Vray Light Select Bug

[sebbiej]

Hi all,

I think I've come across a bit of a bug with V-Ray 3.0 (running it in Maya 2015 SP6 Extension)...

I've got an interior scene that has got quite a lot of lights in it, comprised of 51 Vray Rect Lights that simulate day light and interior strip lights, and then 26 IES Lights that are used for spot lights.

I'm trying to split these lights out in to a few separate Light Select render elements so I can control them in post and I'm having some problems getting it to do it correctly.

I've got a 7 light select elements for the rectangle lights, and these render fine, but when I add another that just contains the IES lights, all of the light select elements render just black. The lights show fine in the RGB Color pass, but they won't show any of the light select elements.

In doing some playing around with it, this extra light select element seems to work if I only have 4 IES lights visible (and hide the rest), but if I add any more it just renders black on all light select elements.

Is this a bug? Am I doing something wrong? Have I exceeded the amount of lights or something?

It's also happening on a similar scene that a colleague is currently working on.

Need help asap if anyone knows the answer .

Thanks!

[sebbiej]

Actually scrap that... I just figured out the answer!

The Probablistic lights setting was set to 64 in my scene, if I set that to the actual amount of lights in the scene (86) then it renders out correctly!

Wahoo!

[yolov]

That's actually a bug, this shouldn't happen at all. I've made a note in our bug-tracking system to fix this.

[sebbiej]

Ah I see! Glad I pointed it out then .

Am I right in thinking the Probablistic lights should be set to the actual number of lights in the scene anyway? As in for the speed benefit of them? (If that bug wasn't there...)

[yolov]

Yes, thank you for reporting this.

Probabilistic lights allows you to specify the number of lights to be sampled, which typically should be less than the number of lights in the scene in order to speed up the rendering. Setting it to the exact number of lights in the scene would mean you're not taking advantage of it. A typical case would be having 80 lights in the scene, setting "probabilistic" to anywhere between 8-20 (for example), lighting contribution stays the same, but instead of 80, only 16-20 lights get sampled and the render goes faster.

[sebbiej]

Ahh I see, thanks for clearing that up for me! I'll give that a try and see if that can speed up the renders that we are creating.

Thanks,

Seb