View Full Version : Limiting when volumetric lights are a factor in rendering?

12-22-2011, 06:14 AM
I have a scene with a single volumetric light, which is only active for a short span of frames; for the rest of the animation I have the intensity and opacity key framed completely off.

Nevertheless, when I change the quality of the volumetric light to higher settings, every frame in the animation takes significantly longer to render even though the light shouldn't be a factor in most of the frames.

Is there some way to make the render engine completely ignore the volumetric light except the short span where it's on?

Many thanks in advance!

12-22-2011, 08:19 PM
The crude workaround would be to make a variant of your scene where the volumetric light has been removed. So you'll have one scene to render the frames with the volumetric light and then one scene to render the frames that don't have the volumetric light.

I don't believe there's a way to toggle on/off volumetric lights in the Render Globals panel during render time.

12-22-2011, 10:59 PM
It is interesting. I have seen the same thing with a dome light. If it is in the scene and intensity set to 0, the scene will still render slowly based on the quality settings. I think it has to do with the fact that there is no animation on quality settings or on having the light on and off in a scene. Which is a little strange in a way, but apparently the way it is. You would think that the render engine would know when it has to calculate something and when it doesn't. But apparently when it comes to lights, it doesn't have a way to know this.

12-23-2011, 06:03 AM
Thanks, guys. The "crude workaround" is actually how I'm approaching this for now. It's good to get validation that I'm just not overlooking some arcane trick.

Thanks again! :thumbsup: