Thanks for sending me your scene. I investigated what’s happening. This is a really extreme lighting setup, with a very bright skylight set to 50 on intensity, and it gets blocked very abruptly in a line. Even the path tracer has a line:
But it gets way worse due to Lumen’s Radiance Cache. I’m afraid we don’t have a solution to this for 5.0 release. Here are some workarounds you can try though:
- Shift the entire level up or down until the dark line disappears. This changes where the Radiance Cache probes are relative to the geometry. Ugly, I know.
- Raise r.Lumen.ScreenProbeGather.MaxRayIntensity to 100, this fixes the clamping of energy that Lumen is doing
- Disable Lumen’s Radiance Cache with r.Lumen.ScreenProbeGather.RadianceCache 0
After shifting the level, I can get decent results even with Radiance Cache on:
Also, this level has content that Lumen cannot support. Check the Lumen Overview visualization, all of the pink means uncovered surfaces that Lumen can’t bounce lighting off of.
This happens because the level was not built modularly.
From the doc:
Only meshes with simple interiors can be supported — walls, floors, and ceilings should be in separate meshes. Importing large, single meshes are not expected to work with Lumen.
It sucks that Lumen has this content limitation, but it’s what allows us to make it possible in realtime. Fixing that will solve some of the missing bounces, and some of the leaking.