Noise patches

[lazardanilovic]

Hello, i have a problem where these patches of noise still exist even with small noise level, 1%. They seem to often be really uniform in shape, does anyone have idea what is causing this, bump, glossines, geometry?

I have one example bellow but it happens in random places from time to time.

Any input would be great, thank you!

[Avi]

Hi,

I have a few questions:

1. What version of Corona and 3ds Max you are using?
2. Are you using some HDRI or sun and sky to illuminate your scene?
3. Are you using some kind of reflection/refraction override in the scene?
4. When you re-render an image, the position of noise remains constant and doesn't change? In each re-rendering, the noise appears in the exact same spot every time instead of occurring randomly?
5. have you specifically changed any setting in the "performance" tab in render setup?

[lazardanilovic]

Hello Avi,

I am using Corona 9 with Max 22, in this instance i am using both HDRI for soft shadows and Corona Sun, but it happens even when I am only using either one of those. I am using reflection override, no changes in performance and yes, noise appears in the same spot and the same pattern on every render run.

Thank you

[aaouviz]

Hello Avi,

I am using Corona 9 with Max 22, in this instance i am using both HDRI for soft shadows and Corona Sun, but it happens even when I am only using either one of those. I am using reflection override, no changes in performance and yes, noise appears in the same spot and the same pattern on every render run.

Thank you

My guess is that there is either:
- 2 surfaces intersecting there
- A UVW mapping error
- A modelling error (overlapping faces or a flipped normal)

[romullus]

I would try to disable adaptive light solver and see if noise is gone.

[lazardanilovic]

Okay, I've done some digging and that noise patch matches perfectly with sun ray of another HDRI I have in my LightMix, so should i not have different HDRIs set up in my LightMix then?

[romullus]

If you're using lightmix, then make sure that your light intensities are not set to too high values, otherwise you may get noisy results. Scroll to the "what are the limitations" part in this article to read about this more. https://support.chaos.com/hc/en-us/articles/4528606952849-How-to-use-interactive-LightMix-in-Corona-for-3ds-Max-

[lazardanilovic]

If you're using lightmix, then make sure that your light intensities are not set to too high values, otherwise you may get noisy results. Scroll to the "what are the limitations" part in this article to read about this more. https://support.chaos.com/hc/en-us/articles/4528606952849-How-to-use-interactive-LightMix-in-Corona-for-3ds-Max-

Thank you, i will check it out!

[TomG]

Corona uses adaptivity, to prioritize which lights get more calculations in which areas of the image. In this case, your bright sunlight from the other HDRI is leading the way as needing the highest priority as "the most important light" for that area in the image, which results in other lights falling in that area getting less processing.

You could leave everything rendering until that patch clears up for the version where the sun patch is turned off.

Or you make all lights a similar intensity when rendering, e.g. this HDRI could be turned down in intensity so that it is "too dark", that way all lights get equal consideration. It may look odd in the Beauty, or even in single render elemetns, but you then render until the image is clean, and all lights will be equally clean, and you can adjust their intensities in LightMix to boost them back up, and there should be no noisy patches when a bright light source is turned off in LightMix.

Or you can turn off adaptivity, as another approach, forcing Corona to treat all lights equally anyway.

[lazardanilovic]

Corona uses adaptivity, to prioritize which lights get more calculations in which areas of the image. In this case, your bright sunlight from the other HDRI is leading the way as needing the highest priority as "the most important light" for that area in the image, which results in other lights falling in that area getting less processing.

You could leave everything rendering until that patch clears up for the version where the sun patch is turned off.

Or you make all lights a similar intensity when rendering, e.g. this HDRI could be turned down in intensity so that it is "too dark", that way all lights get equal consideration. It may look odd in the Beauty, or even in single render elemetns, but you then render until the image is clean, and all lights will be equally clean, and you can adjust their intensities in LightMix to boost them back up, and there should be no noisy patches when a bright light source is turned off in LightMix.

Or you can turn off adaptivity, as another approach, forcing Corona to treat all lights equally anyway.

Thank you Tom, this helped me understand a lot, i am fairly new at this so all these comments from you guys are of a great help. I've run a quick low-res render and sure enough no more noisy and burned out spots.