SETTING UP OF AN EXPERIMENTAL POLYGON IN ITALY, ECC. 
5 
various operational procedures and calculation methods have been tested. We 
believe, however, that the problem of how to obtain accurate maps at large scales 
must still be gone much deeper into. 
The Institute for Geodesy, Topography and Photogrammetry of the Milan 
« Politecnico », including also the Photogrammetry Training and Study Centre, 
has by now arrived at a very great experience in analytical photogrammetry, as they 
acquired one of the first specimens of the OMI-NISTRI TA3A stereocomparator ; 
recently they have further improved their equipment by substituting this stereo 
comparator with the more up-to-date TA3D model and buying also an APC. The 
« Istituto Geografico Militare » were among the pioneers in photogrammetry, and 
enjoy an age-old repute, conferred upon them by men like Paganini and Santoni. 
Their activities have so far been carried out exclusively by means of analogical 
instruments ; but also I. G. M. intend extending their activities into the branch 
of analytical photogrammetry and have acquired a TA3D stereocomparator. 
To get the maximum possible profit, it as been thought fit to combine the means 
at the disposal of the two above mentioned concerns in order better to tackle this 
problem. They therefore created the « Concern for research work on analytical aerial 
triangulation blocks » y, under the auspices of the National Council for Research, 
formed, as has been said, by the Institute for Geodesy, Topography and Photogram 
metry of the Milan Politecnico and by the Istituto Geografico Militare of Florence. 
2) The experimental polygon. 
The study to be undertaken concerns the operational techniques at the stereo 
comparator, both with regard to accuracy and to quickness of execution, as well 
as the calculation methods ; this will therefore imply a great number of tests and 
experiments in order to achieve the best possible results. We have to assume that it 
will be possible to know the magnitude of any errors made, and for this we have to 
dispose of as sure as possible comparison terms. 
The first steps towards the achievement of this program consist in taking pho 
tographs of a block of strips in an area which has the most varied morphological 
aspect, so as to test how it applies to the various conditions of the methods exper 
imented, then, to verify the approximation arrived at, each stereoscopic pair must 
show a certain number of points, uniformly distributed within the pair itself, of 
which the coordinates of the ground system are known with the greatest possible 
accuracy. 
The « Istituto Geografico Militare » in view of its equipment for aerial surveys 
and its organization for ground surveys, have taken it upon themselves to realize 
the polygon. The area chosen is immediately west of Florence of about 30 X 30 
sq. km size. The location and size of this area has been decided upon on the basis 
of the following considerations : 
— from the point of view of altimetry the area is made of flat, hilly and 
mountain land, as it includes part of the Arno valley, of the Albani hills and of 
the Pistoia Appennine, and there are differences in height from 500 to 1000 m ;