ilrOccSampler

The ilrOccSampler material performs occlusion sampling.

Important: Turtle does not load automatically when running Maya. To use Turtle, activate Turtle.mll in the Plug-in Manager.

Occlusion Type

Type: The type of occlusion. It can be set to either Ambient Occlusion or Reflective Occlusion.
Output: The output from the node.

Occlusion: The sampler outputs the occlusion value in the color channel.
Vectors: The sampler outputs the bent normal (if Bend Normals is enabled) in the Color channel and the occlusion value in the alpha channel.
Vectors and Occlusion: The sampler outputs the normal in the color channel and the occlusion value in the alpha channel.
Environment * Occlusion: The sampler outputs the occlusion value multiplied with the environment map in the color channel. If Reflective Occlusion is used, the reflection direction is used instead of the surface normal as the Vector.

Coordinate System: Lets you select the coordinate system (World Space or Tangent Space) to use when saving vector information to file.
Use Face Tangents: If Tangent Space is selected, enabling Use Face Tangents tells Turtle to calculate face tangents instead of using the interpolated vertex tangents.

Min Color/Max Color: The sampler interpolates between the two colors according to the occlusion value.
Bump Mapping: The bump channel on the occlusion sampler.
Environment: The environment map channel.

Min Sample Rays: The minimum amount of rays that will be sent by the sampler.
Max Sample Rays: The maximum amount of rays that will be sent by the sampler.
Core Angle: Decides how much of the hemisphere that is to be sampled. 180 degrees covers the entire hemisphere.
Max Distance: Sets the max occlusion distance. Beyond this distance there is full visibility. Hence it also controls the maximum distance an occlusion ray is traced. If set to 0.0 the value is calculated according to the size of the scene. For closed scenes this value needs to be set according to some fraction of the scene size, otherwise there will be full occlusion everywhere.
Contrast: Can be used to adjust the contrast for ambient occlusion. Increasing this value will make dark surfaces darker and bright surfaces brighter.
Scale: A scaling of the occlusion values which can be used to increase or decrease the shadowing effect. By increasing this value you will boost the shadowing effect.
Self Occlusion: Sets how to handle self occlusion, i.e occlusion rays intersecting the same object as they are emitted from.

Disabled: Objects does not cast occlusion on itself.
Environment: Hits on the same objects are treated as misses, i.e the ray is terminated and the environment is set.
Uniform Sampling: Sets whether uniform sampling should be used. If disabled cosine weighted sampling is used, where more rays are concentrated near the normal of the surface. If uniform sampling is used all surfaces around the shading point gives an equal amount of occlusion. If cosine weighted sampling is used, surfaces in front of the shading point gives more occlusion than surfaces to the side.

Obey Transparency: If enabled, the sampler will consider the transparency of the surface hit by the occlusion ray and continue if it is transparent.
Enabled: Objects occludes themselves normally. This is the default method.
Bend Normals: If enabled, Turtle will calculate the most unoccluded direction. Bend Normals does not work with Adaptive Sampling.

Enable Adaptive Sampling: If adaptive sampling is enabled, the occlusion sampler will not sample every point. Instead it will interpolate neighboring points much like final gather.
Accuracy: Controls number of samples created. Increase to force more samples and get higher quality.
Smooth: Radius of smoothing filter.
Use Occlusion Map File: Enables Turtle to save occlusion samples to file and reuse them in subsequent renders.
File Name: Name of file to save samples to.