My question is in regards to the how lumen gi appears to fade in or out with camera movement. Feeling as though its screen space based because as a camera moves further away it fades out. With manual exposure in post process.
A fix to stop this seems to be enabling ray traced shadows in the dir light however the look of the lighting is then significantly changed and this creates issues with nanite fallback/normals it seems.
This question seems to have been asked a few times before however the threads either fall unanswered or lead elsewhere.
Has there been any development on this in 5.1 or is there any cvars that help combat this change in gi with camera movement?
I am having the same issue in 5.1 and cannot figure out why. It happens on pockets, such as shelves on the wall lit only by GI.
First I thought it is a geometry problem (model exported from 3ds max), but it behaves the same with native unreal geometry in a clean archviz template with default rendering settings. Materials are simple colours with roughness, albedos are well below 0.8…
Yes. Lumen uses a combination of screen tracing and ray tracing. This is especially true when hardware raytracing is disabled.
Usually when a mesh’s lighting is operating is screen space, its a sign its too small or complicated to get a proper representation in the lumen scene. This is typically indicated by appearing yellow or pink in the visualizer.
In your case, I’m not sure why it is happening because it isn’t debug yellow or pink in the lumen scene. Maybe take a look at the mesh distance fields.
Thanks for the reply, the issue disappeared when I deleted the Sun and Sky actor and placed it in the scene again… strange…
This workaround did not help with my original scene though, which is a house exported from Revit LT to fbx, imported to 3ds max and exported through datasmith into UE. The geometry is full of pink and yellow faces, not sure why, so I am working my way through this first…
Pink = too complex for sufficient card coverage. Try increasing the number of cards splitting the mesh, etc.
Yellow = too small in screen size. Pretty sure there’s a setting that controls how small an object can be before lumen drops it from the scene but I don’t remember off the top of my head.
