This shader allows re-rendering a subset of the objects in a scene, defined by object or material. It is intended for a “quick fix” solution when almost everything in a scene is perfect, but just one object or material needs a small tweak.
To use the Render Subset of Scene/Masking map:
Specifies a material to render.
Determines whether the final gather (FG) preprocessing should apply to all objects, or only those in the subset. Because FG blends neighboring FG samples, a given object might use information in FG points coming from nearby objects not in the subset. This is especially true if the objects are coplanar. Therefore it is advised to let the FG prepass “see” the entire scene.
Turning off this option and creating FG points only for the subset of objects is faster, but there is a certain risk of boundary artifacts, especially in animations. If the scene uses a saved FG map, this option can be left off.