RTAO Culling
This page describes parameters under the "Ray Tracing Culling" foldout that are specific to RTAO mode.
It is recommended to use the Hardware Ray Tracing Scene debug mode to visualize the changes introduced by the culling settings.
Cull Alpha Cutout
Culls all geometry with Alpha Cutout properties from the ray tracing acceleration structure, making it invisible to ray tracing. This can be used to speed up ray tracing in Native mode (alpha-cutout geometry is notorious for slowing down ray traversal), or to exclude it from Inline ray tracing to avoid artifacts stemming from screen-space alpha cutout evaluation in this mode.
Performance impact: beneficial
Cull Backfaces
Specifies whether rays can collide with the backfacing sides of polygons. This option is global and affects all surfaces, ignoring the "Double-Sided" material parameter. Disabling this option may slightly speed up tracing, as rays have a higher chance of finding hits earlier if they can collide with both sides of polygons. Enable this option if there are issues with non-closed geometry.
Performance impact: moderate, disable if not needed
Culling Mask
Allows culling objects from the ray tracing acceleration structure on a per-layer basis, making them invisible to ray tracing.
Alternatively, individual meshes can be culled by using the Ray Tracing parameters in the Mesh Renderer component, where Ray Tracing Mode can be set to Off.
Culling Mode
Specifies which technique is used to cull geometry from the ray tracing acceleration structure.
None: no culling is performed, all objects are included in the ray tracing acceleration structure.
Sphere: all objects outside a bounding sphere centered around the camera, with radius controlled by the Culling Distance parameter, are culled.
Solid Angle: allows ignoring small or distant geometry based on its projected solid angle, specified by the Min Solid Angle parameter.
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