Rendering an Animation with Moving Objects

[DanielWichterich]

In the new help files i found the following "This tutorial focuses on the irradiance map to gain some speed. If you can afford longer render times, using a simpler approach like Brute force GI for primary rays, and Light cache for secondary rays might prove less complicated and faster to set up."

I now do wonder, in that case how is the lightcache set up? When set to single frame, doesn't that lead to flickering during the animation?

[joconnell]

Yes, there might be flickering but that's the nice thing about having a separate primary and secondary bounce of global illumination. The very first bounce can be direct lighting hitting very sharp surfaces so can have some very detailed areas, almost caustic like in their look at corners for example. The secondary bounce however is a bounce of a bounce, and from this one on, there's little or no sharp detail, it's all just big washes of soft light so a very smooth solution is preferable. In the case of light cache, it'll give you this pretty quick and you can use pre and post filtering to try and remove any flickering. The nice thing is you can also set up a render using light cache for primary and secondary bounces which is pretty quicker per frame and set off a section of your animation to see how flickery it is. You can tweak the LC settings without taking the hit of a better primary bounce solution and once you're happy that it's stable, switch back to something like brute for your primary bounce.

[svetlozar.draganov]

All adaptive Global Illumination (IM/LC) solutions produce flickering in animations with moving objects. However in certain scenarios like interior-animations generating noiseless frames with Brute Force could take a tremendous render-times and in that case it is worth to use Light Cache as a secondary bounce engine since it could trace much more paths than Brute Force providing smoother GI solution.
The amount of flickering is directly related to the LC settings - if you have some just increase LC settings until it becomes indistinguishable. A few things that might help for a better LC solution:

* Use light cache for glossy rays - turn this off if you have flickering into glossy-rays like glossy reflections and etc.
* Retrace threshold - turn on this option if you have flickering in high-frequency details / light-leaks / blotchiness into glossy-reflections

[DanielWichterich]

Thanks a lot, both of you!