Lighting element problem

[RichardBlank]

Lately we've had a lot of strange problems with the lighting RE. Sometimes one of the lights, mostly vrayLightRects, cuts off the other lights. We started to get this problem about a month ago. We have tried the latest nightlies and the latest stable versions, but in some scenes we cant get rid of the problem.
Attaching a sample scene. Render this with IPR and the lighting pass gets cut off. But in other larger scenes we get the problem with the regular renderer and standalone.

[tashko.zashev]

It looks like a different behavior for already known bug. The same light cut-out will occur for production V-Ray renderings with reflective V-Ray materials and multiple light sources. I see your scene uses Lambert shader for the ground.
There is a workaround for this issue which you can use until the fixed builds came out.
* add another light source to the scene - sphere light for an example; untick Affect Diffuse, Specular, Reflection ; and make it invisible

[RichardBlank]

Ok, thanks for the tip. We found out that you also need to check No Decay. Hopefully this gets fixed soon

[sharktacos]

I reported two similar bugs involving the lighting RE. Reverting to Vray 3.4.02 should fix it (that's what we ended up doing).

[vlado]

Thanks a lot for the scene! I think I know what causes it, so hopefully I can get you a fix soon.

Best regards,
Vlado

[vlado]

This is fixed for the next nightly/stable build (hopefully tomorrow).

Best regards,
Vlado

[Fredrik Averpil]

Hey Richard!

We just hit this bug today as well. The stable from Oct 5 has this fixed and our scenes are rendering without this issue.

Again, thanks Vlado & devs!

[Algehov]

As Fredrik mentioned above, we hit on this bug a few days ago. It came from nowhere as the scenes has rendered correctly through quite a few iterations, which I find odd, and it started popping up in a couple of projects.
However, upgrading to the latest stable fixed the issue. But it turns out it introduced a different issue instead.
Two sided materials seems to get blown out in the lighting element.

See below:


I've recreated the issue in a simple scene, but the behavior of the lighting pass seems to change depending on how you tweak the material, or turn the object/move lights. Sometimes the problem is barely visibly. And sometimes it gets really bad. It never looks wrong the beauty render however. Only the lighting pass.
Here is how the test scene renders for me:


And here is the scene
Maya 2016 ext1 sp5
Vray 3.40.04-b2670-stable
https://mega.nz/#!ewAxjZxJ!rAPpz6zw6...VvQD7mf_mZUAp0

Thanks in advance,
Simon

[Algehov]

To add to what I wrote above. This seems to only be an issue if you have reflections on the sub material of a 2sided mtl. If I turn off reflections, the lighting element looks correct.

[Mihail.Djurev]

This should be fixed in the latest stable nightly, could you check it out? If everything works fine, we'll include the fix in the next patch.

[Algehov]

Yes, we heard from Vlado that this was fixed in both the latest nightlies, and the latest stable (from yesterday?). We tried it out, and it has been working great on both. We had our deadline today and it saved us quite a hefty bit of comp fix headache, so cheers for that!

[Fredrik Averpil]

From what I've heard (right, @Algehov?) it's fixed in the latest stable build, yes!

EDIT: whoops, too slow!