Category: mental ray > Material Phenomena
Shader Family: Material Phenomenon
This phenomenon automatically (unless explicitly specified) generates the required lightmaps, fills in the lightmap data, and shades the objects as a general, translucent object with subsurface scattering. The scattering is divided into two parts, one for the front side of the object and one for the back. It is connected directly to the Material node's Material port, which prevents the material node from accepting other connections.
The shader works by layering several light contributions on top of each other (see misss_fast_shader for details) to get a final result. What is important to keep in mind are these rules of thumb:
The bump map only affects the specular and diffuse_color layers. The subsurface scattering happens below the surface and is oblivious to the surface having bumps.
The overall_color affects all of the diffuse contributions, but not the specularity.
For more information about building subsurface scattering effects in the render tree, see Fast Subsurface Scattering Effects.
To simulate human skin, you can use misss_fast_skin_phen which are specialized and more complex variants of misss_fast_simple_phen.
Name |
The name of the shader node displayed in the render tree. Enter any name you like, or leave the default. |
lightmap depthmap |
Not normally used because this phenomenon automatically generates lightmaps. These are special parameters the shaders use to communicate the name of the automatically created lightmaps between themselves. Expert users can pass writable textures and leave the lightmap_group and lightmap_size parameters undefined. You can Edit the image clip, or get a New image clip from file or from source. For more information about working with images, see Managing Image Sources & Clips [Data Exchange]. |
lightmap_group |
The name of the scatter group. A lightmap and depthmap pair are created internally and given this name. All objects that should scatter light into each other should be in the same scatter group. To conserve memory, use as few scatter groups as possible. A character's hands, face, etc. can use the same scatter group; even hands and faces of different people. In general, different scatter groups should be used only when using the same group would cause visible problems due to objects incorrectly scattering into each other. Two characters shaking hands, for example, would need to have their hands in different scatter groups. |
lightmap_size |
Specifies the size of the lightmap, expressed as a percentage of the final rendered image resolution. Normally, this value should not need to be higher than 50%. However, should the rendered image still contain artifacts, you can set it higher than this. |
lightmap_samples |
Specifies the number of lightmap samples considered by each rendered ray. Generally, this should be set to a power of two (16, 32, 64, 128, etc.). Subtle scattering effects typically require few samples. However, as you begin to increase the front and back scattering radii, or the back scattering depth, you will need to increase the number of samples to avoid speckling in the rendered image. |
bump |
Pick the shader that perturbs the normals. The shader's color output (if any) will not be used. |
mode |
The mode selector for the light list. For more information, see Setting the Light List Mode [Direct Illumination]. |
Creates a light list to specifiy which lights should produce the effect. For more information, see Using Light Lists [Direct Illumination].
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