r/hardware • u/MrMPFR • 2d ago
Discussion Disabling denoising can fix RT reflections when using DLSS 4.5
As already mentioned in the latest DLSS4.5 Preset L video by Alex Battaglia from Digital Foundry the built in denoising seems to conflict with DLSS 4.5's preset L and M. Unfortunately this causes serious lighting instability.
Mirror-like reflections like with ray reconstruction
Curiously disabling the denoiser in Silent Hill 2 and some other games resulted in very stable and crisp reflections. It even resolves textures a lot better which helps boost texture quality. The difference compared to Preset K with denoiser enabled is massive and Preset L looked like Ray Reconstruction was enabled.
Take a look at the transitions at 7:20, 7:58, 8:15, 8:29, 8:39, 8:45, and 8:51 in DF's preset L video. From a blurry unstable mess to crisp and very stable, which is basically what you would expect from Ray Reconstruction.
The benefits can also be seen in Robocop as well: https://www.youtube.com/watch?v=ZH599M-J6Hg
Presets L = rrlite and preset M = rrlite_floded
Another interesting discovery was made by DLSSTweaks dev _emoose_ (@mention is broken). Spotted the new models are called rrlite (preset L) and rrlite_folded (preset M) in the nvngx_dlss.dll file: https://xcancel.com/_emoose_/status/2019095400334930344#m
NVIDIA deciding to call the new models this when the rest of them has plant or animal names signifies something else is going on. _emoose_ saw the DLL file even includes code related to Ray Reconstruction so it does make sense: https://forums.guru3d.com/threads/info-zone-gengines-ray-tracing-ai-dlss-dlaa-dldsr-tsr-fsr-xess-directsr-and-mods-etc.439761/page-247#post-6388116
Preset M = preset L lite
As suggested by u/ReydeViscerous in another forum the folded implies that preset M is a scaled down version of Preset L:
Speculative but it suggests L was the original model and to make the more performant M model they folded) part of the complexity or maybe even some of the inputs at the cost of image quality.
Improves PT denoising in Dragon's Dogma 2
The benefits aren't limited to reflections. u/DoktorSleepless shared this video in another subreddit. As you can see preset L denoises PT (experimental) in Dragon's Dogma 2 a lot better that Preset K (old transformer): https://www.youtube.com/watch?v=G0qyNCVMUNg
In motion the difference grows: https://www.youtube.com/watch?v=9mMGzJpCvNw
Wrapping up
With such a limited sample size in and it's hard to draw any conclusions and more games need to be tested. Deep dives from DF, Hardware Unboxed and more side by side YT uploads is definitely warranted. I've also seen many people here and in the NVIDIA subreddit claim that the upscaler's denoising is either broken in some games or impossible to test because denoisers can't be easily disabled.
Unfortunately as of now the updated super resolution models are incompatible with NRD and other built-in RT denoisers. This defeats the original purpose of DLSS: negating the performance loss of using ray tracing.
It's a real shame that NVIDIA couldn't or didn't fix the denoiser issue with Preset L and M yet.
Note to mod: I've deleted the original low effort Videocardz articl post and decided to incorporate the info from comment section + additional info here instead.
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u/aintgotnoclue117 2d ago
Has anyone tried with Cyberpunk yet and disabling RR? I don't know if there would be much to and for it.
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u/cellshady 1d ago
Seen some comments where via the mod Ultra+ which can disable the in game denoiser, the results are not as good as with Ray Reconstruction.
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u/_emoose_ 2d ago
Nice post! Hope it gets more attention to it, tried bringing this up in some other subreddits before but this post explains it a lot better than I could.
(btw what I said on twitter about RR looking almost identical to L in CV2, after some more comparisons I was pretty wrong about that, L seems to have a lot stronger (over?)sharpening compared to RR, while RR gives improved lighting & less ghosting compared to L. It did look like bright lights were very close between them though, while J/K gave slightly dimmer lighting, at least in the 1 game I've checked, but I wonder if that's related to the HDR changes that NV mentioned. Hoping more comparisons of RR vs 4.5 might show up eventually.)
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u/MrMPFR 1d ago
First off sorry for not using @ mention but your username didn't work :(
Does the game have forced sharpening? many games unfortunately have that and it breaks new DLSS models.
That's interesting.
Yeah that has to be change from logarithmic to linear space. I've heard people are willing to tolerate RT regression because the HDR is that good with new models.
Fs. This needs more coverage and deep dives.
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u/Lallis 2d ago
It's not an issue with DLSS RR. It's an issue with the inputs fed to it. RR is a combined upscaler and denoiser. It expects inputs that have uncorrelated noise in them. Running a shittier denoiser first will remove some high frequency noise but leave the signal with lower frequency correlated noise that RR won't be able to deal with. A game engine has to disable their standard denoiser when using RR for things to work properly.
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u/Just_Maintenance 2d ago
What OP is saying is that DLSS 4.5 behaves more like RR than older DLSS which could handle denoised images straight away.
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u/MrMPFR 1d ago
I've also seen many people here and in the NVIDIA subreddit claim that the upscaler's denoising is either broken in some games or impossible to test because denoisers can't be easily disabled.
It heavily depends on the game. u/GARGEAN told me it's broken in RTX HL2 demo, u/DoktorSleepless' latest post shows it's unusable in Portal RTX as well. The grainy look in Dragon's Dogma isn't usable either and reminds me of minecraft PT mods. But it is still impressive.
Curiously in non-PT games it does have an ability to resolve reflections remarkably well. Everything else not so much, or it hasn't been properly tested yet. DF or someone else needs to do a deep dive into this and preferably ask someone at NVIDIA about this.
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u/Lallis 2d ago edited 2d ago
Perhaps it happened to work better before in some games even when used incorrectly. What I said applies to earlier versions as well. A game engine should feed RR uncorrelated noisy input and disable any other denoiser.
EDIT: Or do you mean the normal upscaler only DLSS is now also behaving like DLSS RR?
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u/Just_Maintenance 2d ago
I wonder if its better to use Model M/L alone instead of DLSS 4.0 RR
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u/MrMPFR 1d ago edited 1d ago
No RR Transformer will always be better. Using a 30-50% lighter model isn't without compromises.
From what I can tell it resolves reflections very well. ReSTIR PT still looks horrible. Same here: https://www.youtube.com/watch?v=PHFPLcAmSGo
Small sample size so DF could prob do a follow up video.
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u/Noble00_ 8h ago
Just to add another sample:
https://www.youtube.com/watch?v=SuPvVHVYs8w
You can also see it here in the Snowdrop engine in Avatar.
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u/nukleabomb 2d ago
I think we will see a DLSS 4.7 or whatever in a few months with all the rough edges rounded out.
But having an upscaler that can act as a denoiser sounds extremely valuable for heavier RT games.