Specifies whether the Editor calculates the final global illumination light bounce at the same resolution as the baked lightmap.
When this is set to None, the Progressive Lightmapper does not filter indirect lighting. When this is set to any other value, the Progressive Lightmapper applies the specified filter kernel to indirect lighting.
This setting affects lightmaps generated by the Baked Global Illumination system. It only applies to the the Progressive Lightmapper.
When Unity serializes this LightingSettings object as a Lighting Settings Asset, this property corresponds to the Filtering > Indirect property in the Lighting Settings Asset Inspector.
Additional resources: Lighting Settings Asset.