Hi,
I actually posted this problem a while ago, but then i only had access to the public forum and didn´t get a solution then…
So.
I have a sequence to render with moving camera and moving objects.
I applied my usual workflow:
1.Irradiance map precalculated via backburner with use camera path ticked in Animation (prepass) mode (on “Low” settings).
2. Second GI is Light cache with “use for glossy” and use camera path ticked in single frame mode.
3. After prepass is done, choose the proper IRmap files and switch to Animation (rendering) mode.
I tweaked my settings for the scene according to the great tutorial from Akin Bilgic and while test rendering locally (without animation mode, simple single file per frame), I got rendering times around 10-15 Minutes per frame.
Now in Animation (rendering) mode I´m suddenly haveing rendering times of 3 hours per frame…
It seems to me the renderer is grinding to a halt as soon as any buckets hit a glossy material.
So far I tried switching off secondary GI completely and lowering Interpolation Samples from 20 to 10 or even 5, but neither helped…
I´m at a bit off a loss here, since on some scenes it worked and on others it doesn´t…
Any idea whats happening here?
Actually I switched to brute force+light cache (with use camera path and use for glossy rays ticked) as vlado suggested in my first post about that problem, and render times are back to normal again.
Still no idea why IRmap prepass seems to work at times and doesn´t in other cases…
I keep saying this over and over 
but for moving objects I use bf/lc always. Interpolation methods are great, but not for this. You truly spend more time setting it up and debugging then saving time. I’d rather computer do the work then me
Well, maybe they should change the name of brute force to something that makes it sound like something smart people would use…
I´m kidding, but I´m also serious. Psychology can be a b** sometimes. I usually kept away from brute force, mostly because it really sounds like “if nothing else helps, just use brute force”.
Well, i´ll see how well brute force+LC works in the other scenes of the project.
Since we need it to be at a resolution of 4240x1920 for stereoscopic reasons, keeping render times low is pretty essential…
It used to be called quasi monte carlo, would that be better
Ah, yeah, I vaguely remember, back then I was still a mental ray kid…but that did indeed sound more sophisticated…
This issue might be a bug and it would be very helpful for us if you are able to provide one of those non-working scenes for investigation.
Let us also know which version of Max and Vray are you using.
Thank you very much in advance.
Sorry, probably won´t happen for this project…apart from NDA there are also tons of local assets like proxies, phoenix fluid cache, xrefs etc…
In case brute force+light cache doesn´t work for the other shots and I have to revert back to IRmap+Light Cache, I´ll hopefully won´t run into this issue again, but if anybody else is encountering the problem, feel free to chime in and help with possible bug-fixing…
Thanks for the update.
If you narrow down the issue and reproduce it on a simple scene please send it to us for investigation.