Performance is definitely one of the big questions for me- Surface Cache GI with hit lighting reflections already got incredibly close to PT reference in my testing, so I’m curious in terms of what content could really benefit from this system in a large way. Besides emissives, I do remember testing a herringbone-style wall mesh that significantly broke lumen GI, with massive amounts of lost energy compared to PT.
Maybe it will drastically reduce noise, patches and weird AO, beside more general accuracy.
okay. i get it. raytraced direct makes a clean sun shadow in the highrise “windows”. reflections. the skylight was already good but it was noisy. also… in the prior test “renders” i intentionally shot the spotlight into the mirror surface to portrait lumen gi reflecting onto the ground. i reckon in raytraced mode this is too direct (without multiple samples) and will not yield the spread the surface cache has.
and the emissive cubes in my test map look very stable, now. hmmhmm
nice. 
screen percentage is 100% btw. it’s not full blown maps but technically okay in screenspace. and runs cool.
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How well do the area shadows resolve in reflections? I’d struggle to believe that would make a large visual difference in most scenes, but I’m curious about the perf cost.
well… they don’t resolve. this would be rather expensive, i think. the directional light according to staff is a brute force xtra pass that mosdef is not represented in the reflection bvh. i dunno how the rect light is rendered. both do not smooth tho.
jsyk… the directional light is blown up to 90 source angle for the first hit and 90 source soft angle for the smooth reflection math. the rect light is visible. that’s what you’d get.
and the before…
(i wish the light bounce from the spot mirror would still be there in the main pass. it is reflected light but lumen handled that bounce pretty da*n well.)
nvm. it only shows up in lightingmode 2. btw… you should point your camera at a mirror and run thru the console variables. you’ll figure it out. the controls are nice. scene dependant tweaks can be made.
and a lil roast mode with possible puddles. i’m aware the ps5 gotta do that in 1440p at stable 30+ fps. or even more on the ps5 pro. i can see the development. yo…
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a minor inconveniance i noticed in this test map a couple of times. the “overcast” direct light, at certain backwards angles, throws a bunch of noise onto flat surfaces. not sure if this is mathematical or a content issue. cheap boxes are no good, i know.
also happens on the box i put infront of the rect light.
I was browsing through some cvars when I discovered something interesting. Looks like we might get RESTIR Lumen at some point. Trying to activate it will just black out the scene unfortunately.
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Hey guys! Great work on 5.4. Im trying to build stand-alone on the quest 3 and even with global clip plane enabled I can’t seem to adjust my setting to get the planar reflections to show up in both eyes. I’ve toggled the stereo view and multi view modes for multiple builds and tried adjusting the false eye offset, but it always seems to have a very similar result. Any suggested setting to get this working on a quest 3?
Since planar reflections aren’t a lumen technology, I’m not quite sure this is the right place for your question. That said, I don’t believe planar reflections are supported by VR? At least not in the documentation I’ve seen.
Hey, this tutorial will be of great help to improve satin materials reflections
I think this is the one of the worst lumen Tutorials I’ve seen so far. Extremely biasing the reflection ray intensities and then messing up the desired material roughness values to compensate for it is one of the worst ways to go about it.
You are essentially completely changing what the original material is supposed to represent just in order to remove artifacts caused by combination of the technological limitations and incorrect sampling settings.
In real world, if you do archviz and client tells you “the table is not supposed to be shiny polished wood, it’s supposed to be matt finish”, then you are screwed because as soon as you increase roughness again, you will lose reflections almost completely (due to the excessive reflection ray clamping), in which case client will again say “the table is not supposed to be completely rough finish, just a matt polish, but not glossy”.
The fact you dare to advertise paid courses called “elite renders academy” at the end of showcasing such poor, beginner understanding of Unreal’s renderer, it’s a cherry of cringe on top 
My response may sound unnecessarily harsh, but it really frustrates me when people with merely the most basic understanding of things immediately start their own paid courses and academies these days, because it feels like its scamming other beginners out of money, for low quality information, and beginners especially are usually running short on money. 
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Hey there, thanks for your feedback, yes we surely know this is not the most physically correct. However when using Lumen for arcvhiz its still all about workarounds to make it look better as it´s reflection quality is still to poor when comparing it to offline renderers where none of this hassle is needed.
Hopefully in the future lumen visual quality keeps going up as it has been doing in the last updates so these type of tricks are not needed , hope we can have real time rendering and nice and accurate reflections both together, but for now it´s a great help to remove this noise that we and many others needed to ignore everyday when working with satin materials.
Our paid training will be focused on understanding the software but also on how to tweak it enough (which currently is the hard work when working with lumen) to make it get great results to sell your interior/furniture design on your clients presentations, which is the main goal of these type of renderings.
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I normally do not join in on these conversations, especially where it is not particularly the best place. But @Rawalanche is absolutely right. If you mean it as a display model it’s one thing, but for archviz where it’s more important to be able to change things quickly and reiterate. It’s more misleading than anything. I do not recommend publishing your own paid courses without proper experience. Hence why I do not run paid courses, I’m inexperienced.
But for why I came here, how can you get rid of noise on foliage with Lumen?
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Small foliage like grass behaves almost like a random noise generator, as Lumen doesn’t simulate transmission through it.
In order to fix it, remove small foliage like grass from Lumen scene (disable visible in ray tracing or affects distance field lighting). If you use screen space traces then set shading model to thin foliage or subsurface, so that screen space traces skip it. When it’s set correctly it should be affected by r.Lumen.ScreenProbeGather.ScreenTraces.HZBTraversal.SkipFoliageHits and r.Lumen.ScreenProbeGather.ShortRangeAO.ScreenSpace.FoliageOcclusionStrength.
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Thanks so much for your assistance! I really appreciate it!
Would it be possible for Skeletal Meshes to sample the translucent lighting volume for indirect lighting in reflections? Seems like that could work better than just having them be black. At least for exteriors anyway… I imagine lack of resolution could be a problem in interiors.
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Yes, it would be possible through a bit more involved as reflections may hit something off-screen, which then would need to generate additional probes.
The plan is to try to exploit the fact that we need translucency probes only in frustum to improve their quality, and then change how surface cache works so that it can work on anything without a static mesh build step. We’ll see how it turns out in practice.
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UE5.4.1 Under the influence of Lumen, the dark parts of vegetation leaves are almost pure black.The performance of Lumen affecting vegetation seems to be regressed.
A big Lumen commit landed today.
https://github.com/EpicGames/UnrealEngine/commit/442a01461ac799ef42d6d88eb27f75395aa46560
Initial Lumen stochastic scene lighting.
This version adds initial support for stochatic Lumen scene lighting. This can be enabled with r.LumenScene.DirectLighting.Stochastic 1. By default temporal filtering is enabled. This can be disabled with r.LumenScene.DirectLighting.Stochastic.Temporal 0.
This version has a few issues which will be addressed as follow up:
* Multiple sample per texel result in RT occlusion test being incorrect some
* Temporal history is mark as valid even for cards being just added. This causes a flicker on their first refresh frame.
#rb Krzysztof.Narkowicz
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nice. the code reads like soft shadows in my city test reflections. it’s hot outside but i’ll let the code simmer. (after i redownloaded the whole repo again - github corruption and ms build conflicts are not poggers) yep
nope. it’s not building today. fresh meat. but i dunno howto debug build syntax. all good. i’ll be back. 
