- 4 - 
The following report on "Photogrammetric Distortion" by Dr. 
Scholer defined the term "distortion" as a symmetric rotation of 
the image point between the mathematic model of the perspective 
projection and the point physical image. 
The sum of an unavoidable tolerance in the construction of the 
optical system overlaps said physical distortion, wherefrom the 
term "deformation" has been derived. 
Some further discussions led to the conclusion that at the 
present knowledge level other factors may occur in the model 
production which cannot yet be entirely defined. 
However, assuming that model deformations may be originated by 
a faulty geometry of the photogram, it could be advantageous to 
compensate them by means of correcting surfaces analytically 
established. 
Further critical comments were then made on the conventional 
and classic solutions generally adopted. 
Dr. Schwebl reported about the importance of the digital 
technology for the photogrammetric field, specifically for the 
out-of-line processing, such as the block triangulation. 
Photogrammetric technique with out-of-line calculation has 
achieved such a level at present that it is now possible, for the 
first time, to fully use the accuracies that can be obtained by 
photogrammetric devices. 
An essential question for the future in respect to manufacture 
of photogrammetric devices is to what extent said digital 
technology can be used to increase efficiency of devices, i.e.