Major Light Flickering on Animation

[adamFFKR]

We are trying to do this fairly simple animation and we keep getting big blotches of light flickering on and off. I am posting our settings here, but we have tried many other settings as well with no success. We have tried with very high settings on irradiance map and the problem persists even though render times go through the roof.

Sorry for the low quality video, but it should be sufficient to see the problem. It is very evident on the side of the MRI bed at one point, and also in the last room behind the cabinet.

http://www.youtube.com/watch?v=qkIEc8U0_cY

[jacksc02]

it just looks like bad GI.
When you are calculating the GI what are you using for your secondary bounces?

[vlado]

The max. rate for the irradiance map is too low for this animation. You are using the "Use camera path" option and the irradiance samples for a single frame are spread over the entire camera path; since the camera moves over a relatively large distance, the samples are spread quite far apart.

To avoid the issue, try using 0 or 1 as the max. rate for the irradiance map; you can also try with the "Use camera path" option off.

Best regards,
Vlado

[adamFFKR]

Yes...we figured all along that it is a problem with GI, but have been unable to pinpoint what setting we are getting wrong. We are using irradiance map with light cache.

We will try what vlado suggested and see how it goes.

[adamFFKR]

Vlado,
One question though. Do we set the Max rate to 0 or 1 during the "animation prepass" set up or the "animation rendering" set up. Thank you for your help.

[vlado]

You need this for the "animation prepass" phase, which is when the irradiance map is calculated.

Best regards,
Vlado

[adamFFKR]

Thanks for the reply. I tried doing as you suggested changing the max rate to 1 and turning off the use camera path option. I've attached a jpeg of my prepass settings. Our machines are dual xeon 2.5 GHz with 8 GB ram, and the scene is 2.1 million polys. I'm getting irradiance map calculation times of 39 minutes per frame. Does this seem correct in anyone's opinion? The few frames that I actually final rendered were roughly 18 minutes each. I'm looking at appx an hour per frame at 720 X 486. 1200 frames total. Any thoughts?

[vlado]

How long does the light cache take to calculate? I see you are not using the "Store direct light" option for the light cache - if you turn it on, you might be able to speed the irradiance map calculations.

Best regards,
Vlado

[adamFFKR]

Lightcache is taking roughly 3 minutes. I'll try turning that on and see if it speeds things along abit. I compiled the frames that i did render together, and from what I can tell, it seems to be working. I'm still getting some flicker, but it appears to be just reflection on some of the highly reflective metals. Would I increase the reflection subdivisions in the material to get that to stop flickering? I truly appreciate your help Vlado and others. Thank you.