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From:
Subject: question concernig uv_ mapping
Date: 28 Apr 2004 10:18:39
Message: <408fbd3f$1@news.povray.org>
Hello (sorry for my english, I'm french :-p),

I'm working on POVRAY for few time, and there is something I'm not able to
obtain: I have a very complex object, made on a CAD program (Pro Engineer),
and I'd like to apply a carbon texture on it with a realistic render.I have
followed the tutorial of Oxonale :
http://www.oyonale.com/ressources/english/tutuv.htm , a very good tutorial
but I have still a problem: I can't save a constant scale of the texture on
each triangles because they are very deformed on the uv_map. So the result
is that I have a variable weaving of my carbon on the surface... It's not
very realistic. Does anyone have a solution? Thanks a lot.


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From: Gilles Tran
Subject: Re: question concernig uv_ mapping
Date: 28 Apr 2004 18:13:43
Message: <40902c97@news.povray.org>

news:408fbd3f$1@news.povray.org...
> http://www.oyonale.com/ressources/english/tutuv.htm , a very good tutorial
> but I have still a problem: I can't save a constant scale of the texture
on
> each triangles because they are very deformed on the uv_map. So the result
> is that I have a variable weaving of my carbon on the surface... It's not
> very realistic. Does anyone have a solution? Thanks a lot.

In fact I'm supposed to have removed this tutorial from the site because
it's not very up-to-date...
In any case, the problem of creating uniform-looking uv maps is a difficult
one and there's no general, easy solution for shapes other than simple
primitives like spheres, cubes or cylinders. Creating good uv maps requires
a good uv mapping utility that can make a default projection and then lets
you move the vertices to fix the problems. UV Mapper Classic and Pro are
good starting points, and then the prices start climbing quickly with apps
like BodyPaint or Deep Paint... And even with those uv mapping isn't a piece
of cake: texturing a complex model can take hours, or days. Even in
movie-quality CG one can spot some uv stretching issues when characters move
(joint areas for instance).
If you have a very complex model you'd better texture the different parts
separately, trying to use the simplest projection for each part. You'll have
also better control on the relative scale of the textures between parts (a
common issue for multi-part models that are already uv-mapped).
Now, not all textures require uv-mapping and many times one can get away
with traditional  procedural mapping. What is a "carbon texture" exactly?

G.

-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters


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From: Christopher James Huff
Subject: Re: question concernig uv_ mapping
Date: 28 Apr 2004 19:19:58
Message: <cjameshuff-0596FF.19185928042004@news.povray.org>
In article <40902c97@news.povray.org>,
 "Gilles Tran" <gitran_nospam_@wanadoo.fr> wrote:

> Now, not all textures require uv-mapping and many times one can get away
> with traditional  procedural mapping. What is a "carbon texture" exactly?

I'm guessing he's talking about a carbon fiber cloth composite. The 
weave of the cloth is getting distorted by the UV mapping.
Here's some good carbon cloth pictures:
http://www.stickerpimp.com/projectmazda/dash/airbag/

It would be a challenge to create a good texture for this...it is very 
view-dependent, so a simple image_map clearly won't give a very 
realistic result.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/


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From:
Subject: Re: question concernig uv_ mapping
Date: 29 Apr 2004 04:21:45
Message: <4090bb19$1@news.povray.org>
OK Gilles, thanks for your answer... I thought it wouldn't be so easy :-(
I'll try to divide my part into smaller and simplier ones, and apply
"classic" image_map...

Herve


news:40902c97@news.povray.org...

> news:408fbd3f$1@news.povray.org...
> > http://www.oyonale.com/ressources/english/tutuv.htm , a very good
tutorial
> > but I have still a problem: I can't save a constant scale of the texture
> on
> > each triangles because they are very deformed on the uv_map. So the
result
> > is that I have a variable weaving of my carbon on the surface... It's
not
> > very realistic. Does anyone have a solution? Thanks a lot.
>
> In fact I'm supposed to have removed this tutorial from the site because
> it's not very up-to-date...
> In any case, the problem of creating uniform-looking uv maps is a
difficult
> one and there's no general, easy solution for shapes other than simple
> primitives like spheres, cubes or cylinders. Creating good uv maps
requires
> a good uv mapping utility that can make a default projection and then lets
> you move the vertices to fix the problems. UV Mapper Classic and Pro are
> good starting points, and then the prices start climbing quickly with apps
> like BodyPaint or Deep Paint... And even with those uv mapping isn't a
piece
> of cake: texturing a complex model can take hours, or days. Even in
> movie-quality CG one can spot some uv stretching issues when characters
move
> (joint areas for instance).
> If you have a very complex model you'd better texture the different parts
> separately, trying to use the simplest projection for each part. You'll
have
> also better control on the relative scale of the textures between parts (a
> common issue for multi-part models that are already uv-mapped).
> Now, not all textures require uv-mapping and many times one can get away
> with traditional  procedural mapping. What is a "carbon texture" exactly?
>
> G.
>
> -- 
> **********************
> http://www.oyonale.com
> **********************
> - Graphic experiments
> - POV-Ray and Poser computer images
> - Posters
>
>


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