UE 5.7.4 - Lumen - As a new object appears on screen from behind another, black lines appear

Development Rendering
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1

Default lumen settings, the issue is most visible in a brightly light space.
When you move around, in the viewport or in-game, there are black lines that appear when distance objects appear on screen from behind another.

Its mostly when a new object appears on screen, maybe when lumen calculates? To show that it is mostly when a new object appears on screen, I added different materials to some wall meshes behind the pillar in this test scene.

The youtube video I linked shows this, but here are some gifs and screenshots from the same video: https://youtu.be/torPbGRePUM

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LumenBlackLine

2

what’s the color of your skybox? this looks like an occlusion culling artefact with a black skybox.

3

Might need to make the bounds of your wall pieces 1.25x larger just to make sure they don’t get culled.

4

This is exactly what it is. I Had a black skybox

5

I have increased the positive & negative bounds extension values quite a bit and the artifact is still there

6

Yeah I remember there were these artifacts all over the place with non-nanite geometry because it uses occlusion querries based on bounding boxes on next frame, and i too had no luck with that occlusion working properly. Nanite does not have that issue for me because it is self occluding based on actual triangles. Maybe it was better with baked lights that had visibility baked, i don’t know.