Lumen (non-raytraced) is it screenspace for non-RTX?

Development Rendering
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I’ve noticed something curious with a realtime interactive project I am playing with in UE5 and using Lumen for the GI.

I am finding that depending on where I look in my scene the GI is fading in an out (light to dark) almost as if it is a screenspace effect.
Having watched the livestreams I had thought Lumen was a combination effect and not solely relying on screenspace like the previous GI method in 4.26.2.

Does anyone know if this is expected if not using hardware raytracing with Lumen?
I have confirmed Lumen is in fact working by toggling it in the Post Process volume, I am just surprised to see it fade in and out as if it is screenspace effect.

Note: The scene in question is a dim dirty corridor and is actually only lit by a single point light behind a doorway (so to speak) so no skylight and not atmospheric lights (as the outside cannot be seen at all)

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Read this: Lumen GI is screen space? - #6 by pezzott1

Hope it helps.

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Thanks @pezzott1 I had just found that, a appreciate you popping it in the post for others :slight_smile:

I am thinking my issue must be somehow related to Eye Adaption or some sort of auto-exposure despite even having my PP volume set to Manual exposure, the Lumen GI just still “sort of” fades a bit as if it was SSGI…

Might need to go back to the drawing board and relook at the live streams LOL

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If you are willing to share a few screenshots, perhaps other and I could be of more help.

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its even in the docs, lumen has a first pass that is screen bound or whatever they are calling it