Denoiser works only in viewport Iray mode, not in renders

straitjacketsonwomen

Hi everyone,

I've been having some trouble with the denoiser for some reason and I can't figure out why. I'm running Windows 10 on an i7 with 64GB of ram and a GeForce RTX 2080 and I've tried using both 4.11 and 4.12.

While creating and designing a scene, I will periodically switch from 'texture shaded' to 'Nvidia Iray' mode in the viewport draw settings while testing lighting and shadows and to get an overall idea of what the render will look like when complete. When I turn the denoiser on and select Nvidia Iray mode (regular default filter settings other than selecting the two denoiser apply buttons) everything works fine and the denoiser activates in 8 iterations. Within mere seconds, my image looks great and nearly complete with absolutely no noise. However, anytime I actually go to render an image, the denoiser doesn't do anything, at all. It never seems to engage and the image looks noisy and grainy. This is even after 8-16 hours of rendering while I am at work. If I stop the render, the denoiser stops working completely, even in the viewport when I go to select 'Iray'. Almost as if initiating the render turns of the denoiser completely. If I close Daz and then bring the scene back up, the denoiser begins working again, but only in the viewport. I have only the RTX 2080 selected for the hardware devices in both interactive and photoreal. I've tried this with dozens of different scenes, get the same results and can't figure out what's going on.

So to summarize, Denoiser works fine in the viewport when Iray mode is selected, but does not work at all when actually rendering an image. Any help would be greatly appreciated.

Thank you in advance.

Paintbox

Hi, there seems to be some kind of bug (at least in my experience) where the denoiser doesn't kick in when you use preview alternately. I am pretty sure that it always have to do with GPU memory. You probably render a lot bigger for the final renders, and this can take a bit more video memory.

It's easy to check if this is the case, just delete a figure, and see if the denoiser kicks in then.

Could be something else, but try this first.

kenshaw011267

It sounds like your renders are dropping to CPU, 8 to 16 hour renders that are still so noisy the denoiser could help. The denoiser doesn't work on renders running only on CPU. If you check the log you'll see that warning if I'm right.

Also the denoiser does take some amount of VRAM so scenes that just barely fit on GPU also will keep the denoiser from firing.

straitjacketsonwomen

Paintbox said:

Hi, there seems to be some kind of bug (at least in my experience) where the denoiser doesn't kick in when you use preview alternately. I am pretty sure that it always have to do with GPU memory. You probably render a lot bigger for the final renders, and this can take a bit more video memory.

It's easy to check if this is the case, just delete a figure, and see if the denoiser kicks in then.

Could be something else, but try this first.

Thanks for the reply, it gave me an idea. So what I did was start a render with the exact same dimensions as the view port, and it worked fine. I increased the size a bit and it still worked. I continually increased the size until it didn't work anymore. So it sounds like it is something with the GPU memory. Any suggestions to compensate? Because I do have a lot of memory that isn't being used during renders. Do you know of a way to utilize that?

kenshaw011267

If you're out of VRAM you're out of VRAM. The things you can do are optimize the maps in the scene or remove items from teh scene until it renders on yoru GPU with enough VRAM left to fire the denoiser.

straitjacketsonwomen

kenshaw011267 said:

It sounds like your renders are dropping to CPU, 8 to 16 hour renders that are still so noisy the denoiser could help. The denoiser doesn't work on renders running only on CPU. If you check the log you'll see that warning if I'm right.

Also the denoiser does take some amount of VRAM so scenes that just barely fit on GPU also will keep the denoiser from firing.

I did a test render and I looked at the log to see what the results were. I've included a screenshot of the results on the portion that I assumed what what you were referring to with the warning. Is this anything that you can make some sense of? Unfortunately, I don't know a ton about how this stuff works and I have really never used the log for anything. Is there some sort of a way to make sure that the CPU doesn't engage during the render? I have a lot of memory that isn't being used when renders are drawing. It seems like a waste of all the memory that is onboard the computer. There really isn't a ton of stuff in the scene, so it surpirses me that the denoiser is this sensitive and quick to stop working.

kenshaw011267

I'd need to see more than that. Above that point is it ever rendering with just the GPU?

Yes you can make sure the render never drops to CPU but any render that would will fail completely instead. Render Settings -> Advanced -> Allow CPU fallback

Paintbox

Looks like you are using around 7.2 Gb , do you have a 8gb card? It might not be enough for the denoiser to do its work. The 2xxx series is a bit more lenient because of the RTX cores, but the 1xxx series needs more memory to do the denoising job.

You can also use Scene Optimizer (search in store) to cut down on texture size for far away objects. That will work. Textures take the most amount of VRAM and you won't know the difference if it its a couple of feet / meters away from camera.