UE5 Lightmap Density artefacts and issues with baked lighting

Development Rendering
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1

Hey,

I have some issues with building lights in UE5. I imported a working scene from UE4 (although I have the same issues when making the same scene from scratch, even though it works in UE4) and I’m trying to make it work in UE5. When building the lights in UE5 however, I get all kinds of lighting issues even though nothing has been changed after the import to UE5. Lumen is disabled.

The issue is that when using the lightmap density view mode there are all kinds of black artefacts that look like Z-fighting even though there isn’t any overlapping geometry.

Below is a short video of the issue. It looks normal at first with the baked lighting from UE4, but building it again creates all kind of lightmap issues.

I haven’t had this problem in UE4, any ideas why UE5 behaves like this?

2

It is a known issue.

You can vote on this and perhaps it will be fixed soon.

2 Likes
3

Ah, I see. Thanks for the answer, I voted on it.

4

For anyone else seeing this post, I replaced the LightMapDensityShader.usf file with this from the UE GitHub and it fixed the problem

https://github.com/EpicGames/UnrealEngine/blob/c18b86b59ecd13f3c6caedb550355b8406f5699e/Engine/Shaders/Private/LightMapDensityShader.usf

3 Likes
5

YOU FREAKING LEGEND.

You have no idea how much headache this bug has caused me. I was crushed when I found out it wasn’t fixed in 5.2, but now I can even use it in 5.1 :smiley:

6

Hi, can you update the file for 5.2, because the link is no longer working, unfortunately. Thank you very much in advance

7

Seeing this issue again in 5.2 on the ThirdPersonMap base assets.

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Any solutions?

8

I get this bug in 5.1, i haven’t updated yet but it says the issue has been fixed on 5.3. Fingers crossed, because it’s pretty annoying and borderline bad for your brain to see flashing like this for too long.