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:
