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- 1363 - 
CONTRIBUTE OF STEREORTOPHOTOMAPS 
IN THE SLOPES STABILITY STUDY (*) 
by 
E. Amadesi, G. Orlando, G. Vianello 
The thematic cartography in general and particularly that of geologi- 
cal-application type, needs, especially if it is on a medium large scale, 
an up-to-date basic cartographic support. 
Regrettably the existing topographic maps have not, in most cases, 
such a qualification, since they are an old edition, and besides often 
present medium-small scales. 
The orthophotography then supplies an adequate solution of the prob- 
lem which many users have to obtain (within a limited or, at any rate, 
short period of time) a representation of the soil with a determinate 
scale on which they can also take measurements, namely determinations with 
metric characteristics. 
Infact the orthophotomap turns out to be cheaper and accomplishable 
within a shorter time than that necessary for traditional cartography; 
besides it is up-to-date in all visible details (and not in some details 
only, as generally occurs in case of the up-to-dating of some old topog- 
raphic maps) and has the most suitable scale for the purposes of the work 
and is easy to be read by everyone, techniciens and ignorants of this 
Science. 
Some statistical studies enable to ascertain that the preparation of 
an orthophotomap can be effected within a time 4 or 6 times minor than 
that necessary to produce a correspondent hachured map; the cost would be 
approximatively the half of that to be paid for a traditional map, by in- 
cluding however the expenses for the aerophotographic work. Under special 
circumnstances and according to the extensions of areas to be covered such 
a cost can be also lower than that above mentioned. 
Naturally also the orthophotomap like all the topographic maps has 
the only disadvantage to supply news limited to the planimetry; should the 
data included in a stereoscopic model and present in the orthophotomap be 
(*) C.N.R., Finalized Program: Soil Preservation; Sub-project: Slid- 
ing Phenomena; Publication n. ; Institute of Geology, University of Bo- 
logna (Italy).