I do not understand why some of the valid probes are so dark and are giving dark patches in the ceiling of my mesh. The mesh is “inside out” in that the collider polygons are facing inwards. I have tried reading the “Fix documentation” here (on HDRP but advice is identical) and here but the tips as…

Ah ha! Sorry, I didn’t realise that it was private to start with. That does make sense. Unity have repro’d it and confirmed it is a bug. While bugs are sad, I’m glad our hard work paid off! Here is the tracker link (I checked it this time!) https://issuetracker.unity3d.com/issues/dark-patches-are…

More experimentation but still no success! I’ve made the walls 2 units thick, reduced the size of the probes down to 0.5 and I can see by clipping the camera that the probe validity is correct: probes inside the mesh are red and green outside: [image] However the problem still remains. [image] …

To better define the problem, I have greatly simplified the scene. I started with the Unity URP 3D scene. I added APV and removed environment lighting I have a solid convex hull mesh with Unity Lit shader and a material to make it green I have a grey cube with Unity Lit shader so I could check the…

I still haven’t managed to get this to work. Instead, I have removed any GI contribution from emissive surfaces and put baked spot lights in instead.

Heya. I’m by no means an expert in lighting, but I’ve taken a look at your repro project and have a few comments: Is there a particular reason the convex hull Mesh Renderer is set to Receive Global Illumination from Light Probes instead of Lightmaps? I was under the impression that you would norm…

Thank you so much for your very detailed reproduction! I’ll raise a bug. The reason that I’m avoiding using lightmap textures is that quite a lot in my game is dynamic. I was going to experiment to see if I could do something arty and clever with textures but this issue really sucked all my energy …

For anyone following along, bug report is here: Jira Service Management

Fair, fair. I’ve done a bit more research and it seems my info about when to use Receive GI from Light Probes vs Lightmaps is outdated when it comes to APV - because it has the Lighting Scenarios feature but it only affects probes and not lightmaps. So it is indeed viable to use Light Probes for sta…

Ah, hello there! I think I read your post when I was researching. I believe we all thought we were doing something wrong!

Sweet, upvoted. Hopefully it gets fixed soon - seems like baked emission would be a pretty crucial part of many lighting setups! And good luck with the future lighting stuff, I know how much of a pain it can be :sweat_smile:

How to remove dark patches in URP APV Global Illumination?

Unity Engine

filibis February 27, 2026, 1:02pm 10

Thank you for reporting this! I had this very similar issue that I couldn’t figure out, and I always thought I was doing something wrong, but it was most probably a bug all along!

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How to remove dark patches in URP APV Global Illumination?

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