The basic input data for the production of the
DEM were contours with a good density (10-m
contour interval, as well as 4 or 2 m in some specific
regions), together with elevation points and drainage
network. Having then this kind of data available, the
Topogrid algorithm of Arc/Info version 8.2 was able
to generate the proper grid of elevation (ESRI, 1997;
Vassilopoulou, 1999). Before the application of the
Topogrid algorithm, the data needed to be preprocessed.