Light in the box lights up also outside

[3DKodo]

Hello, I have encountered a problem and i've just opened a ticket but if anyone had same problem....
if I have a light in a box, it also lights up outside the box.
you can find a simple test scene in attach and a jpg for example!

Some advice?

...I use 3DSMax 2023 + Corona 9 hotfix 1

[romullus]

Hi,

Try to add thickness to the box walls - light penetration should be completely eliminated.

[3DKodo]

Hi, thanks but it has already a thickness..

[romullus]

I have looked at your scene and indeed there is a light leakage even with the wall thickness. I don't see any obvious mistakes in the scene, however i would recommend to reset render settings. By doing that, i was able to eliminate most of the leakage. If there is still some light visible outside, you can increase UHD cache precision to 2.0 or so, until there is no visible light leakage. You will find the setting in render setup>performance>UHD cache rollout. Alternatively, you can switch secondary solver from UHD cache to 4K cache - this should eliminate leakage completely even at default settings.

[Aram Avetisyan]

This is caused by UHDCache. Doing Render Settings > Scene > Reset settings may help but note completely.
As romullus mentioned, changing the secondary solver to 4k Cache or Path Tracing will solve the issue.

This is reported for UHDCache improvements.

(Internal ID=1032886469)

[3DKodo]

Thanks to all!!
it work in all way to resolve the problem!