161
Chapter VI
B) SYNTHETIC EVALUATION OF RESULTS
by
Mariano Cunietti, Secretary of the Group.
1 - GENERAL CONSIDERATIONS
Usually, the blocks of strips are carried out for cartographic aims. Therefore,
in our opinion, it is suitable to investigate, in terms of their cartographic appli
cations, the characteristics of the results of a block, on the basis of which one can ex
press a judgement of merit.
Generally, from triangulation and adjustment of a block, one obtains the coordi
nates of a series of points on the ground, on which the single models will be oriented
afterwards, during the cartographic plotting.
Therefore, the plotting itself will be influenced by the effects of all the errors of
absolute and relative position of the points on which each model will be oriented.
The errors of absolute position cause a displacement of the model without de
forming it; the errors of relative position change the position of a model with respect
to that of the next, deforming it considerably and creating discontinuities which are
very harmful to the cartographic plotting.
It is impossible to establish a priori which of the two consequences is to be avoided
more. The purpose of the map, its scale and the nature of the ground influence the
situation markedly. In the case of our experiment, which considers very small scale
cartography (1:100.000), the second error is to be considered more important than
the first.
Therefore, if one wants to summarize by means of a few indices the elements
most significant for the description of a block, it is necessary to search for a suitable
principle to first separate, and then to express synthetically the following three char
acteristics:
a) asymmetry in distribution of the errors;
b) general behaviour of the errors; wide and slow oscillations of the errors;
c) local irregularities; short and rapid oscillations of the errors.
If one could obtain by means of completely objective procedure the three above
mentioned indications, synthesized in three numbers, the complete judgement con
cerning the results of an experimental test would be more convenient and the measure
of the precision of a block would be significant also from a practical point of view.