Optix denoising is not working everywhere. #78571

New Issue

Colin Marmond · 2020-07-03T11:35:26+02:00

Colin Marmond commented

2020-07-03 11:35:26 +02:00

System Information
Operating system:
Linux : 5.6.0-0.bpo.2-amd64 #1 SMP Debian 5.6.14-2~bpo10+1 (2020-06-09) x86_64 GNU/Linux
Nvidia : Driver Version: 440.82 CUDA Version: 10.2
CPU :AMD Athlon 2 with 8Gio RAM
GPU: Nvidia Gtx 750 2Gio VRAM

Blender Version
Broken: 2.90 dev master

Short description of error
The Nvidia optix denoising does not work on the entire frame. It just makes a circle denoised; the rest is denoised strangely. This results in a not efficient render.

Exact steps for others to reproduce the error
Open Blender 2.90 master with startup config. In settings, change to device Optix, then in the scene, go into Cycles). Replace the cube by a plane. Add a material to the plane with 0.2 Roughness. Then remove the light and put the camera near the plane. Then, put the samples to 2 for render and view-port. Activate denoising with optix, and start a render preview in the view-port.
bug.blend

**System Information** Operating system: Linux : 5.6.0-0.bpo.2-amd64 #1 SMP Debian 5.6.14-2~bpo10+1 (2020-06-09) x86_64 GNU/Linux Nvidia : Driver Version: 440.82 CUDA Version: 10.2 CPU :AMD Athlon 2 with 8Gio RAM GPU: Nvidia Gtx 750 2Gio VRAM **Blender Version** Broken: 2.90 dev master **Short description of error** The Nvidia optix denoising does not work on the entire frame. It just makes a circle denoised; the rest is denoised strangely. This results in a not efficient render. ![bug.png](https://archive.blender.org/developer/F8661304/bug.png) **Exact steps for others to reproduce the error** Open Blender 2.90 master with startup config. In settings, change to device Optix, then in the scene, go into Cycles). Replace the cube by a plane. Add a material to the plane with 0.2 Roughness. Then remove the light and put the camera near the plane. Then, put the samples to 2 for render and view-port. Activate denoising with optix, and start a render preview in the view-port. [bug.blend](https://archive.blender.org/developer/F8661302/bug.blend)

Colin Marmond commented

2020-07-03 11:35:26 +02:00

Added subscriber: @Kdaf

Gilberto Rodrigues commented

2020-07-04 08:29:43 +02:00

Added subscriber: @Gilberto.R

Gilberto Rodrigues commented

2020-07-04 08:29:43 +02:00

Setting rendering device to Optix is for RTX cards only, Didn't it warn you in the preferences "no compatible gpus found"? yours is GTX, which doesn't fully support it, only the the Optix Denoiser. For using the optix denoiser, go to the preferences you should have your rendering device as CUDA. Ok. Now put cycles as the render engine and set Optix denoiser under the Properties Editor->Denoising->Viewport. turn on the checkbox and change it in the dropdown from open image denoise to Optix Denoise.

Colin Marmond commented

2020-07-04 08:55:05 +02:00

The same problem comes with CUDA activated in the settings (not optix) and the Optix denoising enabled. I always have this weird circle of delimitation between two area, one is denoised and the other one is not denoised. You can see the result (CUDA in the settings with the optix denoising enabled) :

The same problem comes with CUDA activated in the settings (not optix) and the Optix denoising enabled. I always have this weird circle of delimitation between two area, one is denoised and the other one is not denoised. You can see the result (CUDA in the settings with the optix denoising enabled) : ![Screenshot_20200704_085233.png](https://archive.blender.org/developer/F8663158/Screenshot_20200704_085233.png)

Colin Marmond commented

2020-07-04 12:08:00 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

jacopo commented

2020-07-07 11:38:56 +02:00

Added subscriber: @volto

jacopo commented

2020-07-07 11:38:56 +02:00

hi 2060 super user here i rendered the scene on my gpu and it looks like it isn't working but if you look closely the closer the plane goes to the camera the less noise it has; that's because the optix denoising it's trying to do his best with only 2 samples it can't do much

![Annotazione 2020-07-07 113648.png](https://archive.blender.org/developer/F8675160/Annotazione_2020-07-07_113648.png) hi 2060 super user here i rendered the scene on my gpu and it looks like it isn't working but if you look closely the closer the plane goes to the camera the less noise it has; that's because the optix denoising it's trying to do his best with only 2 samples it can't do much

jacopo commented

2020-07-07 11:51:27 +02:00

here i added a lamp to make it look more obvious

here i added a lamp to make it look more obvious ![Annotazione 2020-07-07 115100.png](https://archive.blender.org/developer/F8675178/Annotazione_2020-07-07_115100.png)

Patrick Mours commented

2020-07-08 15:16:13 +02:00

Added subscribers: @LukasStockner, @pmoursnv

Patrick Mours commented

2020-07-08 15:16:13 +02:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Patrick Mours commented

2020-07-08 15:16:13 +02:00

This isn't an issue with the OptiX denoiser, but the denoising passes generated by Cycles (which are passed on to the OptiX denoiser, but are incorrect, so the OptiX denoiser cannot produce correct results):

Noisy	Denoising Albedo	Denoising Normal

The problem occurs when the material uses both low roughness and base color values, which could indicate an issue with how denoising data is handled with specular closures. I'm guessing that since denoising data updates for specular-like closures in `kernel_update_denoising_features` are deferred to the next bounce, but in this case the next bounce likely hits the background, it's never updated. @LukasStockner is more familiar with this code I think, maybe he could chime in?

This isn't an issue with the OptiX denoiser, but the denoising passes generated by Cycles (which are passed on to the OptiX denoiser, but are incorrect, so the OptiX denoiser cannot produce correct results): | Noisy | Denoising Albedo | Denoising Normal | | -- | -- | -- | | ![noisy.png](https://archive.blender.org/developer/F8678180/noisy.png) | ![noisy-albedo.png](https://archive.blender.org/developer/F8678182/noisy-albedo.png) | ![noisy-normal.png](https://archive.blender.org/developer/F8678186/noisy-normal.png) | The problem occurs when the material uses both low roughness and base color values, which could indicate an issue with how denoising data is handled with specular closures. I'm guessing that since denoising data updates for specular-like closures in `kernel_update_denoising_features` are deferred to the next bounce, but in this case the next bounce likely hits the background, it's never updated. @LukasStockner is more familiar with this code I think, maybe he could chime in?

Lukas Stockner commented

2020-07-10 03:24:50 +02:00

I guess the problem here is the heuristic used to determine where along the path to record the normal. Due to the Fresnel effect, the relative weights of the diffuse and specular parts change with viewing angle, so at shallow angles the code treats the surface as specular.

This is a known limitation, but I have no idea how to avoid it - we need to set the threshold somewhere. One approach would be to blend it or jitter the threshold, but that results in noisy normal/albedo passes. That causes problems with the NLM denoiser, maybe if Optix/OIDN is more robust to noisy feature passes we could enable it for them.

I guess the problem here is the heuristic used to determine where along the path to record the normal. Due to the Fresnel effect, the relative weights of the diffuse and specular parts change with viewing angle, so at shallow angles the code treats the surface as specular. This is a known limitation, but I have no idea how to avoid it - we need to set the threshold somewhere. One approach would be to blend it or jitter the threshold, but that results in noisy normal/albedo passes. That causes problems with the NLM denoiser, maybe if Optix/OIDN is more robust to noisy feature passes we could enable it for them.

Patrick Mours commented

2020-07-10 13:13:48 +02:00

AFAIK both OptiX/OIDN need noise-free normal/albedo passes too (I know for sure for OptiX). In this case the best solution I can think of is to use the OptiX denoiser with only the color pass as input (so to not confuse it with that albedo/normal data). That's currently only possible to select for final renders though (in the render layer properties), not for viewport denoising (which always uses color+albedo).

Fran Marz commented

2020-09-25 22:19:14 +02:00

Added subscriber: @franMarz

YAFU commented

2021-08-02 12:18:59 +02:00

Added subscriber: @YAFU

Philipp Oeser removed the

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Optix denoising is not working everywhere. #78571