What you're seeing
Shadows become box-like or show bias errors where the receiving surface is nearly parallel to the light direction.
Likely causes
- A shallow light angle stretches a shadow across too much projected space.
- A very large local light exhausts its available virtual resolution.
- A narrow camera field of view exhausts directional clipmap resolution.
Check in this order
- 01Move the light angle in a controlled test and confirm that the artifact tracks projective stretching.
- 02Use a Directional Light instead of a very large local light when the lighting design allows it.
- 03Reduce unnecessary local-light coverage.
- 04Apply a one-step resolution LOD bias only as a measured quality and performance test.
Views and commands
Directional resolution test
r.Shadow.Virtual.ResolutionLodBiasDirectional -1Doubles directional-shadow resolution relative to a bias of 0, with added cost.
Local resolution test
r.Shadow.Virtual.ResolutionLodBiasLocal -1Doubles local-light shadow resolution relative to a bias of 0, with added cost.
VSM clipmaps
View Mode > Virtual Shadow Maps > Clipmap/Mip LevelShows which directional clipmap or local-light mip supplies each region.