We did change Lumen screen traces to no longer pick up translucency in 5.3, and unfortunately this didn’t make it into the Release Notes. Translucency in screen traces is always going to be broken in one way or another, since screen traces are intersecting the depth buffer, which only opaque materials write to. There were some catastrophic cases where foreground transparency would light up the background. Now translucency doesn’t show up in reflections, instead of showing up in the wrong spot.
To confirm, does this mean there is a technical solution, at all, or is this impossible to solve?
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‘hardware ray tracing’ is not deprecated in UE5, but rather the Standalone Ray Traced Reflections method. Open your Project Settings, search ‘Reflection Method’ and read the descriptions. Standalone Ray Traced Reflections are replaced with Lumen Reflections with ‘Use Hardware Ray Tracing when available’ enabled.
Have you guys looked into what Nvidia is doing with Ray Reconstruction in DLSS3.5? Seems to do a great job of reducing noise and I heard them say they generate specular motion vectors along with combining denoising and upscaling at the same time.
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Are there any plans to implement backscattering support for SSS materials in the surface cache? Noticed that this doesn’t work for Legacy or Substrate materials and screen traces are skipped for everything but subsurface profile.
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Wow, that works amazingly well. Honestly from a development perspective that’s more than acceptable, lighting and scene geo can be tweaked but the lack of a solution to noise was quite bad. This changes things.
Pardon me asking, but if glossy reflection denoising isn’t high on the priority stack, what’s on the (preliminary) docket for the lumen team for 5.4?
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If you need a shipping example of how jarring it can be, go down an elevator in Elden Ring with a lantern on your belt and look at the walls.
Elden Ring isn’t UE5?
Hi Daniel,
Unfortunately, no. This is what I see with double layered, two sided windows (so 4 faces together) with thin translucent shader. The sun is not casting shadows through the glasses, instead it seems like it is handling it as opaque.
So far, it was working without hardware raytracing, but now even in software raytracing, it is not working properly in 5.3. So far it was working with software raytracing, and for hardware raytracing, we just used the above console command to solve this issue.
Lumen reflections are now compatible with baked lighting (thank you), but number of bounces doesn’t work unless you enable Lumen GI.
So, number of bounces of Lumen reflections are not compatible with baked lighting.
It’s working fine for me too. Maybe it’s your material. Can you show it? Have you tried with a very basic translucent material, to compare?
No it’s not but you can see the effect in motion. It’s similar if not driven by the same limitations of a ray + accumulated math.
If I enable ray traced shadows for the directional light, it stops working.
Oh, I think that’s a different scenario. But you can uncheck Cast ray traced shadows inside the material params.
Unfortunately, that’s not a solution for us because we use the pathtracer too. So far, it was working with the above lumen command perfectly…
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Hello,
Ray Reconstruction demo showcase here with lumen : https://www.youtube.com/watch?v=GOhK4V9lGtU
Pretty impressive 
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Weeeelllllll… Cyberpunk sent out it´s update for downloading, and while it seems to be activated on the 26. (no clue, have not yet looked for Phantom Liberty stuff), the options for DLSS 3.5 are already there and so is Ray Reconstruction.
Which… is greyed out with normal settings on an RTX 2070 o.O
Did i manage to get it activated? Yes. Was i happy about the result? Nope 
I kinda feel scammed 
While they spoke the truth, you CAN activate Ray Reconstruction on any RTX card, and just as suspected, it is indeed independend from Frame Generation. What they didn´t mention in the trailer is, that it is tied to PATH tracing, not just the ordinary Ray tracing.
So in order to get Ray Reconstruction, i need to activate Path tracing, which is possible, but comes with a big fat warning, that its so performance hungry, that it should only be activated on an 3090 or higher.
THEN i was indeed able to use Ray Reconstruction, with a loss of 25-30 FPS…
Thanks a lot, i guess 
Just getting 29 FPS thanks to Path Tracing.
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Thanks for the reply!
I understand that lumen is mainly optimized for game environments. However it would be nice to get a quality switch that aims for high quality production where realtime performance just isn’t important.
At least in the movie render queue I think its a shame that lumen quality doesnt really scale with the amount of samples you give it. Especially the noise and flickering issues.
We are currently working on a big office space with a ton of different materials and extremely difficult lighting scenarios and we are constantly tweaking console commands while also being in contact with udn support. But one thing will often break another and its hard for a small studio thats mostly artists to figure out something complex like lumen.
It would also really help everyone working in archviz or other similar areas to get back (usable) raytraced shadows since Virtual Shadow maps are just not reaching the same level of quality and do not match the pathtracer at all. The only thing stopping us from using raytraced shadows is the fact that there is no SSS.
Bonus question: where do see lumen in comparison to realtime pathtracing like in cyberpunk especially with the fantastic results with the DLSS 3.5 integration? And can we use ray reconstruction with the build in pathtracer?
Thanks!
Is there a recommended workaround for this since it really makes translucent objects look fake?
You need to use NvRTX Caustics branch :https://github.com/NvRTX/UnrealEngine/tree/NvRTX_Caustics-5.2
It has the so far best translucency solution, and here is the just released live stream:Level Up with NVIDIA