Gosh.

I wanted this feature for years and never realised (till now) that is was
there from the beginning. The problem : to achieve what some real-world
cameras can do : displace the film from its
central-and-parrallel-to-the-lens typical position. Solution : using non
perpendicular camera vectors. Thanks to MR for his "vanishing point??"
question in p.newuser that made me think (at last).

So, what are the practical implications ?

A typical problem : a scene with an "horizontal camera", that is camera
location.y and look_at.y are identical. The horizon is in the middle of the
image. If you want it somewhere else, you have to change the camera - which
you might not want to -, or render a bigger image and crop it in a drawing
software (partial render helps). OR use non orthogonal camera vectors ;-)

Another use : render a tall building as seen from sidewalk height without
having a vertical vanishing point.

Camera code for the example :
----
// Do not forget to switch vista buffers off (-uv) or it won't work.

#include "transforms.inc"

camera{

  #declare Cam_location=<0,.25,-1.5>;
  #declare Cam_Horizontal_look_at=<0,.25,0>;
  #declare Cam_Real_look_at=<0,1.125,0>;

  location 0
  direction .4*z

  #switch (clock)

  #case(0)  // horizontal cam
    look_at Cam_Horizontal_look_at-Cam_location
  #break

  #case(1)  // usual rotated cam, vertical vanishing point
    look_at Cam_Real_look_at-Cam_location
  #break

  #case(2) // sheared cam
    look_at Cam_Horizontal_look_at-Cam_location
    Shear_Trans(x, y, z+Cam_Real_look_at-Cam_Horizontal_look_at)
  #break
  #end

  translate Cam_location
}
---


Povingly,

Philippe

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Attachments:
Download 'ShearedCam2.png' (37 KB) Download 'ShearedCam3.png' (35 KB) Download 'ShearedCam1.png' (39 KB)

Preview of image 'ShearedCam2.png'

Preview of image 'ShearedCam3.png'

Preview of image 'ShearedCam1.png'

in news:3bf590a1@news.povray.org Philippe Debar wrote:

> Solution : using non perpendicular camera vectors.

Now you figured it out, may I point you to the .../scenes/camera/ 
directory of POV-Ray 3.5? It contains a shear.pov :)

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
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"ingo" <ing### [at] homenl> wrote in message
news:Xns### [at] povrayorg...
> Now you figured it out, may I point you to the .../scenes/camera/
> directory of POV-Ray 3.5? It contains a shear.pov :)


Gnnnnnnnnyyyyaaaarrrrrghhhhh !!!

*sigh*


Never mind.

Sheared cameras must be a belgian architect thing ;-)


Povingly,


Philippe

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