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cases of Triangulation using independent model method both in their application phase 
and research phase are mentioned. 
This classification is clearly very subjective and it is limited to an analysis of the 
spreading of methods. In fact, consideration was given only to data concerning the 
number of photogrammetric Organizations usually employing different proceedings. 
No account was taken of the weight of each user which should obviously be propor- 
tionate to the aerial-triangulation mass of work carried out by different proceedings. 
A classification enquiry taking weights into account would have probably brougth 
about far different conclusions. 
The relative orientation is in most cases, obtained by optical-mechanical procee- 
dings of an empirical type: scarce is the application of numerical and semi-numerical 
methods. 
A very important datum is the one related to the first model orientation. 
xenerally, proceedings carried out purport a very carefully orientation of the first 
model employing all available ground-points in the model. 
Data supplied become more detailed when referring to the questionnaire query 
related to the average length of time of a model bridging. Such time length is kept 
within 1-2 !4 hours’ limit with appropriate variants due to the instrument, the num- 
ber of points and the type of ground. 
With the exception of very rare cases, strips are triangulated once only. 
News concerning the instrumental distorsion correction, atmospheric refraction 
and film shrinkage are generally agreeing. 
The former is obtained according to the plotting instrument employed, whether 
with correcting plates or by cams, and finally during the reprinting phase. 
Atmospherical refraction almost never results correct, whilst the film-shrinkage 
is adjusted through the focal distance variations of the plotting-camera, taking in 
average account longitudinal and transversal film deformations. 
Nothing is communicated about the entity of this deformation and its anomalies. 
Adjustment. — The dispersion of operating proceedings becomes even more accen- 
tuated when we wish to make a synthesis of information concerning the adjustment 
of strips. It is difficult to obtain, from the large quantity of information received, some 
common component which is nothing but the observation itself of the utmost varia- 
bility and the very significant observation of the quite general absence in practice of 
those proceedings decreed in theory. 
In general, it is possible to notice a light prevalence of adjustments obtained using 
the interpolating equations of second degree. However, frequently, there are also ad- 
justments obtained with simple pure linear deformations or with interpolating equa- 
tions superior to the second, third, forth or higher degrees. 
These last ones, are mainly for altimetrical adjustments; in fact, should one di- 
spose of a larger quantity of levelled points, as it has been mentioned before, in or- 
der to obtain that the interpolating polynomial passes through all or quite through 
all ground points, it would be necessary to dispose of a larger number of degrees of 
freedom. 
Also graphice methods of interpolation are very often used, sometimes for plani- 
metry only, sometimes for altimetry only. 
(Generally the graphic proceedings employed, are not widely described, so that it 
is Impossible to know whether they are a derivation of the graphical interpolation me- 
thod by Zarzycki. 
As already mentioned above, the common component, unaltered in everyone, 
17