Handling Brute Force noises

[RwVision]

Hi,

Since Vray 5 forces now the use of BRLC method, my worst nightmare comes back - ugly, unbalanced image noise

90% of image is ok, 10% (mostly unlit corners) has x5 times more noise, which only improves with lowering threshold - but still stays visible, where the rest of the image is clean and rendering times skyrockets.
(This is where the latest IRLC method with detail enhancement was superior sometimes)

How do you handle those noises?
(Please don't mention any denoising methods.)

Exterior scene, Vray Sun with sky.
Walls contain only diffuse noise, no reflections. If somebody is curious I can export a scene, but it's rather common setup.

Threshold 0.02 (raising min/max subdivs does not change nothing here )




Threshold 0.005 (better - but still not acceptable + long rendering time)



Will appreciate any tips

[YunalZobu]

I don't mind having a look on your scene, since I wasn't successful trying to recreate the "unbalanced" noise distribution.
Render times are trickier to compare, but these shots have displacement on the base wall and similar (I guess) to your diffuse noise setup.

[RwVision]

Thanks for the interest Yunal.
Basically, what you did is heavy bump, which looks in distance like noise. So hard to spot the GI noise, but it is there.
Scene also needs little more complexity.

Most of the scene is on current setting acceptable to the eye, but the balcony corners, shadow parts stand out dramatically. For me it's a common problem wit Brute Force. Even on 3.7 I tried to switch from IRLC to BRLC, but many interiors just had those ugly spots, no matter how long would you render. Wondering why min aa setting does not help here?

Leaving you soon a link to scene on private message. Try with higher settings. Just render as is 0 frame:

[xpez]

Why isn't denoising part of the discussion? denoising might be very useful in this situation. If it doesnt produce more artifacts it seems to be useful in a situation like this. I have met some people who think denoiser is a band-aid solution to the real problem. But I see it like this. If you spent hours trying to get rid of the noise and a cheap solution is denoising and the final solution without denoising looks identical to denoising, then it really begs the question of why fussing with the settings if denoising settles it instantly. I am sick of waiting on renders to solve this stuff. If denoising does it and it looks awesome and I can move on to something else then HELL YEAH I LOVE DENOISER!!!

[RwVision]

HELL YEAH I LOVE DENOISER!!!

Thanks for the input,

Well, I loved denoiser too - back when it worked
But this topic is about understanding and learning the base Vray 5 GI engine. Which further can implement denoising also.

If you want to enter current denoiser discussion, please post your examples on my different topic. I will really appreciate this:
https://forums.chaosgroup.com/forum/v-ray-for-cinema-4d/v-ray-for-cinema-4d-general/1095347-multipass-denoiser-performance-2017-vs-2020

To answer your question quickly:

- Denoiser is just not capable of denoising, without loosing details and strong blush.
- Denoiser isn't selective, so getting rid of that small portion noise, will destroy the whole image.
- This topic should also interest you. As mentioned, I'm also a big believer in multipass denoise, but even then you must ensure that your scene is evenly noised. Only then, you can successfully raise the aa threshold and then denoise, without loosing the quality.
(I've used the standalone denoiser to drastically reduce rendering times in animations almost since it came out for c4d - but with IRLC and old mp denoiser)

- Vray as a professional rendering engine should be able to produce clean, even renderings. Since BR method is now forced, it should be perfect for anything.

From my experience, BR is very faulty in this topics matter (talking years, even before 3.7). But if someone points out that where my setup is wrong, I will be mostly glad

[xpez]

thanks for your concise answer. I appreciate it. I see you points about changing the direction of the conversation! I will think about that moving forward.

[shaio]

Hi RwVision
is it possible for me to get a link to the scene as well? I'd like to take a look at it as well since I've recreated something similar here, but I can't really get the same noise.
Do you get the same amount of noise when you have the noise threshold to something like 0.005 with the default 1 and 24 min/max subdivisions or with new default settings preset? Do you get the same amount of noise when you do a global material override with a gray or white material?

[sirio76]

Hi Ivan,
I'll try to send you a scene as well, I'll also investigate the difference between old denoiser and new one because as noted by RwVision on Vray5 is very bad at preserving details, it almost seems like it do not read some of the render elements while denoising ( diffuse filter, noise levels etc).

[RwVision]

Hi RwVision
is it possible for me to get a link to the scene as well? I'd like to take a look at it as well since I've recreated something similar here, but I can't really get the same noise.
Do you get the same amount of noise when you have the noise threshold to something like 0.005 with the default 1 and 24 min/max subdivisions or with new default settings preset? Do you get the same amount of noise when you do a global material override with a gray or white material?

Hello Ivan,

I've attached before similar example, but here's 0.005 min 1 max 24 aa - nothing changes. With those settings every image should be already CLEAN:



I can't find the material override option (why isn't it in Overrides -> Materials??), so please check for yourself.

[shaio]

I've attached before similar example, but here's 0.005 min 1 max 24 aa - nothing changes. With those settings every image should be already CLEAN:

Hi RwVision ,

Thank you for the scene. I've made some tests and to me, it seems like the Bump amount of the material (0.65cm) and having Noise shaders in both Bump and Diffuse is also heavily impacting the image looking noisier. I've created a new Render Settings preset to avoid any unwanted legacy settings if the scene was converted and the only few parameters I changed are the Noise Threshold from 0.01 to 0.005 and the Sampler from Progressive to Bucket.

Here are tree renders from the scene that you send me where one of them is a straight render without material tweaks, the second one has a lowered Bump amount (from 0.65 cm to 0.1 cm) and the third one is without the noise shader in the Diffuse channel so you can see the amount of noise produced by the sampler.







In my opinion the Noise shaders in the materials need to be tweaked to achieve a cleaner result since the noise isn't primarily produced by V-Ray. If you want even cleaner result feel free to lower the noise threshold to something like 0.003. Since you're not using a denoiser here are some raw render times from my tests to give you an idea on how long the rendering takes.

Noise threshold: 0.01 - 1m : 30 s
Noise threshold: 0.005 - 2m :10 s
Noise threshold: 0.003 - 2m :40 s

Let me know if this works for you.

[RwVision]

Many thanks Ivan,

(The whole scene was created as new in V5, so no changes here.)

Basically, that's not an answer - 0.005 is already way too long to render, compared to other sections of the image.

Diffuse noise must stay and it's not the main problem.
GI noise is still present in those areas. If we would use old IRLC method with detail enhancement we would have long gone those noisy areas.
Whole problem lies in those tiny areas, which force unnecessary calculations on the "easier" parts of image.

Please look closely on roof corner, where there's no noise shader in diffuse - whether it's 0.005 or 0.003, it's still noisy:



Could you post and test render times with no overrides? ( And where's the override setting )

[shaio]

Could you post and test render times with no overrides?

Do you mean to test render times without overriding the Render Settings and/or the Materials on your scene?

[RwVision]

Yes, please.

IfVray5 wouldn't be all automatic, I wonder if altering settings from 3.7 would help.
Overall, BR is just still very uneven in some situations - Rendering an aircraft cabin interior with BR is just an overkill for noise and times - even with denoising.

[shaio]

I did another rendering, and before I share the results It's a good idea to clear out that on my previous tests above the resolution was 1280x720 and not 1920x1080 because of the Render Settings override. Also, the images I posted were only a region rendering not the full image as the current test.
Here is the render time I got from your current project settings - 1080p/Bucket/MinSubdivs=1/ MaxSubdivs=7/NoiseThreshold=0.015/ no Antialiasing / no textures as the pictures above): - 4m : 55s for frame 3.

[RwVision]

Hi Ivan,

I really appreciate your taken time.
If you could, please render the whole image with textures and no overrides. Then, make the same scene with your AA settings, which get rid of the noise completely. Do not change any shaders.

We will compare the quality->time needed for clean image.