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Coherent ratio animation light flickering in volume

Posted: Sat Apr 08, 2017 5:18 pm
by 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.
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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.
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Render settings:
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+ Hot pixel removal = 1 in Camera.

Any ideas? :D

Re: Coherent ratio animation light flickering

Posted: Sat Apr 08, 2017 5:25 pm
by 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.

Re: Coherent ratio animation light flickering

Posted: Sat Apr 08, 2017 6:06 pm
by byMELT
aoktar wrote: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.

Re: Coherent ratio animation light flickering in volume

Posted: Mon Apr 10, 2017 3:48 pm
by 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

Re: Coherent ratio animation light flickering in volume

Posted: Mon Apr 10, 2017 7:50 pm
by 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.