Flickering / Shimmering trees in animation

[Saulman]

Hello,

Please can someone help me out? I've been working on an animation for a development in Cape Verde. Please could someone take a look at the attached link and explain why the trees are flickering or shimmering in this way? http://www.mesh-media.co.uk/vray/CV-Test.mpg

I have used a renderfarm with the light cache and irradiance map set from file. The files were created with the light cache set to flythrough and the irradiance map set to incremental add to map. Both files were calculated on a single machine.

Here are the settings at the time of render........



The trees are xfrog but have been retextured so they don't have any reflection or refraction to speed up the render times.

Any help would be very greatly appreciated.

Thanks

[Deflaminis]

This thread might help. http://www.chaosgroup.com/forums/vbu...ght=shimmer%27

[gkolln]

Hi, We do allot of architectural masterplan work and find this problem is normally due to the sampling of fine geometry.

Are you using DMC and if so what are your settings?

Also it looks like you have some co-incident geometry in your pool that is also causing some flicker.

[johnszot]

welcome to hell, saulman.

the flicker thing is a real pain - in your case i also believe yr barking up the wrong tree - looks to me like AA probs and not GI issues.

i'm betting yr using DMC and something similar to the universal settings - our solution has been to bite the Adaptive subdivision bullet and use a high range like 1/4 to get rid of the artifacts yr showing. but render times go up pretty quickly. for slow shots like yours with so much detail, i don't think there's much option for you.

of course, i'm speaking from a relatively modest position of techincal achievement - i'm hoping some of the heavy-weights will weigh in here. there was an animation posted recently of a wetlands project that had excellent AA quality with a ton of vegetation.....lemme go find the thread....

[johnszot]

here 'tis:

http://www.chaosgroup.com/forums/vbu...agune-of-Nador

check his trees out - very nice....and no motion blur....

[MHolmstrom]

I noticed you have "Check sample visibility" checked. Have you tried to render without it?
For this kind of scene, I think it might be even detrimental, since VRay won't use and interpolate the IRmap samples which are behind leaves.
Your LC samples seem kinda overkill too. Exterior scenes don't usually require as many bounces as interior.

I'd try to get a low-detail, flicker-free GI first, then use Detail enhancement or ambient occlusion on top of that instead of calculating a high-res irradiance map to handle everything.

[trick]

Even with the lowest GI settings (but loading from stored files) you can have flicker-free trees if you set AA min value 2 or 3 or higher !!!!!
If you set min value to 1 it means that tiny details are 'seen' in one frame and 'invisible' in the next. So you need to sample subpixel to make these tiny details visible - preferrably - ALL the time !!!
Low GI settings may give you horrible lighting and even no lighting on certain tiny details, but once calculated and loaded from file these should not make your trees flicker !!!!!!!