The work was to the entire satisfaction of the body controlling this
operation (Corporation for the Reclamation of the Pontine Marshes) and
the checking work is at present in progress.
At the present moment the LS.A. is carrying out an important survey
of a similar nature in Sardinia in collaboration with the Società E.LR.A.
of Florence and so far the results are stated to be excellent.
THE « NISTRI» PHOTOCARTOGRAPH FOR PLANNING BASINS,
CANALS, PENSTOCKS ETC.
In order for a photographic aerial survey to be profitable, it is neces-
sary that the zone to be surveyed should be of a certain density or that
the area of the survey should be such as to permit of the general organi-
sational expenses, which are fairly considerable in such surveys. In fact,
even the transfer of the aeroplane represents no small expense. It is for
this reason that for surveys in regard to enterprises of this type, in view
of the small area of ground which usually has to be covered, a photogra-
phic survey carried out on the ground is most indicated.
Notwithstanding, jobs of this type have often been carried out, espe-
cially when it has been possible to combine several jobs in such a way
as to share the expenses of photographic coverage.
A survey was made by the L.S.A. in regard to a plan for a hydro-elec-
tric reservoir on behalf of the AMGA (Municipal Gas and Water Under-
taking) in the neighbourhood of Genoa.
A map was drawn on the scale of 1:2000 with contours at every 2m.
For this operation too it was thought wise to integrate the altimetric part
with the dimensions obtained by classical survey methods. In point of
fact, however, this was only a precautionary measure because the dimen-
sions obtained in this way were exactly the same as those from the older
methods.
The work carried out gave complete satisfaction to the authority in
question and fulfilled its task admirably.
In the Exposition attached to the Congress there are to be seen several
copies of large-scale cadastral maps and engineering plans carried out by
the aerial survey units of the « Nistri » Photogrammetrical Institute.
