I wonder if this can be done ? IR question

[Oleg_Budeanu]

I wonder if this can be done :
1. render IR and LC in flythrough (camera path) , saving to a file
2. add this IR file with static objects camera movemet to each frame-file of Animation prepass with moving objects.
So in result we will have single frame rendering for each frame but the static part of the scene is calculated in one pass - saving a lot of time.
What do you think about that ?

[super gnu]

issue there is, how does vray know which samples to use from the static map and which to use from the per-frame calculations?

easier option is to use the "use irradiance map" tickbox in the vray material. calculate your flythrough map with all moving objects hidden, unhide moving objects, untick "use irradiance map" in the materials on those moving objects.

unticking this, forces all objects with those materials to use brute force, per frame gi. its important in this case to have the flythrough lightcache loaded as well as the imap when rendering, since the BF calculations for the moving objects will take its sampling from the lightcache on the static environment.

only negative is you dont get gi effects *from* the moving object on the environment, so its only really useful for smaller elements in a scene.

you can fake most of these effects using AO or vray dirtmap to add fake gi shadowing around the moving object.

[Oleg_Budeanu]

Thanks for your explanation , that's a good idea , thought the problem is that i am animating kitchen doors and they are casting shadows to inside. And animation is like door is broken into pieces and they are rotating, so we will get pretty much of the GI change inside. Of course i can take whole part where we need GI change and use it as bruteforce.. Will think about that , thanks ! Before that thought to render as passes - separately flythrough , separately rotating pieces.

[Oleg_Budeanu]

Tried this method now.. Getting weird GI on moving parts. They are definetely rendering with BruteForce though something is wrong https://db.tt/Kr8Meyrf on white panel in the back. It is clearly visible on front panel here : https://db.tt/SkVTeHf3 . These both are GI channels with moving objects and materials with ticked off Irradiance Map. Lightcache and Irradiance map are camera path precalculated and render test was ok at these places.

[AlexP]

Whats preventing you from just brute forcing the whole thing?
Or just using the IR prepass for the whole thing?

It would be a lot less hassle, which or course you pay for with more render time

[Oleg_Budeanu]

Brute force whole thing will take a lot of time to make it noise-free , even with 3.2.
And IR singleframe prepass takes about 1h30m per frame per irradiance map , and plus about 1h20 mins to render. So total 3hr per 1080p frame is pretty much. With flythrough i got about 15 mins flythrough with help of DR render , and about 50 mins per frame , and after that about 30 mins per frame bruteforce + matte objects. Just wondering if there is a way to make it faster.

[AlexP]

1h 30 for 1 frame of IR map seems very very long. May be worth trying to cut that down instead.

[Oleg_Budeanu]

Yeah i agree , though the scene setup itself is like that that it relies a lot on GI , there is almost no direct lighting there, that's why i had to bump up irrmap that high , and i've got a lot of cornices , small details , bevels and etc. Of course that can be faked by AO though the irrmap itself becomes blotchy if i lower it...

[super gnu]

yes with doors opening and changing all the lighting, your only decent option is really bf/LC

swallow the rendertime (rt gpu would be good for this) and get on with it.

the method i outlined is extremely useful for say, people or cars on a masterplan, and similar small moving details.

ive never got a decent result with perframe imap, without cranking the settings so high it takes basically as long as bf/lc, but doesnt look as good.

even your proposed method ( which i cannot see being possible) would not be useful in your case since the opening of the door would affect basically all the gi on every surface..

if thi is not the case ( i.e its a large room and the door opening only noticeably affects the nearby surfaces) then you could look at vrayspherefade, or other comping methods.

[super gnu]

on a related note, a hybrid of your proposal and spherefade might be nice..


an option to set up a flythrough cached gi solution, but have a gizmo with soft edges that allows you to blend from the precaalc solution to perframe bf inside the gizmo.

[Oleg_Budeanu]

yeah well it is always easy just to throw BF\LC - totally agree Though if rendertime is going to 2h with it... it is time to search for another ways.
Currently i am sticking to flythrough of static stuff and bf/lc with mattes. First phase is around 40 minutes per frame , which is not that bad. Second phase will take more or less the same i think.