Small / far away lights disappearing and appearing in animations.

[JD3D_CGI]

I have an animation with lots of lights, and some of them seem to be appearing and disappearing during the animation.

I'm using brute force/brute force.

The lights are sometimes behind glass or water...

What can help fix this?

[vladimir_krastev]

Hi, thanks for posting. Increasing the resolution and increasing the subdivs of the image sampler should help. Please check this thread and this article. Some if the advice there may help in your case.
Try to increase the number of adaptive lights (the default is 8 ) and see if this helps. You could also send us the scene for review. Please if you choose this option try to simplify the scene as much as possible, removing everything that is not necessary for demonstrating the issue.

[JD3D_CGI]

Thanks - so it's not fireflies which are the problem, it's lights seeming to appear and disappear.
I have gotten to understand using the Sample Rate and Noise render elements and so I have 900000 samples in the scene - no noise.

It's more like Vray can't decide whether the light is big enough to render or not.

I just did a test with Full Lighting Evaluation and the problem went away.... but the render times were crazy.

Since I was using BF, presumably adaptive lighting doesn't work, and it reverts to light tree?

[JD3D_CGI]

So, I guess I am goign to have to send this file into you guys.

Just to clarify - I am NOT taking about fireflies, I am talking about entire lights changing their values between frames. See the lanterns in the background.

[vladimir_krastev]

I see, so the lights are not disappearing altogether but changing intensity. This looks like a whole lighting fixture, not a visible VRayLight. Maybe the materials used have something to do with the issue.
Send us the scene for review if you can not manage on your own.

[vladimir_krastev]

This issue is related to VRayLights with very small size and very high intensity. The issue is reported under VMAX-14310.

[garipodelu]

We ran into this issue today. are there any solutions for this?

[JD3D_CGI]

The solution was the make the lights physically bigger so they didn't get winked out in the distance.

[Pixelcon]

I have recently submitted this bug and it is assigned as "Request #345356".
Its status is "Assigned to Development" so presumably it means it will be fixed at some point.

[Morbid Angel]

That's a really old issue in vray and probably other renderers. If light size falls below 1 pixel it will be omitted from sampling. As was pointed out before, increasing the light size will solve the issue. However on scenes where lights are too far to increase the size, only sampling with high min samples will help. But the sampling for min value has to be high like 30-60 or 100 samples.

[Muhammed_Hamed]

I see there is a fix for this issue, a new parameter that could be exposed in the UI of lights SettingsOptions::light_minPixelSize. This makes sure the size of the lights are large enough to be sampled/rendered. We will do more testing then expose this parameter if it helps

Best,
Muhammed

[Muhammed_Hamed]

I can confirm the new parameter fixes the flickering, you don't need to make the lights physically bigger. What DCCs do you guys use?
We will expose this parameter in the UI

Best,
Muhammed

[Pixelcon]

max 24 ..........

[Morbid Angel]

Houdini please And maya.

[Muhammed_Hamed]

max 24 ..........

Thanks!
On the way!

Houdini please And maya.

It is already in Houdini, this is where it was implemented.
Maya will come soon

Best,
Muhammed