World volume + PGI = rerror

[Rivental1]

Hello!
Luxcore 2.3 beta 2.
Blender 2.81
When i use PGI or DLSC with world volume (homogeneous) my render is freeze (when cash computing) after some time i have to close blender.
It's happen only when i use world volume. When i use cashes with other volumetric objects everything ok.

[Dade]

Luxcore 2.3 beta 2.
Blender 2.81
When i use PGI or DLSC with world volume (homogeneous) my render is freeze (when cash computing) after some time i have to close blender.
It's happen only when i use world volume. When i use cashes with other volumetric objects everything ok.

Can you post a simple test scene showing the problem ?

[Rivental1]

Of course...

[Dade]

Of course...

Ok, it is not really frozen, PGI is just trying to process an enormous (1,000,000+) number of cache entries: this happens because you have the cache enabled on the air volume and the volume is assigned to world so it has an infinite extend. PGI is basically trying to cover an infinite amount of space with cache entries and, indeed, it takes for ever.

To work around the problem, you can create a box around the scene with NULL material (or solid if it is far enough to not be visible due the scattering) and assign the volume to the box so the volume has a finite extension.

The other option is to just disable PGI on the volume however I have found a bug in beta2 and the BlendLuxCore setting had no effect. It is now fixed but you need the next daily build to be able to use this option.

P.S. BlendLuxCore could probably fire an warning, using PGI for world volume is nearly always a bad idea (if you are not in a closed environment).

[B.Y.O.B.]

P.S. BlendLuxCore could probably fire an warning, using PGI for world volume is nearly always a bad idea (if you are not in a closed environment).

I can do that.
Maybe it would also be a good idea to set the "Use PhotonGI Cache" checkbox on volumes to disabled by default?

[B.Y.O.B.]

PhotonGI on volumes is now disabled by default. Warnings are shown if a volume with enabled PhotonGI is used as world volume.

[Dade]

P.S. BlendLuxCore could probably fire an warning, using PGI for world volume is nearly always a bad idea (if you are not in a closed environment).

I can do that.
Maybe it would also be a good idea to set the "Use PhotonGI Cache" checkbox on volumes to disabled by default?

Yup.

[Rivental1]

Thanks! I hope this solution can be helpful for someone else.