¢) 
gt 
  
   
provides the user of the map with the elements of trusting the work 
and the maker with a test of the goodness of the employed methods 
and a guide to the rational modification of these methods - but 
it is also economic too, as testing gives the buyer a method of judgement 
of the real value of the purchased topographic map, and the maker, 
the possibility of reducing to the minimum the cost of production 
without depreciating the technical value promised to the buyer. 
€ 
1. 2. Methods in use. 
Long before the methods of photogrammetric survey were adopted, 
in Italy and abroad some State organizations, to which works of general 
cartography were committed, as for instance our Geographic Military 
Institute and the General Direction of Cadastre, were in the necessity of 
studying methods to check the accuracy of the work made by the 
technicians of the organizations themselves or by private surveyors, to 
whom the works of general cartography were totally or partially leased 
out. A very well organized methodology of testing, for works made by 
the classic survey methods, has risen as a natural consequence. In the 
beginning, the photogrammetry was only used for special purposes for 
which the terrestrial photogrammetry was particularly fit; later on, as 
aerial survey, it took resolutely the place of the classic methods beside 
these important State organizations, which partially modified their 
equipments and accepted the aerophotogrammetrie contractors by the 
surveyors-contractors equipped for the tacheometric works. Then it 
was necessary to transfer the old systems of testing from the old methods 
of working to the new ones. In fact it was inconceivable to accept a 
method still hardly known, and loose at the same time the system which, 
for many years, had been useful to assure the goodness of the topogra- 
phic maps, made under the responsibility of the mentioned organiza- 
tions. The testing of the goodness of the planimetric surveys made by 
means of tacheometry, then included, and now include, for instance: 
the investigation of the angular and linear closing errors of the triangles; 
the investigation of the angular and linear closing errors; the maximum 
length, the maximum slope, etc. of the tacheometric traverses; the 
investigation of the comparison between measurements of relative 
distance between near and distant points; that is to say a whole of 
checks - that perfectly adhered to the work performance with the 
tacheometric systems. So that the tests based on the quantity of the 
determined points and on the comparison between multiple and 
reiterated measurements, are suitable for surveys of elevation planes