Thank you all for your precious advices.
Now I understand what I have to do. (and the results seem quite good :-)

thank you

Simone


Alain <ele### [at] netscapenet> wrote:
> zorro nous apporta ses lumieres en ce 31/07/2006 10:37:
> > Hi everybody.
> > I find POV-ray very useful to test my computer vision algorithm.
> > However I don't understand how focal length works. In particular after
> > rendering my image I need to get the rays back from the image pixel, or
> > better, given a image pixel at coordinate (x,y) of the image, I want to
> > associate to it the relevant ray that passes through the pinhole of the
> > camera (namely, its 3D equation).
> >
> > For my preliminary experiments I use the simply standard camera
> > camera
> > { location <0, 0, 0>
> >   direction <0,0,-1>
> > }
> >
> > So I was wonder what is the value of focal length (1?), so that if I have
> > the pixel in (15,12) in the image (with the origin set in the middle of the
> > image) what is the equation of the ray associated to that pixel? How this is
> > also related to the resolution of the image?
> >
> > Thank you.
> >
> > Simone
> >
> >
> The default camera is similar to a pinn-hole camera. Pinn-hole cameras don't
> have focal lenght because they don't have any optics.
>
> --
> Alain
> -------------------------------------------------
> WARNING: The consumption of alcohol may lead you to think people are laughing
> WITH you.

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