Thanks Lele for all these tests and very interesting analysis. This also explains why my results with the denoiser were always awful and I couldn’t understand why people even used it in the first place. I’ll refrain from using this trick. I’m glad I asked, and now I even understand why :).
I’m glad you took the analysis the right way! 
Ouch, i’m so sorry to hear this.
Keep a decently high Max AA (so it doesn’t clip/red in the samplerate RE), and only play with the noise threshold to drive render speed.
Then the denoiser will work its magic, and you should be able to get away with much higher noise thresholds than previously, for a higher final quality.
This thread was super useful and started some slightly left-field discussion on sampling with the devs, so thanks for bringing it up again!
Did I miss this?
My results with the denoisers are always garbage, even with default settings, or min 1 Max 100 (Universal) settings, etc. They destroy way too much detail. I find them useless in production for VFX work.
But I guess somebody uses them?
Highly likely you’ve already used it!
EDIT: Here’s the paper about it.
I shall state i have zero experience of denoising in VFX productions (i’d have been hanged.), but have you tried the v-ray denoiser with multi-frame denoising?
If you have, have you tried it recently, since the introduction of the albedo RE?
Very curious to hear your thoughs!
Yes, did the standalone denoiser, hoping it would be a lot better, and was still disappointed. It always seemed to throw away too much detail. With a wet/dry mix it may have looked a tiny bit better than not-denoised, but having to deal with all the data of the extra denoisers passes, and the extra steps of denoising (I know I could script that in Deadline) it just didn’t seem worth it.
As you know we are typically ADDING noise to VFX elements anyway (render them a little cleaner than needed and a little sharper than needed and then adding noise and softening a touch).
Tries standalone, and tried all the various one-shot denoisers too.I think the Intel had the most promise, but still threw too much away. Post denoising with the likes of Topaz AI stuff seemed promissing, though they are seeming to head towards more of the “app” feel in their latest versions, which I can’t stand. (simplified big buttons, terrible UIs with no discoverability-- Just like modern Apple stuff-- breaking every rule that was in the original Apple Human Interface Guidelines that made software so usable. Change for change’s sake is ignorant.)
When was the Albedo RE added in to the equation? I think the last time I tried it was around VRay 6.0 (no hotfix).
Thanks for the detailed explanation. This was really useful !
Mh, can’t quite recall.
V6 is a sure bet, and the element should show up as “albedo” in the RE list while rendering.
So the Albedo RE only shows if you have a Denoiser RE?
Yes, with the NVidia and Intel ones.
It’s a compound one, made of a few shading aspects.
It’s unlikely it’d be of any use in compositing, as that info is already contained, and properly separated, in the various filter render elements (i.e. diffuseFilter, reflectionFilter and so on.).
Would you want it added to the REs list?
Well unless I’m wrong but an albedo element is sometimes quite handy to check if some values in the scene are too bright or dark. Corona has a CShading_Albedo element, and anything in red has a too bright value (or last time I used it, it was like this), which is quite handy. But that’s another thing of course.
https://support.chaos.com/hc/en-us/articles/4528323859601: bottom of the page.
I see.
Sadly it’s not clear what “too high” is, i assume full 1.0 white?
It’s surely handy, but i’d have the level editable, so one can choose what the max albedo inside a given scene should be and work off that.
This sounds like something better done with a “Zebra Bars” layer in the VFB (or compositing app). Basically a layer showing you anything over a certain value like the old Zebra Bars on video cameras (the 100% level). This could be shown by a bright color, or old school Zebra Bars, or whatever.