CGTalk - Hair prerendertime

pauldryzen

09-05-2003, 05:19 PM

Hi,

I have a question about the prerender calculation for hairs in XSI.

The scene I'm actually working on is quite simple, it is a medium resolution cow modell, which has to look like a real cow (no close-up needed).

The settings for the hair are:

20.000 hairs
geometry shader
Strand multiplier: 50
hair segments 5

NO dynamics!!!

The rendertime is not to high, about 3 minutes per frame. Only the preprocessingtime for each frame is extremely high (4 - 15+ minutes, depending on how many hairs I render).

Would be really nice if someone could tell me if this is normal or when not, what am I doing wrong?

Thanks Paul

sean_G

09-05-2003, 05:34 PM

im just going to hazzard a guess here and say that somehow your BSP settings for the hair renderer got altered accidentily.
try cmparing your settings in the hair's property dialougue with default settings... good luck

tachy0n

09-05-2003, 06:00 PM

At those settings, you are rendering close to a million hairs, each of which has to be first converted to a MR hair primitive curve by XSI. So you are going to get high pre-render times, no matter what...

pauldryzen

09-08-2003, 09:23 AM

@sean_G:

The bsp settings are not modified. And the rendering is quite short, only 3 min per frame.

@tachy0n:

Sounds interesting, any Idea how to speed up the prerender time?

Thanks

Paul

tachy0n

09-08-2003, 11:48 AM

I don't think there is any way to speed it up short of reducing the settings themselves. You could reduce the multiplier, but then the quality and density of har will suffer. What we really need is a way to render short hair without generating curves. Or at least some way to cache the hair to disk so that they don't have to be generated every freaking time.

Also you can take a look at the 2d_fur output shader that comes with XSI, but it is hard to control, and doesn't always produce nice results.

pauldryzen

09-08-2003, 12:24 PM

shit,

maybe I can tell my boss that it would be a good idea to use Maya fur for this project...

thanks for the help

StefanA

09-08-2003, 05:50 PM

You should e-mail questions like this to the XSI e-mail list where you can get a lot of answers from users who renders hair a lot.

Subscribe here:
http://www.highend3d.com/xsi/listserver/

The XSI list is by FAR the best resource for xsi.

Despite that cgtalk might be a good forum, the XSIbase.com has more to offer for xsi users. You could also try there, but my best bet for getting good help would be the xsi list.

best regards

.stefan andersson

pauldryzen

09-08-2003, 07:53 PM

Hi StefanA,

I´ve asked the same question on xsibase.com, but the listserver is a good idea.

Paul

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