Banchini, Giovanni 
  
industrial parks, residential areas, principal electric, telephone gas,etc. lines). The topographic map that best fits these 
requirements would be the 1:50 000 scale because of the area it covers (600 sq.km) and its informational content. 
Unfortunately the existing cartography is not homogeneously updated and, more than that, is not available for the entire 
country. 
The tools for the second level cartography or the working level should permit the delimitation of the areas at 
risk and their subdivision in classes of risks. It should be possible to place in evidence terrain morphologies subject to 
hazards such as river banks in the case of flooding. The vertical resolution of this instrument should be less than 2m and 
it should be spatially homogeneous and updated. 
Where the terrain morphology or the type of risk require a high planimetric or altimetric precision level for a 
correct interpretation of a problem, if one were to prepare a flood inundation map of an area for example, it would be 
necessary to prepare an instrument ad hoc. This would constitute the third level or that of detail. It would include those 
circumstances where small differences make large area impacts or where points on the ground need to be determined 
and portrayed with great precision (geologic faults). 
Often it is very useful, at times it is compelling, to have a historical documentation of an area subject to 
hazards. In these circumstances the availability of an aerophotogrammetric archive becomes particularly significant. 
LAND INFORMATION FOR AID AND RECONSTRUCTION 
The analysis of damages induced by a landslide represents a vivid and easily understood example of the 
superiority of the digital orthophoto with respect to the classic cartographic map or the simple aerial photography. Here 
the updating of the terrain informational content and the quick production time of the orthophoto are considered 
essential to assess with certainty: 
the type of damages following the occurrence of a specific disastrous event 
the accurate quantification of the geographic dimensions of each area with a given class level of damage 
a reliable estimate of damages 
the scientific planning of the use of the human, financial, and material resources needed for emergency 
assistance and reconstruction 
A conjunctive quantitative and qualitative analysis would not be possible with only the aerial photos because 
of the terrain relief that introduces in the photo a continuous variation of the image scale not to mention the distortion 
brought about by the aircraft movements. Use of the existing cartography would be useless because, obviously, it does 
not portray the damages. The use of both the aerial photography and the cartography would, at best, only permit a 
qualitative analysis of the hazard 
With the digital orthophoto the user can perform additional tasks to those listed above, specifically 
Enlarge the image to examine qualitatively specific areas of interest beyond the metric capability of the 
orthophoto to evaluate aspects only available from the information content of the aerial photo 
Overlay the orthophoto image with vectorial data originating from other sources (thematic maps) 
Associate objects on the orthophoto with alphanumeric information arising from different databases 
AFTER THE EVENT LAND INFORMATION 
The emergency following immediately after the occurrence of an environmental disaster requires the 
availability of information on the landscape for an optimal use of the resources at hand. Time enters here into the 
picture and a large part of the data and the parameters that describe the landscape, whether they are geometric, geologic, 
biologic or human, become modified with time. Mostly it means slow variations that bring about an outdating of the 
information and the related documents so that a constant job of updating is to be expected. But in addition to these slow 
and progressive variations in time, environmental disasters introduce immediate variations on the landscape. In these 
cases the whole matter of spatial information becomes atypical and must be dealt with very realistically. It may be 
divided under 4 fundamental needs along equivalent chronological moments: 
Knowledge of the most recent preexisting conditions of the area 
  
108 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.