This section describes the sample workflow for three of the mental ray for Maya shaders: , , and (for subsurface scattering).
node
In this scene, the bowl is created using the shader. This shader is commonly used for dielectric media such as glass, water, and other liquids.
Sample workflow for dielectric_material
- Open the editor. Under the tab, select . Click on under the section to create the shader.
- In the shader’s , change to 1.65. This is the index of refraction for a typical glass material.
- Click on the dielectric_material1SG node. In the , expand the section. Since photons are used in this scene (for caustics and global illumination, and so on), a photon shader needs to
be added to the shader group. Under the section, click for the attribute and select (under the section). This is the corresponding photon shader for the shader.
- In the , change the for the to also be 1.65. In this scenario, we wish to simulate both the appearance of glass and the caustic effect of glass. Therefore,
thefor the and shaders are set to identical values.
node
The stand of the bowl is created using the dgs_material shader. This shader is commonly used to simulate glossy materials
such as metals, mirrors, glossy paint and plastic, and so on.
Sample workflow for dgs_material
- Open the editor. Under the tab, select. Click on under the section to create the shader.
- Click on the dgs_material1SG node. In the , expand the mental ray section. Since photons are used in this scene (for caustics and global illumination, and so on), a
photon shader needs to be added to the shader group. Under the custom shaders section, click for the attribute and select (under the section). This is the corresponding photon shader for the shader.
Subsurface scattering node
The grapes in this scene are created using the subsurface scattering node. Subsurface scattering is usually used to create
materials that scatter or absorb light internally (rather than reflect light at the surface). Using subsurface scattering,
the grapes in the scene appear translucent and glowing.
mental ray for Maya includes several subsurface scattering nodes, for example, ,, and so on.
simulates subsurface scattering in the most realistic and physically accurate way. Alternatively, misss_fast_* provides a
reasonable simulation of subsurface scattering, but allows for more efficient rendering and is easier to set up.
Sample workflow for shader
- Open the editor. Under the tab, select . Click on under the section to create the shader.
- Since subsurface scattering involves the bouncing of light near the surface, a lightmap must be attached to the shader. In
the editor, click under the section to create the lightmap shader.
- Click on the shader node. In the , expand the section and click for the attribute to create a texture node.
- In texture node’s , check . Change the and to your render size. Change to 32 bits. Enter a file name in theattribute.
- Click on the material and map the shader to its section.
- Increase the number of samples in the section to create a smoother effect. Increasing the number of samples would create more scattering and increase the intensity
of the light gather effect. The scene thus has more glow.
- Tweak the values undercontrol for better results.
Tip
Beginning in Maya 8.5, you can also get the look of subsurface scattering in your scene by tuning the scatter attributes available
in the mental ray section of the , , , , and surface material nodes. For more information regarding these scatter attributes, see Scattering and Work with Scattering.
Scene settings
- should be incorporated in a scene that includes dielectric material. In the window (Window > Rendering Editors > Render Settings), select mental ray as your renderer. Under the mental ray tabs, Features tab, select under to enable the algorithm.
- To incorporate caustics in the scene, the spotlight in the scene should emit photons. Expand the section of the spotlight’s . Check thesection.
- To brighten the scene, increase the and the value in the spotlight’s attribute editor. If you only increase the photon intensity, this may significantly increase your
rendering time. Lowering the exponent value allow you to brighten your caustics without increasing rendering time.
- If you notice blobby caustics on the walls of your Cornell box, tweak the type and sections in yourwindow.