Why does OptiX Denoising work in Viewport but not Render when rending a specific (large) scene?

Question

I cannot get OptiX Denoising to work on the final render for my complex scene. However, if I create a new scene and render the default cube (using low samples as a check), OptiX denoising works for both render and viewport. With my large scene, the OptiX Denoising pass does not occur after rendering is done. All settings in the "Render Properties" and "Output Properties" panels are identical between files.

Could it have something to do with the size of my scene? My GPU memory is almost entirely filled when rendering my full scene, though hiding some of my layers (even leaving only the backwalls) doesn't help. Does anyone have any ideas?

Details:

Blender ver: 2.93.0
GPU: RTX 3070
CPU: AMD Ryzen 7 5800X
Cycles Render
Devices: CUDA - GPU+CPU

Answer 1

you can try to checklist denoising under this section

*check image below (blender 3.2)

Answer 2

I think the issue experienced by the user asking the question may be that they expect the denoising to occur while the individual samples are rendered. I experienced the same issue.

I think it may function differently than viewport denoise which iteratively densoises but I'm not exactly sure.

I was able to get things working by following the instructions on the following video https://www.youtube.com/watch?v=5A2ahhFT7Fw

"View layer properties -> Passes -> Data -> Denoising Data "

Followed by configuring the "Denoise" element on the compositor tab. I'm not sure if this is strictly necessary or not. Perhaps the denoise functions without the compositor if you just wait until it finishes rendering all the samples.

Or perhaps there is a way to get the iterative denoise funtionality of the viewports working in the render window, but I wasn't able too, so I'm just posting the solution I used here.