Removing indirect light noise from existent render

[lupaz]

Hi,

I've been rendering an image for many hours. The indirect light pass has lots of noise and it's not going to disappear, ever.
Is it possible to change the settings (not sure what), and resume the render to correct that noise?

FYI: The render is mostly dark, with dark textures and materials.

Thanks.

[FrostKiwi]

If you resume render with strong noise, you will only start averaging new samples against old noise, which... how an average works... will take a very long time. If it's fireflies, then you can filter them out with the Firefly denoise option, or generally you can slap denoise over it. But better yet, find the reason for the apperently unreasonable amount of noise.
Are you on default settings?
Can you post an image, to get an idea of the scene?

The noise reason can depend on many many things, it is difficult to assess that without a picture. Otherwise refer to the official corona freshdesk for general Noise FAQ:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983-how-to-get-rid-of-excessive-noise-

edit:
If it's just a small region you can region render that spot, but better find the source of the problem. Are you on 1.4 dailies or 1.3?

[lupaz]

Thanks for the response.

This is the image:
http://cl.ly/3U2n2Y1Y2P3S

And the detailed area:
http://cl.ly/0R1n0p3X381Q

This is the indirect lighting pass, same area:
http://cl.ly/3j1k0X1P3x0x

This is the only pass with noise as far as I can tell.

I'm on default settings.
I have DOF checked, but the detailed area shown above is in the focus region.
The scene is lit only with sun and sky, using light portal material on planes placed on the openings.

I'd add more samples to the sky or the light portal material...Any way to do this?


"But better yet, find the reason for the apperently unreasonable amount of noise."

It's the chicken and the egg case. I need to render for a while to find out this type of noise. Otherwise I just think it's noise due to lack of rendering time. no?
I am used to this process of trial and error. I just was hoping there was the option of changing settings on the fly, and resuming with the saved EXR.

[JoeVallard]

I'd suggest jumping over here https://forum.corona-renderer.com/index.php/topic,7239.0.htmland try the daily build. The Denoise feature does a very good job at removing noise, without the lose of details in textures.

[maru]

My guess would be that the noise is caused by having a lot of reflective surfaces (reflective caustics). One solution would be using rayswitch material to make the materials less reflective to GI rays, but it could be painful to alter many of them. Another idea is to lower MSI.
Hopefully the new adaptivity and denoising will be able to cope with such noise.

[lupaz]

I'm not sure I understand. Are there caustics by default?
I didn't turn them on on my materials...

[FrostKiwi]

I'm not sure I understand. Are there caustics by default?
I didn't turn them on on my materials...

Refractive caustics are off by dedault , but reflective caustics are always on.

[lupaz]

Is this reflective caustics or simply radiance?

In other words, if I have a concave reflective surface, the rays will actually focus on a point by default?

[maru]

Corona is physically-based, so if it happens in real life, it will also happen in Corona. Reflective surfaces always reflect some light. The brightest reflections are usually "cut off" by Max Sample Intensity (https://coronarenderer.freshdesk.com/support/solutions/articles/5000515636), but still some of the caustics could be visible.

[vedat.afuzi.design]

Hello guys,

I just wanted to give you my quick feedback about this and some features in Corona Renderer:

I am a long-time user of Corona Renderer, and I would like to share some constructive feedback aimed at enhancing the user experience.

I understand Corona's commitment to a physically-based approach, and I appreciate its uniqueness. However, I find that offering more flexibility, akin to other renderers like V-Ray, would be highly beneficial. Specifically, having the option to disable certain features or effects, such as refractive and reflection caustics, would empower artists to achieve varied creative demands more efficiently.

The separation of reflection and specularity is another critical feature that, at times, necessitates the use of alternate renderers to meet specific project requirements. It would be invaluable to have such flexibility within Corona to better align the renderer with diverse creative visions from the inception of projects.

While I have observed and appreciated numerous feature enhancements, I’ve also noticed a slowdown in rendering times, even for relatively simple scenes, on powerful workstations. Addressing this would greatly enhance the overall user experience and efficiency.

I hope my suggestions are seen as constructive input from a dedicated and appreciative user. I’m eager to see Corona Renderer evolve to meet the growing needs of the 3D artist community and look forward to continued advancements.

Thank you for considering my feedback. I remain a loyal user and am excited to witness future developments.

Warm regards,
Vedat