flicker on detail animation

[vandy]

Hi, I have a flicker issue with this wheat, which is modeled with very thin triangular strand extrusions. My rendering time for a full frame (1920x1080) is around 53 minutes and I don't want to go much more. Does anybody have any ideas to reduce this? My settings are as follows:
Adaptive DMC 1/4 ns. is .005 with min samples of 16
medium IRmap presets with .2 clr thresh 55/80, detail enhance, 50 radius (precalced IR)
LC; 3000, sample .01, interp 10 (precalced flythru)
Here's the link, sorry it's so short, just a region test of six frames
http://youtu.be/N5t7yjKJPg4
Thanks

[Svetlozar Draganov]

Is it possible to attach the scene , we will try to help you with this flickering.

[vlado]

It would be best if you can get us that part of the scene; in any case, can you tell me how are those thin lines implemented? As a texture or a geometric detail, or something else?

[EDIT] Just saw it's geometry, which means that the flickering is caused by insufficient AA samples - you might have to increase the max. subdivs for the AA image sampler.

Best regards,
Vlado

[super gnu]

id say, even without looking at the scene, the aa settings you are using are the default ones, designed for a fast render. id be very surprised if you could use anything like those settings on an animation with fine geometric detail.

depending on the quality required you might need anything from 2/12 up to 3/25 for your aa settings to fix this. on some scenes where i want a really clean result ive had to go even higher.



id say its useful to raise the min aa samples above 1 ( even if only to 2) since vray has a habit of "missing" details with the min rate at 1.

once youve tried that, id increase the max rate a bit at a time on a -very- small region render of a few frames in a problem area, and play back looped to see the shimmer.


increase until the result is usable.

some things just take a long time to render. this is often unavoidable.


you might find that:


a) there are other areas you can optimise to make up for the gained rendertime. (for a good example, ditch detail enhance and use a more detailed imap instead..
will save you a crapload of rendertime and look just as good, with care. in fact with the medium preset im surprised you can see a difference with it on.- make sure your interp. samples are not too high or the imap will always be blurry)

b) in some cases increasing the aa settings has been known to speed up rendertimes.. you might be lucky.. (its complicated)

[vandy]

To Svetslozar: Thanks for offering to help with the scene, but I did some more testing and I think it's good now.
To Vlado/Super GNU: I changed hsph subd to 70/55 to start with (re-did IRmap), unticked detail enhancement (thought this was necessary with all my detail, but apparantly not), then upped the image sampler in increments until 3/35 seemed good. Thanks guys, it's not perfect, but it's much less noticeable now, AND my rendering times are cut in half without losing any quality I can see. Very important with hundreds of frames to render.