Enable/disable contribution from light that scatters exactly once in the surface. Certain types of surfaces (such as skin) gain little contribution from single scattering and so disabling this option will reduce computation time with little impact on accuracy.

When this option is on, the node uses a BRDF to approximate the scattered rays. This option is faster but less accurate.

The number of samples for single scattering. Increase this option to decrease noise at the expense of slower shading.

Enable contribution from light that scatters more than once in the surface. For low albedo materials (low Diffuse Color), multiple scattering contributes little to the image and can be disabled to reduce computation time.

Controls the way in which multiple scattering is computed. Normally you should use the Local And Global mode if you are planning to use a point cloud, and Ray Tracing to compute multiple scattering without a point cloud. Using a point cloud can produce smoother and faster results, but it requires precomputation of a point cloud and computation of irradiance for each point in the cloud (once per render).

The quality of the light sampling used for the point cloud contribution when Model is Global Point Cloud or Local And Global. This value is also used to control the number of ray samples when the Model is Ray Tracing.

The quality of the light sampling used for the BRDF contribution when Model is Local BRDF or Local And Global. The local quality can be an order of magnitude lower than the global quality without adversely affecting the outcome, allowing faster evaluation.

Use a BRDF approximation to compute multiple scattering for secondary rays. Turn this option on for faster but less accurate results.

Controls the contribution from the local BRDF in the Local And Global model. Smaller values will reduce the area of local integration, which will reduce sharpness and possibly introduce low frequency noise. Higher values will increase sharpness and reduce low frequency noise.

Controls how the shader generates a point cloud. The simplest option is to select Generate At Render Time. This will create a new point cloud for every render. To reduce computation time, you can first use Write To File mode and then re-use the point cloud using Read From File mode on subsequent renders. This is also the recommended approach when rendering animations because the shader will smoothly interpolate the point cloud across frames. The exception to this is when the model’s topology changes (two joined polygons are separated, for example). In this case, a new point cloud must be generated. Note that in Write To File mode, the file will be overwritten if it already exists. Cancelling a render before it completes in Write To File mode may result in an unusable point cloud file.

See managing point clouds for more information.

Controls the file the point cloud is written to/read from when Point Cloud Mode is Write To File or Read From File. The point cloud is based on surface UVs, so it is not necessary to write a new point cloud file for each frame unless the topology of the model is changes.

Writes point positions, normals, and areas to the point cloud. This may speed up shading, but only for static geometry and a static camera. If the geometry or camera moves (transforms), you should either turn this option off or regenerate the point cloud.

Writes light information to the point cloud. This can speed up shading for point clouds with many points, but only for static geometry and a static camera. If the geometry or camera moves (transforms), you should either turn this option off or regenerate the point cloud.

Turn this option on to have the node automatically decide how many points to use in the point cloud based on the scattering properties of the surface. You can then use the Auto Size Factor parameter to scale that number. Turn this option off to set the number of points in the cloud manually. Smaller point clouds are faster to generate and render, so reducing the size can speed up the render.

Lets you scale the number of points the node chooses for the point cloud when Auto Point Cloud Size is on.

Number of points to generate in the point cloud when Auto Point Cloud Size is off. Higher point counts will increase quality at the expense of computation time.

Caches results of multiple scattering calculation on the point cloud’s points, and then interpolates between those cached values to compute the value at a sampled point. This is much more efficient, but less accurate, than recomputing scattering for each sampled point on the surface.

When this option is enabled, the Multiple Scattering Color (Global) output of this VOP must be exported via a Parameter VOP. To do this, create a Parameter VOP, set its Parameter Type to Color, set its Parameter Name to multiglobclr, set Export to Always, and connect its input to this VOPs Multiple Scattering Color (Global) output. Alternatively, use the right click Create Export Bindings menu item on the physicalsss node to create exports for each output.

Number of point cloud points to filter (see Filter Multiple Scattering). Increasing the point count will produce a more blurry result, while decreasing the point count will produce a more blotchy result.