Denoiser - late to the game!

[tricky]

New things scare me. When the VRay Denoiser first launched, it sounded great. Everybody raved. I had a quick go with it. My image was certainly smoothed out, but lots of the fine texture detail went with it. Deadlines and workload meant I didn't have too much time to test, but now I have come back to it to see if things can be improved.

All I seem to find is that all my fine texture detail is lost, regardless of the settings I use. Are people actually using it in production? For example, I have a large, slightly polished concrete floor. Even with the 'mild' preset, the result is overly smooth, like the lens is smeared with vaseline.

Does anybody have any good tips that are tried and tested, or is it only a useful option in certain situations - high resolution work for example? (the scene I am working with is to be rendered at 1920x1080 only).

[Alex_M]

Yes, denoising certainly can smear details but if you use it intelligently it can be really useful and avoid this from happening. I've already used it in a number of jobs with great results. Here's what I do.

If I know the scene will have important textures with fine detail, I render with low noise threshold (0.01-0.03) and use the Mild preset. But If the image to be rendered doesn't have important fine detail textures or no fine detail textures at all, I render with high noise threshold (0.03-0.05) and use the Default preset.

To chose which way I go (low NT/Mild denoise vs medium NT/Default denoise), I do small region test renders in final render resolution around the objects I'm concerned about being smeared.

[tricky]

I see - so the results of the denoiser are influenced by the quality of your basic render quite a bit then - I'll keep testing. Thanks.

[Alex_M]

Yes, I've found that it is influenced by Noise threshold. I remember that when I tried to denoise really noisy images, the denoiser began blurring the details in the textures. If you have the time you can do some tests and you'll get the hang of it.

[andybot_cg]

I've just ended up masking off areas like that in post and using the original render for those areas. Good tip about noise threshold and denoiser settings. I hadn't seen that much difference between the denoiser settings. I'll have to try adjusting the noise threshold.

[dlparisi]

I've just ended up masking off areas like that in post and using the original render for those areas. Good tip about noise threshold and denoiser settings. I hadn't seen that much difference between the denoiser settings. I'll have to try adjusting the noise threshold.

Depending on the scene, I've also done a 50% blend of the denoised image over the regular image. It keeps the detail but tones down the noise a little so it's not as "contrasty". I typically just save all elements anyways so I have the RGB and the denoised versions so it takes no time to layer them over each other.

[Alex_M]

dlparisi Good tips!

[AlexP]

Use it on every image, but its obviously better at higher res

[thanulee]

No good results with denoising so far. Makes perfect sense to use low thresh when detail, but still cannot use it, it smudges. Lots of tests, no good results and especially in anim it causes flicker to be more pronounced.

[gadzooks]

Depending on the scene, I've also done a 50% blend of the denoised image over the regular image. It keeps the detail but tones down the noise a little so it's not as "contrasty". I typically just save all elements anyways so I have the RGB and the denoised versions so it takes no time to layer them over each other.

Exactly how I do it!