the origin, i.e. ry:ry e1:e9. With the definition abovementioned
such a shape of the curve will correspond to the "theoretical 0-position”.
As a curious fact, the Topogon lens satisfies these requirements very
closely (at forward overlap of 60 %) as the nomograms of the vertical
parallaxes show. That means that the instrument operator using pictures
taken by means of this camera will approach the "theoretical 0-position”
without being aware of it.
Concerning these reflections a study of a lens distortion curve,
imagined as a theoretical rectilinear, will give certain interesting conclu-
sions in this respect, too.
Due to the vertical parallaxes caused by the lens. distortion, super-
imposed by the parallaxes of the tilt e, the displacement in the plane
(x, y) of any point can be examined. However, such a study is not the
subject of this paper.
38 Conclusions
As a conclusion it may be said that only the parallaxes of the original
position of the two stereoscopic pictures, here called the "theoretical 0-
position", correspond to the lens distortion curve.
Thus it must evidently be established that, basically, any relative
orientation of a pair of stereoscopic pictures will represent a "disturbed
O-position". Therefore, it must be considered as impossible to derive the
lens distortion curve from the residual vertical parallaxes. These paral-
laxes have a very problematical relation, if any, to the lens distortion
curve.