Probabilistic lights problem

[fco3d]

Hello,
I have this issue with probabilistic lights, I am using latest Max release and latest update for V Ray 3.
in some scenes were all the lights are in view, probabilistic lights seems to render OK, not major difference on rendering time when on or off.
But when I render other scenes with light outside of the camera view, it seems to be more Noise in the light pass. I am using Irradiance and LC with the default shade rates of 6 and AA 1-24. To eliminate the noise on the lights I need to increase the AA to number that make my render times unacceptable.

If I turn off probabilistic lights, the scene cleans almost instantly but it take 2 times longer to render glossy areas. with same settings. All what I am doing is turn on or off probabilistic lights.
Is there a reason for this? work around, I am missing something?

Your help is appreciated.

[Lupaz]

In my experience this is how probabilistic lights work, and it was never fixed.
as soon as I see bright spots in the scene that won't go away, I know I need to turn prob lights off.

[fco3d]

Thanks for the reply, I did more test and I would like to know if what I find out, is correct.
I am using all default values for V-Ray, only playing a little with the Noise threshold in AA.
I found that, when I increase the number of light in Probabilistic light control, the noise is reduced and also the rendering time. The optimum value seems to about the same number of lights in your scene, in my case 180. Any number under that create noise; and make the AA work more in those areas. When the light number is matched, the antialising just fly over and only work on glossy samples.
Is this correct?

[vlado]

But when I render other scenes with light outside of the camera view, it seems to be more Noise in the light pass.

Well, we definitely have more work to do on this... If you have a scene that we can use for testing, it will be very helpful.

Best regards,
Vlado

[fco3d]

Thanks Vlado, I'll talk with the boss here and see what we can send

[Jiri.Matys]

I found out probabilistic lights make more noise every time in every scene. I disable it every time.

[eyepiz]

IES Lights HATE probabilistic.

Vlado, I sent you a scene last month at you request. I haven't herd back.

http://forums.chaosgroup.com/showthr...743#post678743

[vlado]

Vlado, I sent you a scene last month at you request. I haven't herd back.

Yep, I got it. I have some ideas for improving the sampling, but I haven't gotten round to it yet.

Best regards,
Vlado

[snivlem]

I thought I should post here instead of a new thread.

But one thing I've noticed is that with probabilistic lights on, it will sometimes choose to ignore V-Ray sky when doing interiors. It seems to be pretty low on the priority too as I had to crank up the amount of probabilistic lights in order for the sky to render again but the amount ruled out the benefits of using probabilistic lights.

[vlado]

This is very odd; if you have a scene where this is reproducible, can you attach it here ot send to support@chaosgroup.com? Direct lights and dome lights are generally excluded from the probabilistic sampling.

Best regards,
Vlado

[snivlem]

Will do, I'll link back to this thread.

Sorry that this is a Maya bug in a 3DS Max forum though, I didn't expect it to be a "bug".