I’m working on an animation of a small apartment building in which I am looking down into the second floor to see the layout. Midway through the animation I want to fade in the top floor which has a terrace. What would be the best way to calculate the irradiance map? I tried doing a MULTIFRAME INCREMENTAL but as soon as vray hits the first frame that starts changing transparency, it freezes. Should I render the first half and second half separately with MULTIFRAME INCREMENTAL and then render separately the (40) frames that have the change of transparency calculating the irradiance map for each frame using SINGLE FRAME or BUCKET MODE? Doing this, won’t I see a difference in the quality of the lighting in the animation?
no
render a sequence prefaded, render a sequence postfade, make sure you have them both rendered for where you want the fade to happen
then, use a post-editing program like combustion, premiere, or any of the free ones to fade between the two clips - you’ll save yourself a lot of headaches
Great…I’ll do it in Premiere. I thought about that earlier, but wanted to try and resolve everything in VRay just for the experience sake…but you are right…this way it will be much easier!
i also use this method.
its not much slower since vray has problems with objects that have visibility less than 1. (at least in builds available to me)
Its not just Vray… scanline gets really slow as well
Compositing is the best way to do this - many transparent objects cause a lot of extra rays flying around; further on you will be able to see inside of walls and floors etc, which is probably not exactly what you need.
Best regards,
Vlado
Its definately easier and faster to do fades like that in post, also if you need to change the rate that the object fades it takes seconds to chance rather than hours for a rerender.
-dave
and for all those who complain they dont have compositing or video editing packages. max has video post which works well for what it is.
Or you can go to Sony Media Software and buy Vegas movie studio ($89.95us to $129.95us) for light basic video editing or Sony Vegas 6 ($449.96us to $674.96us) which is what Ive been using for years and its faster, cheeper and will do pretty much anything and everything that Premiere will do.
BTW the main big differences between Vegas and Vegas movie studio is vegas has unlimited A/V tracks and Movie studio has 4 A/V tracks which there is a comparision chart here
-dave
thanks for the info dave, what are the codecs like that come with it?
I had a little dabble with the sony vegas software awhile back.
Great program 
doesnt suprise me you had a dabble da force…
well vegas comes with a few codecs and will also use most of whats installed on your system. Also it has a network rendering option but I havnt tried it yet. Anyway see below for a screen shot of my vegas6 codecs…
-dave
thanks dave, migth have to look into this, im sick of the crap that premiere produces
yea when I was in the market I tried both Premiere and Vegas and besides stability and ease of use I hated the fact I had prerender my preview to see the changes I was making in the video. Where as with vegas I drop the clips in to the tracks, arange them and hit play, just that easy 
-dave
famous last words…
was that the old or new premiere? i think the two editors i had the most joy with would be IMC Incite and DPS quatro