Lighting - Arnold for Katana
Global Light Samples
When enabled, the light sample settings on individual lights are ignored and the overall contribution of all lights together is computed using only the specified number of samples.
It does not apply to environment, directional lights, volumes, and GPU rendering.
Luminaire Bias
Sets a distance offset for shadow rays to prevent a light becomes an occluder itself.
Nested Dielectrics
Enables the nested dielectrics system for IOR tracking in scenes with adjacent dielectrics. Defaults to on.
Stochastic Volume Interpolation
The tricubic interpolation mode of AiVolumeSampleXXX() calls, such as those used by the standard_volume shader, uses a stochastic method of interpolation that greatly reduces the amount of voxel data read in each sample call. This can speed up rendering by as much as 20% in assets such as the WDAS cloud data set.
Note that this technique does not always produce a perfectly matching image as a result, and can be toggled via the stochastic_volume_interpolation render option (default is on).
Ray Depth
Ray Depth allows you to configure settings that limit the ray recursion based on ray type. Higher values will increase render time.
Environment
Background
You can drag a material location to this parameter, which material defines the shader to be run when rays hit the background.
Note that it is preferred instead to use a skydome_light instead to generate a background, and there is an additional shader slot for background rays there.
Note that KtoA defaults to a background that is invisible to camera rays, as that is the typical workflow for images with compositing as their destination.