POV-Ray : Newsgroups : povray.binaries.animations : Hair test (WIP, MPEG1 352kb) Server Time
5 Jul 2024 09:25:34 EDT (-0400)
  Hair test (WIP, MPEG1 352kb) (Message 1 to 10 of 10)  
From: Tim Nikias
Subject: Hair test (WIP, MPEG1 352kb)
Date: 25 Jan 2005 18:11:36
Message: <41f6d228@news.povray.org>
So, I'm currently doing some tests on how to efficiently simulate a single
hair using a normal in which it starts, gravity, and wind. As of yet, few
parameters control the effect of gravity and of wind, but some tests have
showed that the length between nodes affects the outcome somewhat, which is
something I'll be investigating. I'm also thinking about limited
vector-fields and such to model the hair, but, like I said, everything's
just in an experimentation phase. Just wanted to show off what I'm currently
working on.

This test animation shows several strands of hair. The red cone in the top
corner shows the direction of the wind. The hairs get weaker during the
animation, but not very much. If you cycle it, you'll notice a rather small
jump at the end of the animation, that's when the hairs suddenly get stiffer
again.

I satisfied with the visual look, but want to do some more testing,
especially on how to achieve adaptive length-seeking without losing
detail... Anyways, suggestions, comments and links to well-documented hair
implementations based on techniques I could actually implement within
POV-Ray are welcome! :-)

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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Attachments:
Download 'hairy.mpg' (353 KB)

From: Stephen McAvoy
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 25 Jan 2005 19:01:17
Message: <kcndv0lqb2taslqt9h2npq9secsp1eu9gt@4ax.com>
On Wed, 26 Jan 2005 00:10:23 +0100, "Tim Nikias"
<JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:

>Regards,
>Tim

I don't know why but it made me laugh.

A worthwhile project.

Regards
        Stephen


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From: Rune
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 26 Jan 2005 18:09:06
Message: <41f82312@news.povray.org>
Looks very interesting. :)

How does this animation work with regard to the set of basic hairs? Is the 
set the same in every frame, or is a new set generated for every frame?

Do you think that gravity and wind affects hair in very different ways, or 
would it perhaps be possible to cheat and just use a single combined force 
vector that simulates gravity and wind at the same time?

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk


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From: Tim Nikias
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 27 Jan 2005 01:13:05
Message: <41f88671$1@news.povray.org>
> I don't know why but it made me laugh.

Always a good think to get people to laugh (even if it wasn't the
intention...)! :-)

> A worthwhile project.

Thanks!

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Tim Nikias
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 27 Jan 2005 01:20:12
Message: <41f8881c@news.povray.org>
> Looks very interesting. :)

Yup, thought so myself...

> How does this animation work with regard to the set of basic hairs? Is the
> set the same in every frame, or is a new set generated for every frame?

A new set for every frame. Because gravity always works downwards and the
wind doesn't, I have to recalculate the set, or the hairs will suddenly have
a different direction in which gravity pulls them.

> Do you think that gravity and wind affects hair in very different ways, or
> would it perhaps be possible to cheat and just use a single combined force
> vector that simulates gravity and wind at the same time?

If I'd actually simulate the hairs using springs or such, I would just pop
gravity and wind as a force onto the spring's joints and that'd be it. What
I'm doing though is to cut the hair into little parts and bend each on
slightly downward, no matter where it is pointing to, using vaxis_rotate
with an axis calculated by the cross-product of gravity-direction and
current hair-normal. This it is more straightforward and can be calculated
in one go without having to simulate several springs, whilst retaining the
same length for every section and thus the whole hair.
Wind is just added in an interpolated fashion: keep much of the original
direction of a section and add little wind, closer to the tip, there's more
wind added and less direction kept. To ensure the proper length I normalize
the sum and multiply it with the section's length.
The stiffness of the hair can thus be controlled with a value which limits
the angle between the original hair-direction and the new one when bending
it downward for gravity, and a parameter to modify the wind-addition.

I am thinking about scripting a real simulated hair though, for animation
projects.

Regards,
Tim

Offtopic- PS: I'll be running away from the clone in a few hours... :-)

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: Stephen McAvoy
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 27 Jan 2005 02:14:08
Message: <d45hv09qm287hiuhll1b7am5farn39157e@4ax.com>
On Thu, 27 Jan 2005 07:12:36 +0100, "Tim Nikias"
<JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:

>> I don't know why but it made me laugh.
>
>Always a good think to get people to laugh (even if it wasn't the
>intention...)! :-)
>
It tickles my fancy, I think it's cute.

Regards
        Stephen


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From: Dan Byers
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 27 Jan 2005 13:05:00
Message: <web.41f92c8a270b5b2c5e9020690@news.povray.org>
Reminds me of a sea anenome from "Finding Nemo", only upside down. :)

--------------------
Dan
Goofy Graffix - http://www.huntel.net/goofygraffix


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From: Tim Nikias
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 27 Jan 2005 15:47:28
Message: <41f95360$2@news.povray.org>
> Reminds me of a sea anenome from "Finding Nemo", only upside down. :)

Ooooh, good idea! (writes a mental note for a future image...)

Oh, and thanks for comparing it to such a high-quality movie! :-)

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: SJH
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 28 Feb 2005 01:40:00
Message: <web.4222bb91270b5b2c1437928d0@news.povray.org>
"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> So, I'm currently doing some tests on how to efficiently simulate a single
> hair using a normal in which it starts, gravity, and wind. As of yet, few
> parameters control the effect of gravity and of wind, but some tests have
> showed that the length between nodes affects the outcome somewhat, which is
> something I'll be investigating. I'm also thinking about limited
> vector-fields and such to model the hair, but, like I said, everything's
> just in an experimentation phase. Just wanted to show off what I'm currently
> working on.
>

Tim, are you still working on this?  I played with hair about a year ago.
You can see one of my old movies at http://hansel.pinerypointe.net/hair.avi

One thing you'll find is things get more complicated when you put a head in
the middle.  Then you have to have some sort of force that keeps the hair
from going inside the head.

At one time I rendered a movie like this with .001 inch hairs and about a
million of them. It took a long time but it looked pretty convincing.


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From: Tim Nikias
Subject: Re: Hair test (WIP, MPEG1 352kb)
Date: 28 Feb 2005 04:51:09
Message: <4222e98d$1@news.povray.org>
> Tim, are you still working on this?  I played with hair about a year ago.
> You can see one of my old movies at
http://hansel.pinerypointe.net/hair.avi

Nice one! No, I've stopped working on them, as their purpose was to simply
cover an object with hair/fur, not animate it. Additionally, like you said,
rendering and simulating thousands of hairs will get very parsing intensive,
which in most cases will just take too long to be a consideration unless
you've got several PCs behind your back and the time to let them crunch on
the job.

The macros to do this can be found on my website, they're the Surcoat Macros
to sample and object, and the Surcoat2Hair macro, which take the samples and
"hair" them.

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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