The index of the LOD level that contributes to global illumination.
Global illumination systems that select a single LOD level per LODGroup, such as the Unity Compute Light Baker and Surface Cache global illumination, use only the Renderers of this LOD level. Set this to -1 to exclude the LODGroup from those systems. The Progressive Lightmapper ignores this property and always bakes LOD 0. The value must be -1 or a valid LOD level index; setting it out of range throws an ArgumentOutOfRangeException. The default value is 0.