What is going on here? It’s just a simple emissive material, and only shows up in the packaged game.
Did you mark it as a light source?
Have you checked the room in the Lumen Scene view?
small emissive meshes are not well represented in the lumen scene and can miss the probe evaluation/propagation/update phase on the lower light grid sizes. you should put an analytical light in the same spot. or if you use megalights 6 area lights would be the “proper” way to reproduce the shape and cast of the lighting and shadows.
I have checked it as a light source, but did nothing. I see the same splotches in Lumen scene view, not sure what to check here.
Interestingly, this only happens on medium scalability.
The “medium only” part, plus the same blobs in the Lumen Scene view, means the material is fine and the surface cache is not. Medium scalability drops Lumen onto a much coarser card atlas (software Lumen, fewer cards, lower texel density). A small emissive mesh then covers a handful of giant texels, which is the splotch. The editor is usually on Epic, so the same mesh looks clean there, and a packaged game comes up on Medium. Marking it as a light source only adds it to the injection list. It does not give the mesh more cards, so the splotch stays.
On that static mesh, raise the Lumen card resolution (Max Lumen Mesh Cards, and the minimum card size so it is not one card for the whole prop). Then check the Lumen view mode Surface Cache, not only Lumen Scene. If the cards are still huge relative to the mesh, that atlas is the blob you are seeing.
For a build that has to look right on Medium, don’t use the emissive mesh as the light. Put a rect or point light on it and set indirect lighting intensity so Medium’s GI matches, and leave the emissive as the visible glow only. MegaLights area lights are the high-end version of that, but they are not what Medium is running.
I was able to remove the sploches by turnig off “Affect Dynamic Indirect Lighting” in the mesh.
Max Lumen Mesh Cards did nothing.
However, now I’m having another issue where the spotlight that I added to support the emissive material is very sharp against the wall. Something is weird in 5.8, these issues don’t show up in 5.7.
A simple spotlight comparison:
5.7
5.8
Source radius in the spotlight seems to be doing nothing. And this is on all scalabilities.
I have re-installed Unreal, and migrated to a new project, and now all my issues are gone.
Not really sure what happened, I suppose my install was borked or some scalability settings were off on my machine.