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Rules for air photogrammetric survey on large scale — 5 
The elaboration of apposite « Rules for air photogrammetric surveys » 
was therefore retained necessary. 
These Rules were issued recently (in 1952); they regulate each single 
operation to be carried out for the production of the cadastral map by means 
of air photogrammetry, i. e. the operations from the marking of points on the 
ground before the flight to the cartographic design of the map obtained by plot- 
ting of the photographs, and to testing of its accuracy. 
The « Rules », we have the pleasure to present to the 7th International 
Congress of Photogrammetry, firstly deal with the characteristics of the areas 
where the application of the air photogrammetric survey appears more suitable. 
Further the accomplishment of each single operation necessary for the 
production of maps is regulated: these operations are the following ones: 
a) marking of points on the ground before the flight; 
b) organization of the photographic flight; 
c) preliminary reconnaissance of the ground on the hand of magnified 
photographs; 
.d) choice of control points for the outer orientation of photographs and 
determination of their planimetric position and height; 
e) plotting work (orientation of the pairs of photographs, plotting of 
planimetry, plotting of contour lines); 
f) indications for the choice of contour intervals; 
g) cartographic completion of the map; 
h) controls to be carried out during the work; 
i) final testing; 
1) degree of accuracy obtainable and limits of error. 
Besides the instructions for the accomplishment of new surveys, the « Ru- 
les» also deal with the bringing up-to-date of old maps as well as with the 
integration of planimetric maps by means of contour lines. 
The volume of the « Rules », we have the pleasure to distribute to the at- 
tendants at the 7th International Congress of Photogrammetry at Washington, 
contain therefore the entire regulations, on the base of which the Administra- 
tion of the Italian Cadastral Survey carries out or let out on lease to private 
enterprises the air photogrammetric mapping work. The regulations include 
both general and particular instructions and can be usefully applied to any other 
survey on large scale, if a high degree of accuracy like that of cadastral maps is 
required. 
The proceedings explained in the « Rules » constitute the result of the 
experience acquired by the Italian Cadastral Survey during nearly 20 years of