lights behind glass

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lacilaci
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lights behind glass

Post by lacilaci » Mon Jan 20, 2020 7:35 am

we can now hide lights behind arch glass, but those lights will show up behind any normal glass...
Due to this, I can have a softbox behind a "simple" window glass but any glass object or a proper glass pane system will show it... Big problem.

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lacilaci
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Re: lights behind glass

Post by lacilaci » Mon Jan 20, 2020 7:37 am

also related to light visibility, we can make shader/material to have disabled shadow but lights still do occlude other lights.
This means if I put a lightsource near wall, it will cast shadow on that wall.

kintuX
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Re: lights behind glass

Post by kintuX » Mon Jan 20, 2020 1:57 pm

set Opacity to 0

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lacilaci
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Re: lights behind glass

Post by lacilaci » Mon Jan 20, 2020 2:30 pm

kintuX wrote:
Mon Jan 20, 2020 1:57 pm
set Opacity to 0
where? I'm now talking about area lights in blender. There's no opacity control.

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Re: lights behind glass

Post by kintuX » Mon Jan 20, 2020 4:43 pm

Ah, no "real" mesh lights...
Guess you'll have to make a feature request then. ;)

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B.Y.O.B.
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Re: lights behind glass

Post by B.Y.O.B. » Mon Jan 20, 2020 5:00 pm

kintuX wrote:
Mon Jan 20, 2020 1:57 pm
set Opacity to 0
The problem about this is that you lose MIS.
This becomes apparent in glossy reflections/refractions like metal or rough glass.
In the attached scene there are two mesh lights: in the left half, with opacity = 1 and camera visibility disabled, in the right half with opacity = 0. The glass in front of the lights has shadow color white and the lower half is rough glass.
You can see the problems showing up in the form of undersampled glossy reflections (in the metal on top, and as fireflies from unresolved reflected caustics from the metal) and undersampled glossy refractions (the greenish rough glass).
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lacilaci
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Re: lights behind glass

Post by lacilaci » Mon Jan 20, 2020 5:51 pm

B.Y.O.B. wrote:
Mon Jan 20, 2020 5:00 pm
kintuX wrote:
Mon Jan 20, 2020 1:57 pm
set Opacity to 0
The problem about this is that you lose MIS.
This becomes apparent in glossy reflections/refractions like metal or rough glass.
In the attached scene there are two mesh lights: in the left half, with opacity = 1 and camera visibility disabled, in the right half with opacity = 0. The glass in front of the lights has shadow color white and the lower half is rough glass.
You can see the problems showing up in the form of undersampled glossy reflections (in the metal on top, and as fireflies from unresolved reflected caustics from the metal) and undersampled glossy refractions (the greenish rough glass).
Hm, any idea how cycles solves this issue? Cause I haven't seen any performance issues there with such features.

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Re: lights behind glass

Post by B.Y.O.B. » Tue Jan 21, 2020 1:55 pm

lacilaci wrote:
Mon Jan 20, 2020 5:51 pm
Hm, any idea how cycles solves this issue? Cause I haven't seen any performance issues there with such features.
I guess they have a different implementation of material transparency/opacity. It's a question for Dade if the LuxCore system could be changed in a way that allows MIS to work for fully transparent emissive materials.

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Re: lights behind glass

Post by kintuX » Tue Jan 21, 2020 11:31 pm

B.Y.O.B. wrote:
Mon Jan 20, 2020 5:00 pm
kintuX wrote:
Mon Jan 20, 2020 1:57 pm
set Opacity to 0
The problem about this is that you lose MIS.
This becomes apparent in glossy reflections/refractions like metal or rough glass.
In the attached scene there are two mesh lights: in the left half, with opacity = 1 and camera visibility disabled, in the right half with opacity = 0. The glass in front of the lights has shadow color white and the lower half is rough glass.
You can see the problems showing up in the form of undersampled glossy reflections (in the metal on top, and as fireflies from unresolved reflected caustics from the metal) and undersampled glossy refractions (the greenish rough glass).
Yes, aware of it... and I would simply rather render longer than spend time wishing for a goldfish to jump into my face. 'Cuz even then I'd need to master kung-fu or have humongous amount of luck, as they are quite slick and slippery, these sparkly little bastards :lol: ;)

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