Author Topic: Light Mix Units and Denoising  (Read 3516 times)

2017-10-23, 12:23:38

studiobasler

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Hello Forum,
so Iam new to Corona and first of all its very intuitiv and im happy with my first results.
Raising up the Light mix Values ends up in a very noisy image althought i checked the "Apply denoising" to it.
So im using Light mix to find the corrct light intensity and would like to know the corresponging units so i'am able to
feed my lumen Value. If i raise up the Light Mix value for example to 6, what value do i have to insert in my lumen intensity to get the same intensity?

Thank you
Christian

2017-10-23, 12:46:06
Reply #1

PROH

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Hi. 2 things about Lightmix:

1) - As you already found out, rising the level will result in more noise. So in general you shouldn't rise the level, but lower it. So set your light a bit to high or at their max level, and then lower the values in lightmix.

2) - You can send your lightmix changes back to the scene by the push of a button, so you don't need to know the lumen values to do this (can't remember the exact name of this function, and can't open Max right now).

Hope it helps

2017-10-23, 13:01:51
Reply #2

TomG

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It's the ">Scene" button :)

For the original poster, you can read information on LightMix over at https://coronarenderer.freshdesk.com/support/solutions/articles/12000017218-how-to-use-interactive-lightmix- which covers both the question of why it is noisy if you raise the light values too much, and where to find the >Scene and other buttons.

2017-10-24, 13:19:24
Reply #3

studiobasler

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Thanks you both for your input.
I did a test with the light mix, but it has no effect. First i render the image and do my adjustments in LightMix. Then i click ">Scene" and re render the image, but there arent any changes. All my settings in the LightMix are gone to 1 and in the rerendered image are the same light intensitys as before.

Further on i get these "black fireflies" and i have no idea why. At the beginning of the render process there arent any of these black dots, but later on they appear suddenly. If i remove the Light sources, the black dots do not appear. Maybe my light sources have to much intensity (Lumen 5000)?

Cheers


2017-10-24, 13:25:15
Reply #4

PROH

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Hi. I'm not a C4D user, but in Max the "black dot" problem might be solved in RC9 (looks like you are using RC8).

Edit: Just tried the lightmix "Scene" function, and in Max RC9 it works.
« Last Edit: 2017-10-24, 13:46:33 by PROH »

2017-10-24, 15:34:03
Reply #5

studiobasler

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ok, but there isnt any RC9 for C4D or am i wrong?

2017-10-24, 15:48:07
Reply #6

maru

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2017-10-24, 18:34:22
Reply #7

studiobasler

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just uploading, thanks. Can you also check the LightMix Issue?

Thank you
Christian

2017-10-25, 11:36:24
Reply #8

maru

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just uploading, thanks. Can you also check the LightMix Issue?

Have you uploaded the scene? What is the file name?

What is the LightMix issue specifically? I can see that some of your questions are already answered in this thread.
-increasing intensities drastically may introduce noise and this is expected - https://coronarenderer.freshdesk.com/support/solutions/articles/12000017218
->Scene button should bake the intensities into scene lights - if it does not work, it means it is not yet supported in the C4D version
-if light intensity is X, and you set intensity from 1 to 5 in LightMix, then you need to set light intensity in scene to 5*X to get the same result (there may be still some differences, for example because of MSI - https://coronarenderer.freshdesk.com/support/solutions/articles/5000515636-what-is-max-sample-intensity-msi-)

2017-10-25, 12:34:58
Reply #9

studiobasler

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Hello maru,
yes uploaded the file yesterday, i thought you would be informed automaticly. Because of File size i uploaded it into my dropbox: Christian Basler - CoronaExport.rar
Did you get any further information on that?

Cheers
Christian 

2017-10-25, 14:10:30
Reply #10

TomG

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From a quick test scene of my own, it seems like >Scene will bake light color back into the scene, and will correctly reduce light intensities, but will not raise light intensities.

2017-11-16, 11:17:47
Reply #11

maru

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From a quick test scene of my own, it seems like >Scene will bake light color back into the scene, and will correctly reduce light intensities, but will not raise light intensities.
I just tested this with the newest daily build, and it's still the case. Lowering light intensity in LightMix and then >Scene works fine, but increasing it and then >Scene does not do anything.

Other than that, I do not think LightMix is supposed to be used in such precise way that it would allow using some real world light intensity units. It is rather intended for artistic control, tweaking light intensities to taste, etc.

2017-11-16, 12:21:45
Reply #12

houska

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Other than that, I do not think LightMix is supposed to be used in such precise way that it would allow using some real world light intensity units. It is rather intended for artistic control, tweaking light intensities to taste, etc.

Well, it will do a relative tweaking, so if your light was 10000 Lumen to begin with, if you set the LightMix intensity to 2.5, and bake it into the scene, the result will be 25000 Lumen. There's no black magic involved in the math :-)

2017-11-16, 13:53:29
Reply #13

4b4

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how do things work with HDRI exposure levels?

2017-11-16, 14:32:32
Reply #14

houska

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how do things work with HDRI exposure levels?

What do you mean? Can you rephrase your question so that it contains more information? Thanks