John M. Dlugosz heeft geschreven in bericht <36c7c155.0@news.povray.org>...
>A photograph using a wide angle lens will show distortions, such that
>buildings, which are vertical, appear bent.


In photography, with good quality lenses and with the film-plane and
object-plane parallel to each other there should be no distortions of the
kind you discribe. As soon as these planes are not parallel, the perspective
changes. Buildings start falling over. ( You can shift, tilt and rotate the
lens-plane any wat you want, it has no influence on the perspective).

When using fish-eye and super wide angle lenses, you wil have bend lines in
your picture. These are not perspective distortions, it is a result of the
central projection. If you watch the picture from the right distance the
perspective will appear normal. The normal viewing distance is the
focaldistance of the lens multiplied by the enlargement of the negative.
This goes for all pictures, not only for wide angle ones.

To prevent building from falling over, instead of tilting the camera, one
should keep the planes parallel and translate the lensplane up. This can be
done with fieldcameras or shift-objectives. In POV it can be done by
shearing the camera.

ingo

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Met dank aan de muze met het glazen oog.

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