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Practical and Constructive Criteria Basic to My Recent 
Photogrammetric Plotters 
by 
UMBERTO NISTRI 
ADDRESS TO THE VIII INTERNATIONAL CONGRESS OF PHOTOGRAMMETRY 
STOCKHOLM 1956 RY 
In several articles, published at various times in Italian and foreign technical 
reviews, I gave information about the evolution of my ideas on the final development M 
on the use of photogrammetric plotters, and I pointed out the reasons which led me fo 
develop the series of instruments that I have presented to this Congress. 
I shall not proceed here to describe these instruments nor the details of their develop- 
ment or their use, since this has been the subject of other addresses presented both at the 
preceding Congress and this one, but I shall recall what has already been said about th 
concepts which have guided me in developing each of the instruments, emphasizing both 
the new features which distinguish them and the advantages which I intended to achiere 
by them. 
In the Cadaster Review, edited by the Italian Finance Ministry, in issue No. 6 oi 
the year 1954, I wrote, and I quote therefrom: 
“In the classification of photogrammetric plotters, it is necessary to distinguish 
between the performance and the order of precision that they can furnish; it cann, 
in fact, be said that all universal plotters and only they, are classifiable among the 
plotters, with precision of the first order. Universality and precision are in fac 
independent of each other and are both independent of the principle on which the 
plotting instrument is based. For example, all plotters are suitable for both terrestril 
and aerial photogrammetry and among these, therefore, are also the plotters base 
on the principle of the direct optieal projection, when particular planned measure 
are taken in the course of the plotting; there can even be, for determined categories 
of instruments, a major or minor aptitude for determined performance; there is no 
doubt that the twofold application, to terrestrial and aerial photogrammetry, is more 
easily realized in plotters of the stereoscopic binocular viewing type, which are more 
suitable for plotting from photographs with axes tilted at any angle with respect to 
the plane of orientation. But universality of use involves higher costs for the instr 
ments, because, whatever be the principle by which the identification of the spatial 
direction of the corresponding rays is accomplished, the universal plotters always 
turn out to be of a more complex and delicate enough structure. 
“On the other hand, the now general use of aerial photographs with quasi-vertical 
axes, a use which has received a notable impulse because of the new wide-angle lenses 
and the ability of aircraft to achieve altitudes believed unreachable a few decades 380, 
has eliminated the need to resort to tilted photographs to cover a broader lateral 
field, so that the use of universal instruments in this respect has become 
nient than that of cheaper and more simple plotters, which are more easi 
have an advantage in the factor of precision because of their simpler structure. 
less conve: 
ly used and 
tend to prevail more than wi 
d in the machine tool field à 
design a machine 
«This economic viewpoint, plus that of specialization, 
versality in photogrammetry also, just as it happene 
modern industry, where it was realized that it was necessary to 
especially for the type of work which it was called upon to perform. ; 
“That this concept can now be considered as fully accepted is seen from the tendent] 
of manufacturers to design ever more simple instruments, although each firm keeps 
  
    
    
  
  
   
   
   
  
  
    
   
   
   
   
   
  
    
  
    
    
   
     
   
     
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