INFLUENCE OF ANALYTICAL AERIAL TRIANGULATION 
PERFORMED WITH STEREOCOMPARATORS AND 
ELECTRONIC COMPUTORS IN THE CONSTRUCTION 
AND USE OF PHOTOGRAMMETRICAL PLOTTERS 
Some years ago precisely in 1935 when speaking to the students of the 
ist Course in Photogrammetry at the Politechnic Institute of Milan, I said a few 
words about the commercial problems in new photogrammetrical activities, which 
were then taking the first steps, and indicated the possibilities offered by the 
existing instruments. 
Today I return to that subject because the arrival of electronic computers has 
caused a revolution destined to qualify photogrammetrical instruments and their 
practical use. 
It is well-known that the economical problem of the photogrammetrical industry 
is the maximum possible reduction of operations in the field, for which reason the 
Jlotters themselves are entrusted with the performance of triangulation which must 
furnish the necessary elements for the reconstruction of the optical model and for 
its absolute orientation. It is known that this necessity requires that first order 
plotters have special characteristics and a remarkable accuracy in construction in 
order to attain the highest degree of precision, which determine the high cost and 
decrease the economical output, uselessly aggravating the fundamental service, 
which is plotting. 
The arrival of stereocomparator recorders, in conjunction with the new electronic 
computers, solves this problem and opens the way to new prospects, both in ope- 
rational techniques and plotter materializations, for the purpose of reducing the 
costs, which until now were too high due to the previously mentioned reasons. 
[Integration of the electronic computer with the stereocomparator is designed 
to substitute for plotters of first order precision, in the performing of aerial 
triangulation. 
The stereocomparator 1s a much more accurate instrument than the first order 
plotter because it does not have the optical and mechanical exigencies which are 
required for the formation of the optical model in such operations. The average 
accuracy supplied by it is in the range of two microns, which is greatly superior 
to the approximation allowed in the determination of the position of each point 
on the photographs, due to the nature of the means used for the exposure. 
The stereocomparator simultaneously supplies the recording of the data in clear 
and on punched tape (or cards), according to the desired code, which can be 
directly inserted in the computer, which performs all the operations for which it 
Was prc ;grammed.