CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
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buildings (monumental, public, residential, industrial, sheds, 
roofs, covered tunnels etc.,), and other types of areas that have 
to be processed (roads, green areas, water, yards, slopes, sports 
areas, cemeteries, etc.). Some of the graphic interface windows 
are shown in fig. 2 (the main, data input and processing 
windows). 
GENEDDEM works in 3 stages (as shown in fig. 3) which are 
indicated in the processing window with a progression bar (see 
fig. 2): 
• filling the areas inherent to the buildings with their 
heights: extraction of the DXF file of the centroids, 
reading of the various polylines in sequence with the code 
corresponding to a building object, filling of all the 
DDEM grid points inside the boundary of the building; 
Data input 
Figure 3 - Flow chart of GENEDDEM 
• filling of other areas: extraction of the DXF file of spot 
heights and contour lines, reading of the polylines in 
sequence with the corresponding code of the entity, 
search for the points that are inside the area, interpolation 
of the height of the grid points inside the considered area 
on the basis of the height points and the vertices of the 
boundary polylines; 
« filling of the remaining part of the DDEM (natural 
ground). 
The file that contains the complete DDEM is then stored in 
binary form. A description file contains the number of lines 
and columns of the DDEM, the reference system and the step 
of the grid so as to make it directly usable by the ACCORTHO 
module or by one of the many commercial packages available 
on the market, suitable for digital image processing (for ex.: 
ENVI). The interpolation techniques that have been 
implemented in the ACCORTHO package are in short: closest 
points, minimum square planes, bilinear and bicubic splines 
[Brovelli, 2002]. 
An example of the results of the GENEDDEM software can be 
seen in fig. 4: a portion of the 3D map in scale 1:1000 of the 
Municipality of Turin (map no. 112) is shown in part (a), the 
display of the derived DDEM (with a step of 20 cm, which is 
suitable for orthophotos in scale 1:2.000), is represented in part 
(b) as an image where a grey scale corresponds to the heights. 
The processing time required about 1 hours (for the entire 
sheet of 6600x5500 points, interpolated by bilinear splines), 
using a standard PC equipped with a Pentium IV (1,5 GHz - 
512 Mb RAM). 
Figure 4 - An example of an elaboration with GeneDDEM: 
(a) digital cartography, (b) grey-level image of DDEM 
3. EVOLUTION OF THE ACCORTHO MODULE 
Concepts and algorithms of the ACCORTHO module have 
remained basically the same as the first version [Boccardo et 
al., 2001]. The changes that have been implemented in the last 
year refer to the operative and optimisation problems with the 
purpose of making the software suitable for a massive 
production. 
In short, the main changes that have been made are: