Lightmix noise

[Vizoom]

Hello,

I don´t understand the lightmix:
-One image renders nice and after the render you´ve the possibility to save the image with interior lights switched on and another version with lights off inside the building for example
-Another image with lightmix  just doesn´t lose the noise, and after hours of render we see the disaster and have to restart the render without lightmix  and go the standard way = adjust the lights before and no adjustments afterwards!

It´s nice to use lightmix for previews, so we can change the sun-HDRIs and switch interior lights on/off for tests in the scene or previews...
But a time ago already I noticed that it´s not a good idea to have two or more hdris as different >light-selects< of lightmix in the final render as the image often just didn´t lose the noise...
So we now only have a sun light-HDRi and different groups of interior lights as light-selects, to adjust the lighting inside aftterwards...
But even this method is a risk: in the last projects finished two days ago I noticed after 3 hours of render that there just won´t be less noise. We stopped and switched the lightmix off, indeed it was the solution!... Next day I started this lightmix render again as a test and after 15 hours it was still noisy (particularly areas inside the building and glass objects) although the same scene (same lights but without lightmix!) was noisefree after 3-4 hours...
There is something wrong with lightmix.... to avoid surprices we will probabl only use it for testing/previews but avoid it in final renders now ...Really disappointing such usability problems :(...

Best, Artur / vizoom

[James Vella]

Are you setting a noise limit instead of a time/pass limit?

[Vizoom]

Are you setting a noise limit instead of a time/pass limit?

We had no time / pass / noise limits in the described case!

[bnji]

Hi there,
It would be better to provide screenshots, scene files, etc., to understand the issue better, as right now, we cannot be sure about the whole scene setup.
If you prefer, you can send us your scene project (including all assets) by submitting a support ticket instead.
We'll need as much information as possible to provide a more accurate POV/solution.
Looking forward to hearing from you.
Kind regards.

[Vizoom]

Hi there,
It would be better to provide screenshots, scene files, etc., to understand the issue better, as right now, we cannot be sure about the whole scene setup.
If you prefer, you can send us your scene project (including all assets) by submitting a support ticket instead.
We'll need as much information as possible to provide a more accurate POV/solution.
Looking forward to hearing from you.
Kind regards.

It is a competition entry, so I could send (or show) some files only when the results will be published...But we had the same problem in an older project (standard file needed some hours, lightmix version (with the same lights!!!) never(!) denoised)...I will  have to look for this file!

[TomG]

It is impossible to say without seeing images, or preferably the scene. For example, it is best if all lights are fairly similar in intensity if you are going to use LightMix (and you then set final intensities in the LightMix itself afterward), because if one light is extra bright, then due to adaptive sampling Corona will assign more importance to that light and less to the others. Then if you turn that extra bright light off in LightMix (and usually this would be a Sun), you might find there is noise in the parts of the scene that were illuminated by that light, because the other lights reaching that point in the scene were given less priority. Maybe that is something that is happening here.... or maybe not :) Without seeing some images, can't really say. You also have to be sure that denoising is turned on for every LightSelect, and you have to be sure to be using a recent version of Corona (earlier versions, from the early days of LightMix, could not denoise the "Rest/Unassigned" layer for instance), but other than that those kinds of situations, there is no reason why LightMix should not be as noise free as rendering without it.