It appears that LumenScene's Hardware Ray Tracing is causing light leaking into a sealed room (which should be perfectly black).

This bug does not appear to happen on AMD GPUs.

Steps to Reproduce

1. Download Licensee's test project and open on a device with a NVIDIA GPU (see addl. info URL)
2. In the room at an angle, observe massive light leaking
3. In axis-aligned room, observe no light leaking
4. In the room at an angle, remove the plant meshes. Observe that the light leaking stops.
4. Change the material on the plant mesh to something opaque (such as WorldGridMaterial). Observe that the light leaking changes, but remains.
5. Disable “r.LumenScene.DirectLighting.HardwareRayTracing” and observe the leaking stops. (You might need to toggle “r.Lumen.HardwareRayTracing” off then on again to get a full clear of the mesh cards, because it might keep bouncing the previously leaked light around.)
6. Observe that scaling up some of the meshes to ensure that there are no minute gaps does not stop the leaking.

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ComponentUE - Graphics Features - Lumen
Affects Versions5.3.2
Target Fix5.5
CreatedApr 23, 2024
UpdatedApr 25, 2024
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