Re: AW: Hair flicker

["Hans Payer" <hanspayer(at)gmail.com>]

I've dealt with a situation like this in the past.  here's the problem I found:

Let's say your scene is saved at frame 1 and that you are rendering on a farm using the skip option (existing frames). All node will load the scene starting at frame one and "internally" refresh every subsequent frames until they find one that hasn't been assign. This scenario should work without problems.  But it you do not use the skip option and point directly to a specific frame( let's say 30), the node with refresh the hair from frame 1 and switch to your frame causing a different result. Try the skip if you can. Or save the scene at the frame you want to render from.

Hans

On 7/30/07, Holger Weiss <holgi(at)mark13.com> wrote:

So, cause i´m not using dynamics, is it better to give the hairs a dynamics,
so it got a cache, and turn all sensitivity to force to zero, that the hairs
got cached ????
And turn this afterwards to read only???

I´ll give this a try if there will be still such pops


Regards

Holger

> Von: Kim Aldis <XSI(at)kim-aldis.co.uk>
> Antworten an: < XSI(at)Softimage.COM>
> Datum: Sat, 28 Jul 2007 08:08:08 +0100
> An: <XSI(at)Softimage.COM>
> Betreff: RE: AW: Hair flicker
>
> Manny¹s probably right, but the steps for rebuilding the cache are very
> specific and need to be followed carefully - . Do this before rendering or
> capture and you should be fine:-
>
>
>
> ·         Set cache mode to read & write
>
> ·         Hit Œreset dynamics¹
>
> ·         Park the timeline right at the end of your animation
>
> ·         Wait for sim to rebuild
>
> ·         Set cache mode to Œread only¹.
>
>
>
> Also, watch for the cache filename. Just like particles, the name is only
> unique within the scene. If you¹ve more than one scene with dynamic hair in
> it you¹ll end up using the same cache for some hair objects. Always rename
> the cache filename to be unique to the scene, preferably when you add
> dynamics.
>
>
>
> Manny¹s also right about avoiding dynamics when you can, not just because
> you don¹t need it. Certainly don¹t rely on collisions working with any
> degree of reliability. If you can get them to work,  be also aware of
> limitations, particularly what happens when hair strands fall either side
> of, say, noses and ears; when it renders the hair will be interpolated
> between the strands and cut through the geometry. Collisions are pretty
> flawed in this respect.
>
>
>
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On Behalf Of
> Kris Rivel
> Sent: 28 July 2007 04:08
> To: XSI(at)Softimage.COM
> Subject: Re: AW: Hair flicker
>
>
>
> XSI's hair caching sucks big time to be honest.  I recently wrapped up a
> project using quite a bit of hair instancing and I had to constantly re-sim
> the hair system to eliminate popping.  There's no guarantee that your sim
> will properly write or be read when rendering so you will often find
> yourself cursing quite loudly and re-simulating on a regular basis.  This is
> one area of XSI thats needs serious improvements.
>
> Kris
>
> On 7/27/07, Manny Papamanos < mpapama(at)softimage.com> wrote:
>
>
>
> I don't think this should be labeled "flicker" since you are getting a
> series of good frames and occasionally there is a bad one.
>
> This is a "pop".
>
>
>
> When you render the bad frames and the same result occurs, I would suspect
> bad "cached" files from dynamics.
>
> Someone may have messed up the cache by opening/playing with the scene and
> the cache was not set to "read only"
>
> Or a computer can simply not access the cache.
>
>
>
> To fix, you may need to:
>
>
>
> Backup and remove the cached files
>
> recreate the cache,
>
> Make sure the path is accessible to all computers on the farm.
>
> Render the popped frames.
>
> I personally would avoid using dynamics on Hair since it's not really
> necessary here.
>
>
>
>
>
> Manny Papamanos
>
> XSI SPECIALIST AT SOFTIMAGE HEADQUARTERS
>
>
>
>
>
>
>
>   _____
>
> From: owner-xsi(at)Softimage.COM [mailto: <mailto:owner-xsi(at)Softimage.COM>
> owner-xsi(at)Softimage.COM] On Behalf Of Wayne Williams
> Sent: Friday, July 27, 2007 12:02 PM
> To: XSI(at)Softimage.COM
> Subject: Re: AW: Hair flicker
>
>
>
> The max is 14 ya?
>
> ----- Original Message -----
>
> From: FLINX(at)mark13
>
> To: XSI(at)Softimage.COM
>
> Sent: Friday, July 27, 2007 11:36 AM
>
> Subject: AW: AW: Hair flicker
>
>
>
> ok...i'll try that....the segments are up to 10 now....what would you
> recommend?
>
>
>
>
>
>
>
>
>
>
>   _____
>
>
> Von: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] Im Auftrag von
> briand(at)hatchling.com
> Gesendet: Freitag, 27. Juli 2007 15:59
> An: XSI(at)Softimage.COM
> Betreff: re: AW: Hair flicker
>
> We had something pretty similar happen to us. What seemed to work was upping
> the # of segments on the hair.
>
>
>   _____
>
>
> From: "FLINX(at)mark13" < flinx(at)mark13.com>
> Sent: Friday, July 27, 2007 6:13 AM
> To: XSI(at)Softimage.COM
> Subject: AW: Hair flicker
>
>
>
> ehhhmmmmm...holger that's not 100% correct...we had to rerender,
> because ONE machine already messed up every 10th (or so) frame.
>
> so we wanted to rerender on a machine that didn't produce bad results in the
> first render....but now those frames are fuckedup aswell....
>
> here's a short movie: www.mark13.com/goto/flinxes
>
>
> thanks for suggestions folks...
>
>
>
>
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: owner-xsi(at)Softimage.COM [ <mailto: owner-xsi(at)Softimage.COM>
> mailto:owner-xsi(at)Softimage.COM] Im Auftrag von Holger Weiss
> Gesendet: Freitag, 27. Juli 2007 11:58
> An: XSI(at)Softimage.COM
> Betreff: Hair flicker
>
> Hi,
> We have a bizzar problem with rendering hairs We open a scene with a hairy
> charakter and render it on different computers.
> All is good and no flicker occures.
> But than we have to do some rerenderings ( on one computer a day later) and
> the hairs behave totally different .
>
> Had anybody same problem and a quite good solution???
>
> Regards
> Holger
>
>
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