Coherent ratio animation light flickering in volume

[byMELT]

Hey guys!

We're finalizing one scene setup - it's a behemoth one-take, 2.5 min. VR experience, 3 months of work until now and onoy 10 days to go with rendering 4050 frames. That's why we're optimizing all we can. Right now I found coherent ratio = 1 to work wonders with everything but one, very important light. I'm showing you guys all the info and hope someone can help, because the schedule's tight!


Here's the animation test - in front of us there's blue light that flickers in volume fog:
http://vimeo.com/212389924/5f27978db6 (forum's vimeo embed doesn't work with private video)

Here's the comparison beetween coherent ratio 0 and 1. 1 works fine everywhere in the scene aside the blue light flicker.


Light setup. There are two lights: 1 only to look at with no illumination, and one non-visible that's lighting much of the scene's mood.


Render settings:



+ Hot pixel removal = 1 in Camera.

Any ideas?

[aoktar]

coherent_ratio=1 is worst idea i think. keep it low as possible or off. And try to optimise your performance with light samples.

[byMELT]

coherent_ratio=1 is worst idea i think. keep it low as possible or off. And try to optimise your performance with light samples.

I thought so and never even raised it above 0, but it works wonders in this scene, aside that one light and only in volume fog.

[bepeg4d]

Hi byMELT,
I have never set it more than 0.75, but with more sampling than yours. Try with 0.5, it should be enough in your case.
ciao beppe

[mbetke]

I used it with animations and got flckering as well. So you have to put in more samples or reduce the coherent value. For most stills I use coherent= 1 and it clears out nice.