Hmm, I'm no art major and I have no experience with photography so I'm
probably gonna use lots of made up terms when I try to explain what it is
I'm after. Just bear with me :)

I've got this great idea for a scene in my head (don't we all :) but I'm
having trouble setting up the camera. I'm sure there is an easy way to do
this, in any case I certainly HOPE there is! I have the camera in the exact
position I want it in, I have the look_at and sky vector set as well and
everything is going great but... I want to move the vanishing point. The
look_at vector IS the vanishing point and I have it right where I want it,
but I don't want the look_at vector to be in the center of the image.

I wish I could find a good example of what I'm trying to explain. This was
the best I could do.

http://www.harcourtschool.com/glossary/math/images/vanishing_p8.gif

see how the vanishing point is up at the top left not the center of the
image. Thats what I'm going for. So how can I do this?

Thanks,
Corey

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Corey Woodworth wrote:

> I wish I could find a good example of what I'm trying to explain. This was
> the best I could do.
> 
> http://www.harcourtschool.com/glossary/math/images/vanishing_p8.gif
> 
> see how the vanishing point is up at the top left not the center of the
> image. Thats what I'm going for. So how can I do this?
> 
> Thanks,
> Corey

You don't actually set the vanishing point in POV.  Instead, the camera 
points in a direction such that the camera points from the "location" 
vector to the "look_at" vector.

The field of view is set with (IIRC) the angle parameter.

...Chambers

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Just move the look_at point and/or the location point and the vanishing
point will be in some other part of your image.

In the image you posted, the location is to the left and above the box,
and the look_at point is slightly below and to the right of the center
of the box.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:  http://rsj.mobilixnet.dk (updated Apr 14)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
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On Thu, 2 May 2002 01:24:36 -0400, Corey Woodworth <cdw### [at] mpinetnet> wrote:
> see how the vanishing point is up at the top left not the center of the
> image. Thats what I'm going for. So how can I do this?

AFAIK there is no other way than cropping the output. Someone did this
in IRTC once (some kind of architectural theme): he wanted the vanishing
point to be near the bottom of the image, so he made the image something
like 1000 pixels high but cropped 400 rows from the bottom out of the
final image.

-- 
Antti Arola, edistyksenvastainen retropaskiainen

This message written by a complete asshole.

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Antti Arola <aar### [at] lutfi> wrote:
> AFAIK there is no other way than cropping the output.

  It should be possible by shearing the camera in the exact same way as
shearing the box in:
http://enphilistor.users4.50megs.com/matrix.htm

  You can use the Shear_Trans() macro in transforms.inc to do this (I think
that some camera optimization had to be turned off in order for this to
work but I don't remember now which one; POV-Ray should give a hint in its
warning/error message).

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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> You don't actually set the vanishing point in POV.  Instead, the camera
> points in a direction such that the camera points from the "location"
> vector to the "look_at" vector.

You're misunderstanding me. I don't want to change the actual look_at vector
because my camera is looking where I want it. I want to move the location of
the look_at vector in the output file. In other words I have the look_at
vector where I want it in 3D space, but I don't have it where I want it in
2D space.

I really wish I could explain this better :)

Corey

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"Antti Arola" <aar### [at] lutfi> wrote in message
news:slr### [at] skavaraese...
> On Thu, 2 May 2002 01:24:36 -0400, Corey Woodworth <cdw### [at] mpinetnet>
wrote:
> > see how the vanishing point is up at the top left not the center of the
> > image. Thats what I'm going for. So how can I do this?
>
> AFAIK there is no other way than cropping the output. Someone did this
> in IRTC once (some kind of architectural theme): he wanted the vanishing
> point to be near the bottom of the image, so he made the image something
> like 1000 pixels high but cropped 400 rows from the bottom out of the
> final image.

Yeah Cropping the output occurred to me, but the image I'm planning will
probably take a good deal of time to render so I was hoping I could avoid
rendering extra lines.

Corey

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"Warp" <war### [at] tagpovrayorg> wrote in message
news:3cd123bb@news.povray.org...
> Antti Arola <aar### [at] lutfi> wrote:
> > AFAIK there is no other way than cropping the output.
>
>   It should be possible by shearing the camera in the exact same way as
> shearing the box in:
> http://enphilistor.users4.50megs.com/matrix.htm

Thanks! I'll look into that and tell you how it goes :)

Corey

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Corey Woodworth wrote:

> Yeah Cropping the output occurred to me, but the image I'm planning will
> probably take a good deal of time to render so I was hoping I could avoid
> rendering extra lines.


You don't have to render the parts you don't need.

You can start and end the render at the rows and columns you need. 

Look up General Output Options in the help file.


/Ib

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What you are trying to do is very similar to the long discussion
of creating a stereo camera by shearing. Both involve using
shearing to accomplish cropping that could be done in
post processing. (see the Stereoscopy thread above).

Harold

"Corey Woodworth" <cdw### [at] mpinetnet> wrote in message
news:3cd14940$1@news.povray.org...
>
> "Warp" <war### [at] tagpovrayorg> wrote in message
> news:3cd123bb@news.povray.org...
> > Antti Arola <aar### [at] lutfi> wrote:
> > > AFAIK there is no other way than cropping the output.
> >
> >   It should be possible by shearing the camera in the exact same way as
> > shearing the box in:
> > http://enphilistor.users4.50megs.com/matrix.htm
>
> Thanks! I'll look into that and tell you how it goes :)
>
> Corey
>
>

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