AI denoiser question

[Omegauser9]

So I'm a bit confused, someone please explain exactly how the Denoiser works please?

From my understanding, which I'm sure is wrong:

The Ai denoiser lets you lower the Samples you want for a scene (I think default is around 16k?) allowing you to utilize a faster render time, but in lieu of a higher noise ratio the Denoiser comes in and cleans that all up.

If I'm right in that, how does the AI light contribute?

[abstrax]

So I'm a bit confused, someone please explain exactly how the Denoiser works please?

From my understanding, which I'm sure is wrong:

The Ai denoiser lets you lower the Samples you want for a scene (I think default is around 16k?) allowing you to utilize a faster render time, but in lieu of a higher noise ratio the Denoiser comes in and cleans that all up.

If I'm right in that, how does the AI light contribute?

The AI denoiser removes all high-frequency noise, but tries to conserve details of geometry and textures. If your image is too noisy, you will start seeing artifacts, but it works great if your noise level is not too high anymore and you really don't want to wait another hour to completely get rid of that noise.

AI light contributes only indirectly by improving the direct light sampling thus reducing noise quicker in certain circumstances. AI light and AI denoiser are two different things.

[frankmci]

So I'm a bit confused, someone please explain exactly how the Denoiser works please?

From my understanding, which I'm sure is wrong:

The Ai denoiser lets you lower the Samples you want for a scene (I think default is around 16k?) allowing you to utilize a faster render time, but in lieu of a higher noise ratio the Denoiser comes in and cleans that all up.

If I'm right in that, how does the AI light contribute?

As I understand it, the AI Light is specifically for optimizing scenes which have lots of small light sources, like a big interior with lots of ceiling point-spot light fixtures. If you have something like a basic daytime exterior, or a standard three point studio lighting rig, it's not really going to do much for you.

[itsallgoode9]

glad this topic was brought up, the aiDenoiser and aiLight weren't super clear to me.

out of curiosity, is there any reason to not have aiDenoiser enabled? I'm sure there must be, otherwise it'd just be always on

and yeah, could you clarify what types of situations aiLight helps improve and any downfalls of just having that always on, as well?

[frankmci]

My understanding is that the AI Light function will more intelligently sample a light's contribution to each surface's illumination based on distance, and relative to the overall scene lighting, so that each light source is sampled more often closer the it is the the surface in question, reducing noise. This is instead of assuming every light in the scene should either be treaded the same, or instead of (/in addition to?) relying upon the Sampling Rate attribute of each light. My understand of this is questionable.

Why not use it all the time? I can imagine situations where you want to have specific, manual control over each light strictly using the Sampling Rate where this might get in the way. Also, from what I gather, AI Light can slow down the interactivity of your real-time view, even thought it speeds up the overall render time for the image.

There's a checkbox for "AI Light Update" which I think is supposed to disable the re-calculation of the AI Light weighting, but continues to use whatever values were last stored if you have previously rendered the scene. If you're not repositioning or changing the settings on your lights, you can keep that off and speed up interactivity while keeping the noise reduction benefits.

As for AI Denoiser, it does use up some VRAM, so that might be an issue. It also adds a short delay a the end of your frame render, or potentially multiple times if you are using a denoise interval on longer renders. If you've got the luxury of lots of GPUs, you can dedicate one to just denoising without any loss of VRAM on the other cards.

[tim_grove]

glad this topic was brought up, the aiDenoiser and aiLight weren't super clear to me.

out of curiosity, is there any reason to not have aiDenoiser enabled? I'm sure there must be, otherwise it'd just be always on

and yeah, could you clarify what types of situations aiLight helps improve and any downfalls of just having that always on, as well?

My experience with the AI Denoiser suggests that there will be lots of circumstances where it will soften details of complex textures/bumps in specific lighting scenarios. It's important to still test your scene, optimise your settings and compare some frames to ensure the results are suitable for your requirement.

My best practice has been separating the beauty and denoised beauty, then compositing the denoised beauty over the top of the original beauty with a little opacity, the amount differs from scene to scene, sometime 80%, sometimes 40%. There is an option for this in the denoiser called mix I think but having two passes gives you that extra control.

I've made 4 images here for you to take a look at, this scene could actually be optimised much better, but this is a good example of a successful workflow with the denoiser. I'd suggest you lay them over each other in photoshop and turn each layer on and off to compare the difference. I might add, that this was also an animation and once converted to H264 and absorbed by most platforms it loses 90% of the detail anyway.

[Micha3D]

out of curiosity, is there any reason to not have aiDenoiser enabled? I'm sure there must be, otherwise it'd just be always on

Some times the denoiser cause longer render times. Best test your times before start a lot of renders. The issue will be optimized in the future.

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