Author Topic: Corona 7 vs 8 Lighting Temperature Differences  (Read 1725 times)

2022-05-19, 11:08:00

jaspercrowe

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Hi,

I noticed that lighting temperature applied via lightmix has changed in the latest version of Corona. Has the update attempted to make temperature changes more realistic, or is this an unintented change?

Comparing outputs from 7 and Keyshot vs 8, warmer colour temperatures are a lot less saturated in the new version.

2022-05-19, 11:22:28
Reply #1

maru

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Hi, we are aware of this and investigating whether there is some explanation to this or if it was unintentional. I will be sure to update you here once we know more.

(Report ID=CRMAX-1615)
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2022-05-23, 11:38:39
Reply #2

jaspercrowe

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Hi Maru,

Just wondering if there's an update on this? I think I've discovered what the difference in the values is.

The temperature in Corona 8's VFB appear to be outputting values using linear colour space, and the old VFB version was outputting the same numbers, but in gamma corrected sRGB. CoronaColor still outputs in sRGB for temperature values.

It would be great if this could be corrected (whatever way that is haha, not sure which is more physically accurate) in the first hotfix. I'm doing some work for a client that requires relatively high colour accuracy, but guess I'll roll back to 7 until this is sorted.
« Last Edit: 2022-05-23, 12:45:02 by jaspercrowe »

2022-05-27, 10:54:18
Reply #3

Dionysios.TS

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Hi, I've noticed weird things with the color temperature values as well.

A Corona Light with a 3.000°K temp produces different results if compared to a Corona Light Material with the same value. The latest one, (Corona Light Material) is less saturated.
To bypass this I put a CoronaColor map in it's color slot and there is something wrong here in any case.

Thanks,

Dionysios -

2022-05-27, 14:21:49
Reply #4

maru

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There is a bug in V8. It is applying gamma correction twice on the color computed from black-body radiation. This is internally fixed so that it should behave the same as in Corona 7 and the fix will be included in the upcoming hotfix. 
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2022-05-27, 15:25:50
Reply #5

aaouviz

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Just chiming in here with a potential bug I experience:

If I type in a temp value and press OK/enter, the light color doesn't change. It just defaults back to white or the previous color.

If I use the slider, the temp works as expected.

Is this replicable for others? Cheers!
Nicolas Pratt
Another Angle 3D
https://www.instagram.com/anotherangle3d/

2022-05-30, 12:57:26
Reply #6

maru

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The main issue is fixed in the newest Corona 9 daily build:
https://forum.corona-renderer.com/index.php?topic=36810.msg199437#msg199437

This will also be a part of the upcoming hotfix.

About the other issue:
Just chiming in here with a potential bug I experience:

If I type in a temp value and press OK/enter, the light color doesn't change. It just defaults back to white or the previous color.

If I use the slider, the temp works as expected.

Is this replicable for others? Cheers!

We will test this.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us