You still seem to have the same problem I do, with shimmering AA around opacity mapped objects. It wasn’t there in EA2 but is present in P1. I wish I knew how to solve that problem 
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Opened my 4.27 scene in 5 preview 1 and everything is working really great.
The only issue Im having is that I have some flickers with the GI in the Trees Static meshes
Im using the Blackadder trees from Megascans
Also Im using Unreal for rendering footage for production, not for gaming or RealTime visualization, so if there is a solution but will cost me performance, is good for me. I like that in UE5 I can render a frame in 1 min instead of 75 min with Arnold.
There’s only so much you can do, of course, but I’d appeal to you to put the stereo functionality in as soon as it’s practical (maybe at the same time as split screen), and let us developers worry about performance as hardware and tweaking catches up.
will you send me your scene? I’ll dm you my email
For noise in the shadow edge the VSM settings will apply, but for noise in Lumen GI, try this:
r.Lumen.ScreenProbeGather.StochasticInterpolation 0
This will be the default in 5.0 Release
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Is there any plan for lumen to implement multibounce reflections?
It’s on the plan but a ways out, they will be really expensive. The bigger priority is getting reliable Diffuse GI in reflections, right now we can only do that through the Surface Cache, but it doesn’t scale up in quality to ArchVis.
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The issue seems to occur very reliably when lights are placed within ~20cm of surfaces. Making it difficult to get good results out of volumetric scattering from lightsources as the light needs to be placed too far from the emission source to make visual sense:
Ah that’s good that you figured out what the main factor is - the distance of the light to the surface. That’s a pretty severe limitation and one that we’ll work on soon, but I don’t think it will get fixed by 5.0 as we’re just running out of time.
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Is it related to the distance of the light to the surface, like in Arkiras’s post? If you push the spotlight away from the surface when you place it, does that make the GI reliable?
You can also do ‘show VisualizeLumen’ to see what Lumen sees to help understand.
Hi , what does your Lumen Surface Cache viewmode look like? I’m guessing there are large areas that are not covered, such that Lumen won’t be able to bounce lighting off of those surfaces.
Also make sure you have Lumen using Hardware Ray Tracing, as such clean indoor scenes require it for good quality. Software Ray Tracing cannot handle thin walls or small window openings.
Here’s a sneak peak at some improvements to Lumen GI on foliage that will be coming in 5.0 release
First the before, GKan’s scene from Preview1:
With improvements that will be in 5.0 release:
Thanks GKan and Yaeko for sharing your foliage scenes. Believe it or not we didn’t have any good ones to test with, and as you know we haven’t had foliage in any of the UE5 tech demos, so we didn’t get a chance to work on it yet.
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Just a heads up, it’s really coming down to the wire here, Thursday is the last day we will be able to fix visual issues for 5.0 release.
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Thats a day and night difference, glad we could help to sort this out. Hopefully this makes it into 5.0 given its visual impact and importance, thanks for being so quick and open about it.
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Thanks Arkiras for figuring this out. I also struggled with this, but suspected a different cause. The difference becomes really obvious when comparing to pathtraced ground truth. This would get my vote for the thursday deadline, if feasible. 
Maybe I figured it out! Thanks for the tips:
It seems that it’s because the ceiling is not (somehow) being considered by Lumen, when I enable r.Lumen.Visualize.CardPlacement 1 I can see only the ceiling doesn’t appear, but the walls do appear. The house is a full static mesh merged with different materials (I saw that because of that, this could not be compatible by Lumen)
View of outside with CardsPlacement enabled:
View of inside with CardsPlacement enabled:
View of outside with Lumen Visualization mode (i’m not sure what those colors mean):
View of insidewith Lumen Visualization mode (i’m not sure what those colors mean):
Although: Even with that all, in editor it works perfectly (the Spotlight works even when not looking at the illumination), and in-game it doesn’t work like I showed in my videos.
Hi
I have already sent you a private message
But now I also sent it via email
Thank you
Unfortunately I’m not seeing visible changes with this command. When I move around camera, this grain effect feels like a post process/temporal/sharpening effect that settles on after short time on camera stop (<0.5s or so?). Not sure if it helps in any way.
Hello! Very impressed by preview so far and happy to hear more is to come in 5.0.
I just have one question about something; In EA I could use Virtual Shadows and let spotlights use distance field shadows as an option, useful for dense indoor areas with many lights for performance reasons. I only really want the directional light to use Virtual Shadows. But now in Preview, spotlights with DF shadows get no shadows at all it seems. Could this be a bug perhaps? Looks like DF shadows still work on directional lights.
/edit: Now that I think about it this is only happening in cooked builds
Thanks for sending me your scene. I investigated what’s happening. This is a really extreme lighting setup, with a very bright skylight set to 50 on intensity, and it gets blocked very abruptly in a line. Even the path tracer has a line:
But it gets way worse due to Lumen’s Radiance Cache. I’m afraid we don’t have a solution to this for 5.0 release. Here are some workarounds you can try though:
- Shift the entire level up or down until the dark line disappears. This changes where the Radiance Cache probes are relative to the geometry. Ugly, I know.
- Raise r.Lumen.ScreenProbeGather.MaxRayIntensity to 100, this fixes the clamping of energy that Lumen is doing
- Disable Lumen’s Radiance Cache with r.Lumen.ScreenProbeGather.RadianceCache 0
After shifting the level, I can get decent results even with Radiance Cache on:
Also, this level has content that Lumen cannot support. Check the Lumen Overview visualization, all of the pink means uncovered surfaces that Lumen can’t bounce lighting off of.
This happens because the level was not built modularly.
From the doc:
Only meshes with simple interiors can be supported — walls, floors, and ceilings should be in separate meshes. Importing large, single meshes are not expected to work with Lumen.
It sucks that Lumen has this content limitation, but it’s what allows us to make it possible in realtime. Fixing that will solve some of the missing bounces, and some of the leaking.
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Would it be possible to pack some demo files or pictures into the docs, so users can see, just HOW simple a mesh has to be, to be still supported? F.E. while walls, floors and ceiling should be separated, can the walls as separate mesh have several corners, or should basically every wall piece a flat segment, and every corner be constructed from several separate wall segments/meshes?
To use an absolute extreme example, should the superstructure of a Super Star Destroyer (Star Wars) be made from just quad meshes? ^.^ That would result in a ton of quads, or could Lumen handle, if just the “main buildings” are separated meshes, that have their clustered surface.
Example picture:
Yes, it will be in the docs when they get updated for 5.0, which will be right before release.
Essentially you can have as complex of an interior as long as it doesn’t show up pink in Lumen Surface Cache viewmode. And even then, if it’s a small area then it’s no big deal. The pink areas just mean that Lumen will never bounce any light from there (and it will be black in reflections).
Something like this works:
But a complex mesh like this has pink areas, even after cranking up Max Lumen Mesh Cards (new setting on the mesh)
In the Star Destroyer, getting perfect Surface Cache coverage isn’t going to matter much, since you’re outside of it (you don’t rely on the GI bounce from it much), and Screen Traces are likely handling most of the GI anyway with such small scale features.
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