Radiosity - how to avoid flickering in animation?

[Tomas]

Hi all,

I'm sorry if this is a dumb question, seems pretty basic to me, but I tried searching and couldn't find any reasonable solution or workaround.

I get some nasty flickering in animation when I use the default Radiosity settings in C3D. Please have a look at an example in the video under the link below.

Animation flickering:

Radiosity settings:

I understand the flicker in "shadow" areas is caused by the Irradiance Cache settings. By trial and error, I figured out that when I change the Error to 0.0 and Rmin to 0.0, the animation looks perfect, but the render time is 10-15 times longer

Is there something else I could do to prevent the flicker without impacting the render times too much?

Thank you

 

[misoversaturated]

Is there something else I could do to prevent the flicker without impacting the render times too much?

Not really I'm afraid.
With Rmin at 0 and Error at 0.15 the number of samples would drive the noise, you can try 200, 400, 800 etc samples until the flicker is gone and get away with less than 10x render time.

 

[Tomas]

Not really I'm afraid.
With Rmin at 0 and Error at 0.15 the number of samples would drive the noise, you can try 200, 400, 800 etc samples until the flicker is gone and get away with less than 10x render time.

Thank you for the advice. Certainly worth testing out, I haven't thought of that.

 

[frank beckmann]

Nothing beats AO rendering in terms of speed for stills.
For animation "Detail detection" along more samples will help.
But I´d go with a dedicated light source: large area light with 6 samples for instance:

Cheers
Frank

 

[Tomas]

Nothing beats AO rendering in terms of speed for stills.
For animation "Detail detection" along more samples will help.
But I´d go with a dedicated light source: large area light with 6 samples for instance:

Cheers
Frank

Great tip Frank! A combination of 1 Ambient and 1 Area light seems to do the job nicely for me and rendering time is the same as with the Ambient Occlusion at default settings

 

[Tomas]

Thank you both for your advice.

Ramping up the samples to 600 and leaving the Error settings at 0.15 worked ok. The render time is approx 50% longer than default settings with 100 samples, which is much better than 1000% increase by changing Error to 0.0. If some noise was noticeable, it could be fixed in postproduction by adding some anti-noise effect/plug-in.

Turning off the Radiosity completely and adding Area light instead required a bit of playing around to get the lighting just right, but in the end, it looks almost itentical as AO and the rendering time is roughly the same. No flicker. Thank you for this amazing trick Frank