The thing that determines distortion is proximity to the image edge. Of course,
if you increase the angle to 150 degrees, the box becomes smaller in the image,
so all samples of the box are closer to the image center. This cancels out the
distortion. If the box would be at the image edge with both camera angles, there
would be a definite difference.
What I'm saying is that the distortion towards the image edges increases as the
camera angle increases. This is not perspective distortion, it is a specific
distortion of dimensions inherent to this type of mapping.

Margus

ingo wrote:
> 
> Try the following:
> put a box at origin, rotate 45*y.
> Set up your camera at a position on the -z-axis you like and keep the camera

> 

> image again but with such a bigger +w and +h that the box has the same hight,
> in pixels, as in your first image.
> Cut out the boxes of both images and compare. You will see that there is no
> difference in perspective (distorion)
> 
> Ingo
> 
> --
> Photography: http://members.home.nl/ingoogni/
> Pov-Ray    : http://members.home.nl/seed7/

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