Gi issues....please help!!

[Smalerbi]

Hello all,

I sure could use some help with this problem. I have been spending the past 3 days trying to wrap my head around this and now I’m to the point where I just want to go quietly off to some corner of the house and open up a major artery. I posted this problem in the general section of the forum with no luck so I’m hoping I will get a fresh set of eyes on this.

Here is the problem. I have one camera pass consisting of 1800 frames. In the scene, there will be several moving objects, primarily cars and people and of course the camera will be moving as well. See below for the following methods and results.

Method 1:
Med. Animation presets, IR first bounce (Incremental add to current map) and LC second bounce (Fly through). Rendered each frame and yes it took forever to render 1800 IR passes with one machine. Somewhere the IR map got corrupted and that was a bust.

Method 2:
Med Animation presets, Mode – Animation (pre-pass). This is the first time using this setting. LC second bounce (Fly through). Rendered the Animation pre-pass maps over 5 machines and ended up with 1800 IR maps. I then loaded the first pre-pass map and the LC map in there perspective places and rendered the scene. Please see link below. There is GI noise especially in the shaded areas. Look at the plants. I tried different Interp frames setting and ended up with the same results.

http://www.drealm.net/Projects/Vray/GI-Test.mp4


Method 3:
Using Brut Force for the first bounce and none for second. Regardless how high I made the subdivision settings, I still ended up with GI noise in the final image animation.

Method 4:
Rendered IR maps over 5 machines but in groups. For example….machine 1, frames 0-300, machine 2, 300-600…etc. Ended up with 5 groups of IR maps. Then merged them together using the IR viewer. I ended up with a 1.8 gig IR map. Tried to render the scene but It froze up at the LC filtering stage. Another bust.

I know there are people out there that are a hell of a lot smarter then me so if you could please shed some light on this subject….I would greatly appreciate it.

Thanks in advance,

Scott.

[olika]

Hi,

i guess it has something to do with the fine detailed geometry at the plants.

To reduce flickering every "lightray" should hit the supposed position as accurate as he could from calculation to calculation or frame by frame. And then also for indirect light bounces.
Between all those little leaves it is really hard to calculate it correctly. As you said even a bruteforce method isn`t able to solve it because it`s also not accurate enough.

I would try to play around with the vray- and objectproperties of those plants. Turn off Gi / Recieve GI / Generate GI , just try to exlude the from your GI Calculation.
You can also then light them seperatly with the exclude option in your lights and just light them with a fake GI lighting ( 1 or 2 omnis ).
If everything fails then you can last but not least try to split the whole thing in different rendering passes.

hhmm ... as i watched the video again now ( which is a little low res to figure out whats bad in the inc. add to current map mode ) i`m not sure if it could also be a sampling issue.
I mean, first you have to figure out what`s responsible for the flickering. Is it Gi or sampling, glossy reflections etc.
Are those materials a little bit more complex for example: are they transparent or two sided materials or glossy reflections. If it`s the case then you could consider to simplify/optimize your materials for the plants,
cause at one point the leaves are very far away and you won`t see to much details of them and another point is that you can /reduce/avoid sampling noise on those little details and save some renderpower for other parts.
But i`m pretty sure that on the left video (animation preset) it`a GI Issue.

Hope i could help you a little bit.

Grüße Oli