Please note that this documentation space offers information for V-Ray 3.6! For most up-to-date documentation, refer to V-Ray Next for Modo help.

This page provides details on the V-Ray alSurface material.

 

Page Contents

 

Overview


The V-Ray alSurface 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 Path: ||Shading viewport|| > Shader Tree > Add Layer button > V-Ray Materials > V-Ray alSurface

 

Parameters



Bump rollout



 

 

Bump Amount – The maximum amount of bump.

Bump Type – Defines how the bump input is read by the material. Bumpiness can be adjusted specifically for the Diffuse and Reflection colors. See the Bump Type Example for more information.

Bump Map – Uses a bump map to determine the bump effect on the material. Note: When using a Gradient or Constant texture for val Bump Map, adjust the Color output for the effect to be seen. Adding a map to the Bump can be done from the Shader Tree under Material Effect > VRay alSurface Channels > val Bump Map.
Normal Map in Tangent Space – Uses a tangent normal map to determine the bump effect on the material. The map is created through the Render > Bake from Object to Selected Texture option and setting the texture to normal map.
Normal Map in Object Space – Uses an object space normal map to determine the bump effect on the material. This map is created through the Render > Bake from Object to Render Outputs option and setting the render output to shading normal.
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. This map is created through the Render > Bake from Object to Render Outputs option and setting the render output to shading normal.
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 and Opacity rollout





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 in the Shader tree with a vmtl Opacity effect for the map. When a map is used, white is completely opaque and black is completely transparent.

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

Diffuse Strength – A multiplier for the diffuse color.

Diffuse Bump Amount – A multiplier for the bump map effect on the diffuse color. Adding a map to the Diffuse Bump can be done in the Shader Tree under Material Effect > VRay alSurface Channels > val Diffuse Bump Map.

Diffuse Bump Type – Bumpiness can be adjusted specifically for the Diffuse color. This parameter defines how the bump input is read by the material to influence the diffuse color. See the Bump rollout Bump Type for more information on bump and normal map types.

 


 

Example: Bump Types

 

Note the difference between layer types Diffuse Bump Type and Bump Type. 

 

 


Bump Map (with bump effect seen over reflection map)


Diffuse Bump Map (with the bump seen under the reflections)

 




 

Reflection rollout


The alSurface Material has two reflection rollouts 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.

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 Beckmann distribution.

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

Reflect Bump Type – Bumpiness can be adjusted specifically for the Reflection color. This parameter defines how the bump input is read by the material to influence the reflection. See the Bump rollout Bump Type for more information on bump and normal map types.

 

SSS rollout



 

 

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

SSS Mode – Sets the Subsurface Scattering Mode.

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

SSS 1 Color – The color for the shallow scattering layer.

SSS 1 Radius – The distance that light is scattered within the shallow layer.

SSS 2 Weight – The relative contribution of the medium scattering layer to the material.

SSS 2 Color – The color for the medium scattering layer.

SSS 2 Radius – The distance that light is scattered within the medium layer.

SSS 3 Weight – The relative contribution of the deep scattering layer to the material.

SSS 3 Color – The color for the medium deep layer.

SSS 3 Radius – The distance that light is scattered within the deep layer.

 



Example: Subsurface Color


This example demonstrates the effect of the Subsurface color parameters. Diffuse and Reflective parameters have been set to a middle grey.

 

 

 


SSS parameters

 

Render

 

 

 

 


SSS parameters

 


Render

 

 

 


 

Options rollout



 

 

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.

 

V-Ray Mtl Common


The V-Ray Mtl Common tab includes rollouts like Layer and Bump and Displacement, which include settings that are general among many V-Ray (and Modo) Materials. For more details, please see the Common V-Ray Material Attributes page.