables the SSS options.

SSS Mode – Sets the Sub Surface Scattering Mode.

SSS Density Scale – Additionally scales the SSS radius parameters. Normally, the material takes the scene scale into account when calculating the subsurface scattering effect. However, if the scene was not modeled to scale, this parameter can be used to adjust the effect.

SSS Weight – The relative contribution of the shallow scattering layer to the material.

SSS Color – The color for the shallow scattering layer.

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

Mix Strength – Specifies the blend amount of the texture.

SSS Radius – The distance that light is scattered within the shallow layer.

MATERIAL ID

Material Id Enabled – Enables the use of Material ID.

Material ID – The color used by the Material ID render element. You can also use a shader here.

Multimatte ID – The integer ID of the material to be used by the Multimatte render element.

ROUND EDGES

Round Edges Enabled –  Enables the round edges effect, which uses bump mapping to smooth out the edges of the geometry during render time.

Radius – Specify a radius (in world units) for the round edges effect. Since the actual geometry is not being changed and only the normals of the faces are affected, large values may produce undesirable effects.

Consider Same Object Only – When enabled, the rounded corners are produced only along edges that belong to the same object which has the attribute applied. When disabled, rounded corners are also produced along edges formed when the object with the attribute intersects other objects in the scene. 

Corners – Choose which edges are considered in the calculation. Possible options are:

Covex and Concave – Considers all edges. 
Convex Only – Only applies Round Edges effect to edges with convex angles. 
Concave Only – Only applies Round Edges effect to edges with concave angles. 

Reflect Max Depth –  The number of times a ray can be reflected. Scenes with many reflective and refractive surfaces might require higher values to look correct.

Reflect Subdivs – Determines the number of samples when V-Ray is calculating Reflection.

SSS Subdivs – Determines the number of samples when V-Ray is calculating SSS.

Consider All Objects – When enabled, the V-Ray AI Surface considers all intersecting objects with Al Surface when calculating the sub-surface scattering effect to allow for the effect to "bleed through". This option is not available in V-Ray GPU.