Hey all, with the new UE5.4 update i decided to try the new improvements to hardware raytracing, specifically the pathtracer. In the past it was difficult to render large scenes with many static mesh instances. while foliage instanced static mesh culling DID cull instances, it also resulted in flickering instances, seemingly created by a random flipping of the raytracing world normal. I was hoping this would have been solved in 5.4, however the issue still persists. I am attaching videos depicting this behaviour. To reproduce, a blank project with pathtracing enabled. Simple foliage paint of the default cube static mesh.
The videos each depict 3 passes: Raytracing Debug World Normal, Raytracing Debug Instances, and finally the pathtracing pass.
disabling culling fixes the issue but renders all instances, with following cvars:
r.RayTracing.Geometry.InstancedStaticMeshes.Culling 0
Enabling instance culling (angle based culling) results in culled instances but flickering instances:
r.RayTracing.Geometry.InstancedStaticMeshes.Culling 1