EXPERIMENTAL ANALYSIS OF THE INTRINSIC ACCURACY 
OF THE SANTONI STEREOCARTOGRAPH Mod. IV 
By M. CUNIETTI and A. MARAZIO 
Istituto di Geodesia, Topografia e Fotogrammetria del Politecnico di Milano 
The purpose of this paper is to report the most interesting and significant 
findings of a detailed analysis of the intrinsic accuracy of the Santon Stereo- 
cartograph mod. IV carried out at the « Istituto di Geodesia, Topografia e 
Fotogrammetria del Politecnico di Milano ». A more detailed and comprehen- 
sive report on the findings and experimental methods adopted in this research 
will be published separately. 
In this paper the Authors have restricted themselves to the study of 
the accuracy of the mechanical parts which move or control the movement 
during the plotting stage of a pair of photographs. 
As in the Stereocartograph the observing optical system of the plates is 
fixed, the accuracy of results depends on mechanical parts only, both in the 
tridimensional reconstruction of the model and in the plotting of the model 
points. 
Investigations on the accuracy of plotting instruments are usually confined 
to research into global errors occurring in both the model reconstruction and 
plotting. Investigations of this kind, which could be termed « synthetic »; 
are on the other hand the only important ones for judging the degree of ac- 
curacy of an instrument. However, as shown by some examples [1] [2] an 
analytical study, i. e. a search for the individual causes of projection errors, 
is of great use both to the operators and the makers of this or similar instru- 
ment. By « analytical research » we mean here the detailed study of the single 
parts forming the basic organs of the plotting unit, and the measurement, 
if possible, of the discrepancies between the theoretical schematic diagram 
and the mechanical construction of these parts. 
The organs observed are: 
a) the plotting co-ordinatograph 
b) the plates holding unit 
c) the projection system. 
These are, in fact, the only organs which are subjected to continuous 
Dovement during plotting. 
^H * 4 
The next three paragraphs deal with these organs one by one. For the 
sake of clarity, a general view of the instrument and a schematic diagram of 
mechanical organs and the optical system are shown in Figs. 1 and 2. 
  
  
  
  
  
  
  
  
  
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