For some reason, the lightmaps just will not work correctly no matter what i do. I am using modular assets, these are just simple planes which were quickly made in blender. When building the level, they have visible seams between them, and to fix this i changed the lightmap scale to 0.1 . Now this noise effect has started happening, and no matter what settings i mess with it will not go away, unless i set the scale back to 1, in which case the squares will just all be shaded with one shade each. I am using static meshes as modular assets. The wall is just a solid white material, all that noise comes from the lightmap. It seems to only happen when there are shadows being cast on surfaces, no surfaces to cast on will mean no noise.
What are the skylight settings? Is there a directional light? If yes, what is its settings? It looks like a problem with shadowing, so it could easily be a post process volume issue. Check that too, and try modifying shadow settings, especially mesh distance fields, ray tracing, and cascaded shadow maps.
There are no directional lights or outside light whatsoever. It is a completely indoor scene. I don’t think distance fields are even enabled. I assumed post process volumes didn’t affect light baking. There are no post process volumes though, and the grain is definitely part of the lightmap, not a post process.
A screenshot of your lightmass settings for this build would be really helpful!
…we don’t really know anything about your lighting!! What lights are you using?
What I see on the attachment is: lack of samples!!
If you go with 0.1 level scale and 0.6 smoothness ALL the seams should disappear!!
The grainy look: quality!! Production mode + 8-10 for quality and those should disappear too!
If I may: you should read more about lighting in Unreal!!
The problem might be overlapping shadow penumbras, with the artifacts resembling insufficient interpolation in the lightmap(s). The spots / grains appear to correspond to the density levels of lighting samples in a volumetric lightmap 3D grid. This is where in the corner seams between surfaces (floor to wall seams, and in the tri-plane corner near the lower center of the screenshot) the lighting samples are denser in the 3D volumetric lightmap, and on the surfaces of the walls it is far less dense with larger samples. It has something to do with the VLM. Visualize that in the Show button in viewport, and see if there’s more information to be gleaned from the data and the visualization of the grid. You can click on each individual sample and get data, I think. Probably need to look up how to do it all.
