Large difference in brightness between luxcore 2.2 and 2.3beta1

Use this forum for general user support and related questions.
chafouin
Posts: 99
Joined: Wed Jan 24, 2018 9:35 pm
Location: Los Angeles

Re: Large difference in brightness between luxcore 2.2 and 2.3beta1

Post by chafouin » Sat Feb 01, 2020 6:48 am

I found the "problem", you need to enable Normalize on your Blackbody. This is weird because to match 2.2 behavior, Normalize should be off...

What I also noticed is that Emission nodes were probably always normalized by color luminance in 2.2. So if you want to match the exact same brightness, you will have to check that box in 2.3.
I think that this should stay off by default for the Power unit and I wouldn't recommend changing its defaut to match 2.2 behavior, to unify the workflow between lights and emission nodes.

EDIT: The two normalize are fighting a bit against each other. Normalizing by color luminance in the Emission node will in fact change the range of the Blackbody to 0-1, but it will also apply a luminous efficiency curve that will normalize based on the color.
The Normalize in the Blackbody Temperature will only change its range to 0-1.
Last edited by chafouin on Sat Feb 01, 2020 7:26 am, edited 5 times in total.

kriscreative
Posts: 7
Joined: Fri Jan 31, 2020 7:16 am
Location: Hokkaido, Japan

Re: Large difference in brightness between luxcore 2.2 and 2.3beta1

Post by kriscreative » Sat Feb 01, 2020 7:13 am

Thank you! Just ticking normalize on the black body radiation node brings my interior scene close enough to what I was looking for. As suggested will keep the normalize mode off for the emission nodes.

chafouin
Posts: 99
Joined: Wed Jan 24, 2018 9:35 pm
Location: Los Angeles

Re: Large difference in brightness between luxcore 2.2 and 2.3beta1

Post by chafouin » Sat Feb 01, 2020 7:36 am

B.Y.O.B. wrote:
Sat Feb 01, 2020 1:00 am
Maybe it's related to the fix of gain + power/efficacy settings?
I think we are facing a bit of dilemma here: better default settings vs maintaining legacy.
2.2: Blackbody isn't normalized, Power in Emission nodes is normalize, Power in Lights isn't normalized.
2.3 current: Blackbody isn't normalized, Power in Emission and Lights isn't normalized -> Emission nodes are exploding

Best way to fix it: assume that Blackbody was always used with Emission nodes and set its default Normalize value to 1 (which is artist friendly), keep Power in Emission and Lights not normalized -> Emission nodes won't explode, but renders will be slightly different from 2.2 as the luminous efficiency curve won't be applied (which is correct).
Then we inform artists that if they want 2.2 renders that use Blackbody to look identical in 2.3, then they need to check Normalize by Color luminance in the Emission node.

User avatar
B.Y.O.B.
Developer
Posts: 3599
Joined: Mon Dec 04, 2017 10:08 pm
Location: Germany
Contact:

Re: Large difference in brightness between luxcore 2.2 and 2.3beta1

Post by B.Y.O.B. » Sat Feb 01, 2020 12:09 pm

chafouin wrote:
Sat Feb 01, 2020 7:36 am
Best way to fix it: assume that Blackbody was always used with Emission nodes and set its default Normalize value to 1 (which is artist friendly), keep Power in Emission and Lights not normalized -> Emission nodes won't explode, but renders will be slightly different from 2.2 as the luminous efficiency curve won't be applied (which is correct).
Then we inform artists that if they want 2.2 renders that use Blackbody to look identical in 2.3, then they need to check Normalize by Color luminance in the Emission node.
Sounds good to me. Will you do a pull request or should I implement these changes?
For this release, the slogan is "better default settings" for sure, since we are already breaking backwards compatibility. Better to do as much of that as possible in one release, so the next ones don't need to do it.

Post Reply