LuxCoreRender Forums

Hi, i have again a problem with glass.
Unfortunately i cannot provide the luxcore scene. Hopefully someone knows already this kind of problem and can give me a explaination.

i have this scene with a display which has a glass cage on top. The glass cage is modelled with thickness and with no interesections between surfaces.
I told the glass to not cast shadows. I use this workaround in order to deal with bidir's caustics behind glass problem. Normally it works so i was expeccting to see it work even in this scene. The glass is a white glass with an attenuation at two meters.

This is what i get wen i render the display inside his oroginal space. All materials are simple diffuse white (0.7) exept some light emitting surfaces and the glass itself. As you see the glass keeps being extremely dark.


here the glass is turned off

By putting the display in a simplified space the result is correct

In maxwell by the way i get the correct result even in the original scene:

So i started to turn off one by one all lights of the scene.

Te only light which makes the glass not cast shadows are the big area lights i have outside the main opening.

then i turned off everything and added just a few spots with IES data on top of the cage: still the correct result.

I don't know how to get any wiser with these tests. In Maxwell, which has the same issues as Luxcore regarding caustics behind the glass, excluding the glass from casting shadows was the solution that helped get relatively credible results because the glass really stopped casting shadows. In Luxcore it seems that under certain conditions the glass continues to cast shadows.
Is it possible that we are doing something wrong? Has anyone else experienced situations like this?
Thanks for any help.

here the final results of both maxwell and luxcore

Luxcore:

Maxwell

At least this is what we are looking for.

Is there an other way to get that result under bidir?
Thanks again for any help.

Hi, here i share the geometry.
https://drive.google.com/file/d/1xf4b4k ... sp=sharing

Put whatever emitter to all layers starting with "emitter".
Put a clear glass to all layers starting with "vetro"
Put a white color in shadow output

in lux with bidir the best i get is this But i want to get a clear glass like this which comes from Maxwell What i'm doing wrong?

indeed the "white shadow" option seems to block more light as the architectural glass.

Architectural glass:
White shadow
Is there a workaround?

Here I have made the test between Archglass and Normal Glass+White_Shadow color.

Archglass Glass+Shadow color Edit Blendfile

https://drive.google.com/file/d/1YzhJdG ... sp=sharing

Hi dade, i need your help!

Sharlybg wrote: ↑Tue Oct 05, 2021 3:30 pm Here I have made the test between Archglass and Normal Glass+White_Shadow color.

Archglass
Bidir_ArchGlass.png

Glass+Shadow color
Bidir_Glass_Shadow.png

Edit Blendfile

https://drive.google.com/file/d/1YzhJdG ... sp=sharing

You have to reproduce the problem with a cube and, may be, a couple of walls: I can not track a problem in a scene with hundreds of objects. Try to errase everything is not relevant for the problem.

I isolated the problem! I think It has to do with light bounces on glossy surfaces.
I cannot upload the blender file, only obj, but the scene is very simple to replicate.

materials on obj layers
emitter= light emitting material
glass=clear glass with shadow output set to white
floor = white matte
box = white matte


here the layer "space" has a glossy light gray assigned.

here the layer "space" has a white matte applied.

It seems that the light bounced on the glossy surfaces is handled in a different way by the "shadow" output.

.obj are useless, the problem is not in the geometry, at least post the LuxCore scene if you can not post the .blend: .cfg, .scn, etc.

Hi dade, attached is the luxcore scene.