CGTalk - Fur flickering, smooth uv´s on workaround

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JWRodegher

12-01-2006, 08:40 PM

I have been going through some real problem working with fur. Actually, the help file in maya mention a solution for the problem, but it is actually at the cost of the look of it. Let me explain. It´s sort of known already than when you apply fur on model with the polysmooth node, and the smooth uv´s turned on, you get flickering all over the surface. The help file says that the work around for this is obviusly turn the smooth uv´s off. But, then, you get a difference in the look of the hair. In this particular case, I was using fur for the eyebraws. I know, theres other ways to make eyebraws but I like the ones I did with fur, and I also get rid of the rigging problem I would have if I use sprites or something like it. Well, thing is that the uv smoothed model with fur (wether it´s a proxy or the low version smoothed) looks like this:

http://cablemodem.fibertel.com.ar/jonnhy/newmode33.jpg

Which is fine. Or at least is acting the way it should. Bending the right way and smoothly.
Problem comes as soon as I wanna render an anymation with it. I get the flickering of course. Now, if I apply the solution help file sugests, I get this:

http://cablemodem.fibertel.com.ar/jonnhy/newmode32.jpg

The eyebraws look kinda messy, and they dont bend right. Its not THAT big difference,
but in the overall look I think its kinda awfull. So, what would be the solution for this?
I came up with a workaround, I´ll share right now. This thread´s idea is to share ways
to solve this (if there´s any other as I hope there is cause mine isn´t a very smooth one).

After tryin´several things like, the low rigged geo wrapping the high res (which didn´t work as it didn´t wrapped smoothly and it makes my riggin way heavyer), making an instanced
duplicated from the smooth proxy or the polysmoothed low geo (it still have a smooth uv´s
which is the devil here), and such I though of what would happen if I just cached the geo
from the high res and apply the fur to it. That was pretty magic actually.

So what I have is, my low rigged model in a layer, a high res model in another layer
(which is just a smoothproxy with smooth uv´s ON - that´s important); So all you
have to do is, duplicate the smoothed proxy one (and instance duplicate actually) and
at last, you just make a cache of the geometry along the animation (which means all this
goes right before rendering). Then you apply the fur to it, with all it´s maps (in my case,
I got polar, balldness, equalizer and lenght). That´s it. Flicker free smoothed uv´s fur applyed.

Unfortunately, cache geometry is a Maya 8 feature. So this workaround will be usefull only
if you have Maya 8. I hope it helps in case somebody was looking for a solution to this and
feel free to suggest any othey ways to work this out. Sorry for the long post and the high res
images (I sort of need to show the detail).

Cheers!

yenvalmar

12-08-2006, 07:43 AM

and probably SHOULD :) render the fur in passes, with the geo at the correct smoothing to make it look correct, then the geo smoothed, and composite... i always wind up compositing fur anyways.

Dustin

12-08-2006, 08:30 AM

I might be missing something here, but isn't the reason the UVs flicker because of the smooth node? So couldn't you just delete non-deformer history?

I am still a noob with this fur stuff, so I haven't actually tested this out yet. But thought I would throw that out there.

JWRodegher

12-09-2006, 01:35 AM

Well, I have tryed to render a pass and compose it, but for some reason I didn´t get the same results. The mask didn´t look good, anyway, It was only one shot and I thinkg I´ll give it a try again, cause I like to being able to composite everything. Thing is, that having a render pass for the fur only doesnt solve the flickering caused by the smooth uvs (in either smooth or smoothproxy). I mean, you still need a smoothed uv version on a surface withouth the smooth uvs node.

Dustin, I believe that was the very first thing I tried, and it didn´t work. I dont remember that well, so I might try it again. Even though, the idea, is not loosing your low res geometry, I´ll still need to animate. If I delete non deformer history, only a high res version will remain.

Thank you very much both for the suggestions. :D Cheers!

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