With UE 5.1, a simple scene with HDRI Backdrop and Lumen results in broken, incorrect lighting. This is a regression from 5.0.3 where everything works as expected.
Simple test scene:
HDRI Backdrop with cubemap property under HDRI settings set to /Engine/EngineResources/GrayLightTextureCube
Some meshes from Engine content.
Global Illumination set to Lumen (Surface Cache for reflections)
5.0.3 result
5.1 result (in editor)
It gets a little lighter in PIE (but still completely broken)
Isn’t this the scaling issue? Like does it work when you set hdri skylight scale to something like 1500 or more?
What do you mean scale? I set it to uniform white cubemap for a test, but it behaves the same way with any HDRI cubemap.
It also works fine on 5.0.3.
The size on hdri backdrop, try 15K or more.
Well, your suggestion seems to work, it looks much closer to expected result.
In my original post I used exactly the same scene on both 5.0.3 and 5.1, and while it worked fine on 5.0.3, it resulted in weirdness on 5.1. So something did change in 5.1, and now that I think about it, the default size seems way to small (as in it would clip with most things in a regular scene). So it remains a mystery to me why it worked at all before.
I have more troublesome scenes with HDRI on 5.1, so I will do more testing to see if increasing the size fixes all these issues. In one of them, for example, the character is all black on 5.1 but works perfectly fine on 5.0.3.
Thank you very much for your help.
I have the same problem, but did you notice that is working perfectly with path tracing ?
If it’s a size problem why is it working with path tracing?
Same issue here, increasing size to 1500 seems to fix it.
5.0 was quite broken, but 5.1 is even more. As the communication and feedback exchange with the community is inexistent, this seems to be the norm.
I have the same issue, the HDRIbackdrop does not lightning the scene, it is just visible in reflection… With 5.0.3 the HDRI works like a charm. In UE 5.1 is broken. If I put the size to 15000 the reflection of HDRI is blurry sh#*… Did you find any solution for this?
I found the solution on a reddit post to this issue. You have to disable “Visible in raytracing” in the geometry component of the HDRI Backdrop. This solved it for me.
Yes, it can help lighting the scene, but your reflection going to be bad after that. You gonna lose your high-quality reflection then… :\ so there is no good solution, just something that can help a little bit but it’s so annoying, what works in 5.0.3 doesn’t work in 5.1.1 UE.
Still broken in 5.2, same issue with lumen and increasing size can solve it but totally unusable for rectangular hdri and backdrop as box or boxSharp. You don’t want a room that’s 150 miles.
I made some test 5.2, scaling size, is not helping, no lighting from the hdr
I am also struglling to get HDRi to work in UE5.2 with Lumen, it is only working for Pathtracing:
I tried scaling up both size and intensity, disabling HDRi skydome mesh to be invisible to raytracing. Hardware raytracing in project setting on or off, Raytraced sky on or off. Changing the size, doesn’t help and even if it did, it takes away the control of being able to size it for artistic direction.
Somehow by accident I made it work with minimal changes by changing the mesh
This is the only change that just works without fiddling with anything else. As a bonus, the background is no longer distorted.
With that, both Lumen and path tracing look the almost the same.
Lumen:
Path tracing:
This is on 5.3.1
Hope this helps.
Hello ! My 2 cents here just in case. I had same issue, hdri backdrop sometimes work, and often not. I raised the hdri backdrop size as well AND, in the skylight contained into the hdri backdrop, i raised the sky distance threshold to 15000 as well. This one makes it work instantly, and consistently. Cool. i raised the cubemap resolution of the skylight to 2048 to get a more precise hdri conversion into lighting. Hope it helps !
Yes same issue and I was trying to fix it all afternoon and I was pulling out my hair. Changing it to a cube instead of a sphere worked!
I want to add one last note, if SM_ColorCalibrator is used, the chrome sphere has a Roughness of 0.1; You will never get good reflections. It should be at least 0.05. I hope it helps you!!!
