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Title
New perspectives to save cultural heritage
Author
Altan, M. Orhan

CIPA 2003 XIX"' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
547
aiOCK SCANS
TARGET
PTSortgimü
cloud
<4008
pt5 mo#
cloud
-4*0
PTS vwnpieo N. cluattr
cloud /cloud
X10B3 M
TsitKGt.es
T'-COC
TRIANGLES
decimated mesh
SI2S .OBJ
format
;J3
lato dx 10
6
7.354
6.645
4 494 4
8.920
2.141
81.233
fondo dx I 3
5
2.826
2.253
1.042 1
1.993
478
17.959
parte sx, 7
6
7.614
5 847
3.535 4
6.779
1 627
61.171
complet I
model
17
17.794
14.745
8.071 9
17.692
4246
160.363
Figure 8. Cloud point sample.
A “curvature sample” operation was performed
(with Raindrop Geomagic Studio software).
Points that lie in a high-curvature region remain in order to
maintain the accuracy of the surface curves. In this way it has
been possible to halve the acquired points
Figure 9. Clusterization of range map
(Figure 11), to refine and correct imperfections or errors in the
surface. The clusters, previously defined has been converted in
a mesh and then an optimization has been performed. In order
to preserve surface integrity and details, a method of polygon
decimation (based on shape preservation), allowing the number of
triangles to be reduces while maintaining the overall shape of the
object has been employed. A comparison between the final resulting
mesh and the original acquired cloud of points has been carried out.
The deviation is displayed as a colour map (Figure 12). Although
the original measured data has been reduced by about 15-20%,
shape description is both satisfying and accurate from a metric
Figure 11. Example of mesh optimization
Figure 12. Comparison between the final resulting mesh and
the original acquired cloud of points. As side color scale
shows, green indicate deviation <±0.005 m
Figure 13. Assembled model
point of view. At the end the entire model has been assembled in a
reference system and overlapped with photogrammetric restitutions,
also available for the apse (Figure 13).
The application of new survey techniques has to be able also to
produce standard graphic elaborations with these requirements
consolidated in time; so, simple renderings can be considered a
base to extract vector data (Figure 14). In this way it is possible
Figure 10. From point to surface: example of triangulation
Figure 14. Examples of manual edge extraction