n ; fact 
S. Dro- 
of light 
ection- 
than a 
paral- 
whether 
of the 
whether 
ose of 
a] 
map can 
e there 
on the 
center 
ophoto- 
extreme 
urgency also pre-existing "flights" can be used, but in such a case there 
could be the above said inconvenience since the schedule of the "flight" 
has not been prepared for this purpose. 
At this stage if we take into consideration the methodology which we 
suggest for the realization of a forecasting map of the slopes stability, 
it is plain the great advantage in terms of times, costs and precision of 
the final result which we have, by using stereoscopic orthophotomap. In 
fact we remind that our methodology foresees the preparation of some ele- 
mentary maps as the lithologic map, the map of natural slopes, the map of 
the strata attitude, that of the actual use of the soil (land-use) with 
included all data concerning the anthropic activity and the geomorphologic 
map; by "crossing" these maps and through the aelgebraic sum of weights 
and values given to the individual elementary phisic .lLaracteristics, we 
obtain the final map of the stability. But the orthophotomap already 
faithfully represents the utilization of the soil and includes all data 
concerning the other parameters: lithology, geomorphologic  characteris- 
tics, etc., with the great advantage to be in the meantime, both a rigor- 
ous document from the metric point of view and to be stereoscopily ob- 
served so obtaining an easier and more correct interpretation of the par- 
ameters. 
Besides it must be added that the orthophotomap can be produced with 
the contour lines or not (it would be more correct to speak, in this case, 
of orthophotoplane); in the latter case, which we prefer for the greater 
"cleanness" of the cartographic support, there is the possibility to over- 
lap an elevation plane whose density is fixed by the user depending on the 
requirements of the work to be done; therefore the orthophotomap can sup- 
ply informations also from an altimetric viewpoint, namely about the dif- 
ferences in height and about natural slopes. 
In case of an orthophotoplane we suggest a simplified  toponomastic, 
only few names, so that to enable an easier reading of the document. 
Finally, as concerns the scale of this thematic cartography, we have 
chosen the 1/10.000 scale since it enables a good detail and in the mean- 
time makes it possible to obtain a good unity vision of the area to be 
studied, by dimensioning the map in a rather limited way so that it can 
be used in a comfortable and practical way. 
It must be finally observed that the scale 1/10.000 is one of the