It looks like the DistantScreenTrace(...) in LumenScreenTracing.ush reports a false positive hit in the dark regions.
Using screen trace visualization reports the distance in these regions as 65535.

Steps to Reproduce

1. Open test project from Licensee:
2. Observe dark artifact on the reflective rectangle when nothing else is present in screen space
3. Turn off “r.Lumen.Reflections.DistantScreenTraces” and observe that the problem is no longer occurring
4. Alternatively, change the cvar: “r.Lumen.Reflections.DistantScreenTraces.MaxTraceDistance” to a lower value like 10000 and observe that the problem is no longer occurring.

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-200202 in the post.

Login to Vote

ComponentUE - Graphics Features - Lumen
Affects Versions5.3
Target Fix5.4
Fix Commit29720584
Main Commit29731754
CreatedNov 10, 2023
ResolvedNov 14, 2023
UpdatedDec 11, 2023