Hi, new user here. I’m wondering how I might improve the gi quality of the attached interior scene - which relies heavily on indirect lighting. For some reason the sphere reflects what it looks like in the lumen viewport (blotchy) and not the final lit scene. So…
How can I improve the reflection?
How might I improve the GI so it’s not blotchy?
I’ve tried playing with many settings but can’t pin it down.
Perhaps there’s a single setting that would resolve both?
I’m using the sunsky system and placed rect lights to windows for added light - all moveable.
Lumen reflections set to raytrace in ppv, all project settings setup for raytrace and using RTX 3080.
Curious to know - all my lights are dynamic but if I switch them off my scene is not black. It seems somehow light is being baked. I import via datasmith from revit and when I do it asks if I want to generate lightmaps - so far this has been checked. Should I uncheck? How might I delete all lightmaps from scene now that they have already been created? I’ve checked ‘force no precomputed lighting’ rebuilt lights and restarted but the lightmaps still effect the scene.
But I can tell you that if you turn ALL your lights off and there’s still light, that’s because of auto exposure in the project settings. Turn that off.
Light baking makes shadows, not light. It doesn’t matter if you have lightmaps or not, even baking lighting will have no effect if all of your lights are movable.
Thanks mate - good to know. I might be wrong but I think lumen GI final gather is limited to screenspace. For example, if I quickly move the camera I can see it being solved realtime. Meaning that off-screen is always first-pass gi…
So it seems the reflection is actually true to what is off-camera - blotchy gi.
In the past, I remember using ‘radiosity’ in 3ds max. It’s ancient now but it flooded the entire scene with photons and kind of baked the solution across the scene.
Similarly, is it possible to see decent gi in reflective objects revealing off-screen geometry?
That is somewhat true, yes. Lumen’s high-quality final gather operates via screen-space radiance probes, so you’re only going to get super-polished GI for whatever’s actively on-screen. For off-screen, you’re getting the lumen scene that stores radiance in texture space, and it’ll be significantly lower-res. If you go to the PPV, you should find toggles under lumen that let you crank up the lumen scene lighting quality, which can make a pretty big difference.
The GI blotchiness is pretty much intrinsic to the architecture of lumen at the moment. If/when the lumen team introduces their high end surface cache-less version of lumen, it may change, but there’s no timeline on that feature.
I’ll actually give an addendum: hit lighting for reflections will make directly-lit areas in GI look much, much better. It’s important that they’re in direct lighting else it will fall back to the surface cache, but there are definitely ways of getting high-quality GI in reflections.
Hey, thanks for the info and advice. Appreciate it. ‘Hit lighting for reflections’ certainly helped accuracy of reflection. Ok cool, for the GI in reflections I’ll have a look for ways to improve. Any further ideas on the ways to do this? Cheers
