Noise

[WimOos]

I need some help please.
Trying to get this sequence rendered in Vantage, but the noise is terrible.
Herewith a link to a portion of the video : https://vimeo.com/738203958
(trying to upload video but I get an invalid link notice)

The video is rendered with 400 samples and nvidia denoiser.

I have tried increasing samples to 2000 but it has the same problems.
Rendering with the denoiser off and 2500 samples, gives me this attached blotched render.

Any suggestions please?

[vladimir.nedev]

How are you lighting this interior space. Where is the light coming from ?

Greetings,
Vladimir Nedev

[WimOos]

Mostly a vray sun with vraysky. It is a conversion of a warehouse, and they wanted to show that you will get enough daylight in from the opened sides and some roof lights. There are some downlights in some places, but most of the ligthing is from the skylight

[npg]

Are you using auto-exposure? Are you using non-zero noise threshold? Try turning either or both off.

[vladimir.nedev]

Do you have the light cache enabled ?
If you are using multiple GPUs, the light cache is automatically disabled.

Greetings,
Vladimir Nedev

[WimOos]

I used Auto-exposure, with noise threshold set to 0.001. How do I turn the noise threshold off - just by using 0?
I will try without auto-exposure and get back with the result.
Light cache was enabled.

thank you!

[WimOos]

I get much better results with Auto-exposure off. Will render a section like that and get back with results

[npg]

Yup. Most likely the scene was very dark, which AE compensated for, but currently the noise level calculation is not aware of this exposure correction and will see the dark areas as sufficiently clear of noise and will disable further sampling of these pixels. It's on our TODO list to fix this. You could still render with AE, just make sure the frame is not extremely under-exposed (while AE is off) to avoid this issue. Alternatively instead of adjusting camera exposure or lighting, disable the noise threshold (set to 0) and just fully render the 100-200-400-whatever samples the scene needs.

[WimOos]

Perfect! thank you kindly for your help.
Your explanation makes a lot of sense. I turned AE off.

A quick question regarding noise threshold : when is it preferable to disable it?

[npg]

In general it's fine to always use a noise threshold (NT) - this is the default behavior after all. This AE bug is the exception and it should be fixed in a future patch. To avoid the bug, check your cameras with AE disabled before final rendering. If they are very dark (like hard to tell what's there) you'll have to either adjust the camera exposure parameters or disable the NT. Disabling the threshold may increase render times. You can still render final with AE and NT if you don't want to tinker too much with the cameras (and don't want it to be slower either), but the cameras should be at least somewhat near a decent exposure setting to avoid leftover noise.

[WimOos]

thank you. makes sense.