2.3. Geographical location of single informations by means of orthophotos 
Aerial photographs and film strips from scanners of high mountain ter 
rain are subject to rather substantial geometrical distortions. To compare 
different information in different data-sets of the same areal unit with 
each other their exact location within a coordinate system is absolutely 
necessary. This is achieved by a gridcell sampling technique. The construc 
tion of such a systemic grid on the very heterogeneous photographic material 
regarding scale and distortions would be most unpractical. Therefore the 
different interpretation results first had to be transferred onto a uniform 
data-base (Lit. 8). The most convenient form for such a data-base for high 
mountain terrain presents the orthonhot ography (Lit. 9). Almost all impor 
tant surface features and their boundaries recognizable on aerial photographs 
are visible on the orthophoto, too. This allows a relatively simple, fast and 
accurate transference of the interpreted data onto the general data-base. 
On the other hand the number of identification points in maps of high moun 
tain terrain is limited and insufficient, and the transference with instru 
ments in extreme relief not precise enough and uneconomical. In addition 
the oblique photographs could be oriented easily with the aid of the ortho 
photos. 
2.4. Quantification of data and storage in a data-bank 
Besides the qualitative results an addition of quantitative informa 
tion and the organization of the data for geoecological applications is 
essential. The arrangement of the data in matrix form and the compilation 
of a data-bank allows an easy further processing and outputs in various 
ways, such as: 
- printer maps of whatever element(s) and changes are desired, 
- statistics, tabulations, areal measurements, 
- graphical presentations, 
- calculation of ecological correlations, 
- print-outs of an element (or combinations of elements and changes) in cor 
relation to another element (or elements) (e.g. the distribution of a 
specific plant in relation to various features such as soil moisture etc.). 
The interpreted data is transferred onto the orthophoto and then 
sampled for each gridcell, coded and stored in matrix form. The quantitative 
information and the coding of the qualitative information in alphanumerical 
form has to be considered carefully, and individually for each feature. The 
number of categories into which each feature is divided has not to be equal, 
but for the different data-sets of a single feature (e.g. the different 
situations of the snowcover) the same categories should be used. 
For the Grevasalvas test site the grid was placed over an orthophoto 
1 : 5'000, and oriented in accordance to the national coordinate system, 
allowing an integration of the local information system into the existing 
national data-bank. The grid width depends on the size of the area under