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This page provides information on the BRDFAlSurface material node.

Overview

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.

UI Paths

Node

The BRDFAlSurface node provides inputs for controlling various material properties. They correspond to parameters in the section below.

Overall

This section allows you to control the swatch for the VRayAlSurface material.

Bump Type – Defines how the bump input is read by the material.

Bump Map – Uses a bump map to determine the bump effect on the material.
Normal map in tangent space – Uses a tangent normal map to determine the bump effect on the material.
Normal map in object space – Uses an object space normal map to determine the bump effect on the material.
Normal map in screen space – Uses a screen space normal map to determine the bump effect on the material.
Normal map in world space – Uses a world space normal map to determine the bump effect on the material.
From texture bump output – Uses the texture bump output to determine the bump effect on the material.
Explicit normal – Uses the mesh's set normal to determine the bump effect on the material.

Bump Amount – The maximum amount of bump.

Opacity – Assigns transparent properties to the material where 1.0 is completely opaque and 0.0 is completely transparent. Maps can also be assigned to create a material that has a non-uniform opacity. When a map is used, white is completely opaque and black is completely transparent.

Diffuse

Strength – A multiplier for the diffuse color.

Color – The color of the material. Note: The actual diffuse color of the surface also depends on the reflection and refraction colors.

Diffuse Bump Type – Defines how the bump input is read by the material.

Bump Map – Uses a bump map to determine the bump effect on the material.
Normal map in tangent space – Uses a tangent normal map to determine the bump effect on the material.
Normal map in object space – Uses an object space normal map to determine the bump effect on the material.
Normal map in screen space – Uses a screen space normal map to determine the bump effect on the material.
Normal map in world space – Uses a world space normal map to determine the bump effect on the material.
From texture bump output – Uses the texture bump output to determine the bump effect on the material.
Explicit normal – Uses the mesh's set normal to determine the bump effect on the material.

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

SSS Mix – Mixes between the Diffuse component and the SSS component.

SSS Mode  – Sets the algorithm for calculating Sub Surface Scattering.

Diffusion – The default mode that preserves details well.
Directional – Similar to Diffusion, but includes single-scattering approximation for additional realism and detail.

SSS Density Scale – Additionally scales the SSS Radius parameters. Normally, the material will take 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

The AL Surface Material has three SSS rollouts with identical parameters for precise control over three types of subsurface scattering.

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

Color – The color for the shallow scattering layer.

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

Reflection

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

Strength  – A multiplier for the reflection color.

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

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

BRDF – 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 Beckmann distribution.

Index of Refraction – 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.

Bump Type – Defines how the bump input is read by the material.

Bump Map – Uses a bump map to determine the bump effect on the material.
Normal map in tangent space – Uses a tangent normal map to determine the bump effect on the material.
Normal map in object space – Uses an object space normal map to determine the bump effect on the material.
Normal map in screen space – Uses a screen space normal map to determine the bump effect on the material.
Normal map in world space – Uses a world space normal map to determine the bump effect on the material.
From texture bump output – Uses the texture bump output to determine the bump effect on the material.
Explicit normal – Uses the mesh's set normal to determine the bump effect on the material.

Bump Strength– A multiplier for the bump map effect on the reflection.

Sampling

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.

Reflection Subdivs – Controls the quality of glossy reflections. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results.

SSS Subdivs – Controls the quality of the subsurface scattering effect. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results. Note: In order to use the Reflection Subdivs and SSS Subdivs parameters, the Use local subdivs option in the DMC Sampler must be updated. Otherwise, glossiness subdivs are controlled globally, which in most cases produces a good balance between render quality and performance.

Example: Sub Surface Color

This example demonstrates the effect of the Sub-surface color parameters. Diffuse and Reflective parameters have been set to a middle gray. The SSS Density Scale has been set to 0.04.