4 — Rules for air photogrammetric surveys on large scale
by the Administration itself with its own means, contemporary or a little later to
the accomplishment of each single operation by the enterprise.
For example, beside the control points normally determined by the en-
terprise for orientation of the pairs of photographs, the Administration deter-
mined for its own account the co-ordinates as well as the height of some other
points (points for preliminary testing). These elements were used during the
plotting work for controlling whether the enterprise has carried out the recon-
struction of outer orientation with the necessary care and accuracy.
For some small areas and by means of its own personnel, the Administra-
tion carried out tacheometric surveys of boundaries and limits of property as
well as of topographical lines, buildings, etc. During the photogrammetric plot-
ting, the representation obtained could be compared in this way to the one desum-
ed from the tacheometric survey.
The control system as described above was of great importance during
the first years; besides the guaranty afforded to the Administration as regards
the regular accomplishment of each single operation, served for training of
personnel and made possible the gradual improvement of the practice of air
photogrammetric surveys for cadastral purposes; it made possible also the ascer-
tainment and the elimination of several imperfections and sources of errors and
furnished abundant data for statistics and researches.
The fore-said initial regulations and especially those regarding the preli-
minary control, were co-ordinated after a ten years of application and collected
in the volume: « Cadastral mapping by means of air photogrammetry. Rules for
the Control Service ». The regulations were issued by the Italian Cadastral Sur-
vey in 1944 and may be valued as a considerable contribution given to the
field of photogrammetry.
However, the rapid evolution of air photogrammetry and the always lar-
ger development of its applications let the fore-said Rules appear soon as sur-
passed.
The controls carried out for preliminary testing appeared too expensive
and not absolutely necessary after the conclusion of the experimental stage of
cadastral mapping: by means of air photogrammetry; further such controls would
have delaid or even hindered the rapid accomplishment of air surveys of vast
areas. Having to-day both the enterprises and the Administration well-trained
personnel at theis disposal, a simplification of the controls appeared justified,
provided that precise regulations would be issued as regards the proceedings
and operations of air photogrammetric surveys.
