Here are the results of an unrolling strategy I've had in mind for awhile. I
finally sat down and finished it. A generalized version of the scene file is in
p.b.s-f. I didn't implement this a macro because of it's dependence on the
camera. You really need the whole scene file.

This can be useful for several things, but primarily the results can be used as
a background image in a paint program to help align texture details when
cylindrically or spherically mapping objects not supporting UV-mapping. You
could also use it to support uv-mapping 'in reverse' (so to speak) if you use it
as a target in an image morphing package (i.e. Hijaak Morph)


--
light_source{0,1}#macro c(J,a)sphere{0,1pigment{rgb z}scale a translate J+O}
#end#macro B(R,V,O)c(0,4)intersection{c(V,R)difference{c(-z*4x+10)c(-z*4.1x+
10)c(0<7.5,45,5>)}}#end B(12,0z*25)B(8y*4<0,12,50>)          // Batronyx ^"^

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Attachments:
Download 'unwrapSkull.jpg' (25 KB)

Preview of image 'unwrapSkull.jpg'

Quake skin modelling? :)

Grim

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Batronyx wrote:
> 
> Here are the results of an unrolling strategy I've had in mind for awhile. I
> finally sat down and finished it. A generalized version of the scene file is in
> p.b.s-f. I didn't implement this a macro because of it's dependence on the
> camera. You really need the whole scene file.
> 
> This can be useful for several things, but primarily the results can be used as
> a background image in a paint program to help align texture details when
> cylindrically or spherically mapping objects not supporting UV-mapping. You
> could also use it to support uv-mapping 'in reverse' (so to speak) if you use it
> as a target in an image morphing package (i.e. Hijaak Morph)

This image looks very weird.

Can you explain a little bit more about
what you are doing ?

Are you "moving" around a mesh on the
surface of a cylinder and recalculating
3 coordinates relative to the 2D-surface
of the cylinder ? And thereafter regene-
rating the whole surface with these new
coordinates. ?

(Two coordinates being cylindrical co-
ordinates and a third coordinate being
the distance from the mesh surface
to the surface of the cylinder. ?)


Tor Olav

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"Tor Olav Kristensen" <tor### [at] hotmailcom> wrote in message
> Can you explain a little bit more about
> what you are doing ?

Sure.

>
> Are you "moving" around a mesh on the
> surface of a cylinder and recalculating
> 3 coordinates relative to the 2D-surface
> of the cylinder ? And thereafter regene-
> rating the whole surface with these new
> coordinates. ?

Nothing that complicated. The net result is the same but it isn't limited to
meshes. I just take an object and use image_width + 1 number of copies. Each is
rotated 1/image_width degrees and has a 1 pixel wide slice taken from it (using
three intersecting planes as a clipped_by object) and translated into place. The
extra copy is because I leave the clipping object centered, so half the pixel is
on one side and half on the other.

All of this was entirely possible with 3.1, however, the new 3.5 min/max_extents
and image_width/height keywords make it much more convenient. Just include your
object file and declare it as the 'Wrapobject'(see scene file in p.b.s-f),
modify the texture if desired, and it will automatically be sized to fit from
top-to-bottom, then unwrapped.

As is, there are no lights because I like ambient 1 gradients for such things,
but you could certainly add some if desired.

--
light_source{0,1}#macro c(J,a)sphere{0,1pigment{rgb z}scale a translate J+O}
#end#macro B(R,V,O)c(0,4)intersection{c(V,R)difference{c(-z*4x+10)c(-z*4.1x+
10)c(0<7.5,45,5>)}}#end B(12,0z*25)B(8y*4<0,12,50>)          // Batronyx ^"^

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in news:3c3f4702@news.povray.org Batronyx wrote:

> All of this was entirely possible with 3.1, however, the new 3.5
> min/max_extents and image_width/height keywords make it much more
> convenient. 

Did something like that in:

Newsgroups: povray.binaries.images
Message-ID: <8EC9F6D80seed7@204.213.191.228>
Subject: Flat Cat  [~50 kB]
From: ing### [at] homenl (ingo)
Xref: news.povray.org povray.binaries.images:27132

Also doing animations with a "slit-camera" is fun, a walk through of a 
house, presented in one image.

There are several photography sites on building and using "slit-
cameras" (managed to loose a frew hundred links, so can't point to the 
best site :(



Ingo

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"ingo" <ing### [at] homenl> wrote in message
news:Xns### [at] povrayorg...
> in news:3c3f4702@news.povray.org Batronyx wrote:
>
> > All of this was entirely possible with 3.1, however, the new 3.5
> > min/max_extents and image_width/height keywords make it much more
> > convenient.
>
> Did something like that in:
>
> Newsgroups: povray.binaries.images
> Message-ID: <8EC9F6D80seed7@204.213.191.228>
> Subject: Flat Cat  [~50 kB]
> From: ing### [at] homenl (ingo)
> Xref: news.povray.org povray.binaries.images:27132

> Also doing animations with a "slit-camera" is fun, a walk through of a
> house, presented in one image.


I didn't start hanging out here regularly until about March of 2001, so I missed
this. My first attempts were with a camera but, I wasn't nearly as successful as
you were here.

I would sigh heavily at not having had an original idea, but I don't think there
are really too many of those in life. Also I stole this idea from someone else
in another package. They used a slit-camera technique and set the thing up as an
animation with the last frame being a regular camera and all previous pics
aranged as image maps on a plane. No scripting, not a bit automated, very
inconvenient.


> There are several photography sites on building and using "slit-
> cameras" (managed to loose a frew hundred links, so can't point to the
> best site :(

I've been there (losing links) :) I'll have to look some of those up. Thanks.


--
light_source{0,1}#macro c(J,a)sphere{0,1pigment{rgb z}scale a translate J+O}
#end#macro B(R,V,O)c(0,4)intersection{c(V,R)difference{c(-z*4x+10)c(-z*4.1x+
10)c(0<7.5,45,5>)}}#end B(12,0z*25)B(8y*4<0,12,50>)          // Batronyx ^"^

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