Strange light artifacts appearing

[David_Murgatroyd]

Hi,

Can anybody tell me what is happening in this scene? I've been having a problem with a semi-opaque object which is causing light areas where there should be shadow. See images below for comparison:



The above image shows a set of opaque louvres. I've excluded them from all GI operations so the only shadows they should cast are from the direct light in the scene only. The result above is exactly what I expected.



The only change in the above image is that the opacity of the material applied to the louvres has been reduced to 25 out of 100. The unexpected result is the bright spots in the shadow area! It's as if the orange box above is not even there. I'm baffled. All I can think it that the object is corrupted somehow?

Here's the link to the source file:

http://www.rockhunter.com.au/vrayfor...OW_PROBLEM.max

The small square semi-transparent object to the left of the louvres is an object I made in the scene. The louvres are imported from another scene.
If the louvres are indeed corrupt, how can they be "uncorrupted"?

[vlado]

Set the "Max transp. level" parameter in the Global switches rollout to more than 4 and it will be fine. The shadows of the transparent planes overlap and you can easily get 4 or more transparent surfaces behind one another along a shadow ray.

Best regards,
Vlado

[David_Murgatroyd]

Thanks Vlado, very quick reply! Just for future reference, the more overlapping planes, the the higher the "Max transp. level" has to be?

[vlado]

Thanks Vlado, very quick reply! Just for future reference, the more overlapping planes, the the higher the "Max transp. level" has to be?

Yes, that's correct. Older versions used to print a warning in that case, I think I will have to add it again, for user feedback.

Best regards,
Vlado