CI P A 2003 XIX"' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
6. RAPID PHOTOGRAMMETRIC SYSTEM FOR
EMERGENCY SURVEY
In emergency survey, the necessity to collect in the field as much
informations as possible, as quickly as possible, is well known.
These requirements sometimes conflict with the application of
high quality metric techniques, but the research of solutions that
represent an acceptable compromise must be carried out. We will
show this work, in progress, using direct photogrammetry, even if
the object of study is not exactly an emergency situation.
6.1 Data acquisition and processing system
Cyclop system (a Menci Software product) is a revision of a
stereometric cameras principle. It enables non experts to acquire
stereoimages and to visualize a stereomodel without control points,
the most demanding survey phase. This opens up digital close
range photogrammetry to a great number of promising application
areas, for example in small object classification, in those cases
where it is impossible to signalize the object and, in general, in
emergency cases. The acquisition system is an horizontal metal
bar on a tripod, with a sledge run, on which it is possible to put
any type of camera (Figure 14). To obtain stereoimages with
known base and parallel optical axis, the sledge is fixed with a
Figure 14. Acquisition unit and reference system.
calibrated distance block. This geometric configuration guarantees
the alignment and the complanarity of the fiducial axis and assures
the acquisition of stereoscopic pairs without height-parallax. This
system allow the use of any kind of camera in order to satisfy
the requirements of the survey. It is equipped with a specific
software (SVCyclop) that allows the immediate plotting without
orientation phases. Required data are: a couple of images, cameras
distance, approximate distance from the object and camera inner
orientation. Measurements and vectorial restitution are possible
either in stereoscopic mode, with appropriate hardware, or in
monoscopic mode; in this case one image is fixed while the other
Figure 15. Two couples of images taken with Cyclop system. The
points on the images, have only been used to control the results.
Figure 16. Restitution of three models with SvCyclop.
can be moved in a window with a collimation mark. Acting on the
elevation it is possible to eliminate horizontal parallax, moving the
second image along the epipolar line. Image matching alghoritms
support the process.
6.2 An application
The system, already tested in the small objects survey (Marino,
Tucci, 2002), has been used to survey the facades of Villa Raggio
in Asti (Figure 15). A calibrated Nikon D1 (fi=24mm) has been used
at different distances. To cover entire buildings, 3 strips for every
facade have been acquired, obtaining different model scale. A
topographic survey has been carried out to measure control points
to orient the same models in another photogrammetric software
(Stereoview by Menci software) (Figure 16). So the restitutions
obtained by Cyclop, without control points, have been compared
with those obtained with Stereoview. It results that, in general,
with distance inferior to 12 m, the system works well (althougth
there are some problems to link different restitutions among them),
and it can be used in all cases where external orientation is not
possible or not required. Often, in cultural heritage the images are
the only documentation that remain; this system, that can be used
also by non photogrammetric experts, allows one to add a metric
value at the acquired images.
We have presented three different, simple applications of a survey
of cultural heritage where while the task of the measurement,
“how” to measure, might usually be solved quite clearly, the
question of “what” to measure remain a permanent problem and,
in general, requires great expertise on the part of the operator.
8. REFERENCES
Astori B., Rinaldi L., Tucci G., 1999. New survey of Morimondo
Abbey, Proceeding of the workshop International Cooperation and
Technology Transfer, Parma, 15-19 february.
Boccardo P., Dequal S., Lingua A., Rinaudo F., 2001. True digital
orthophoto for architectural and archeological applications.
International Archives of Photogrammetry and Remote Sensing,
vol. XXXIV - 5/W1, pp. 50-55.
Dequal S., Lingua A., Rinaudo F., 1999. A new tool for
architectural photogrammetry: the 3Dnavigator. Proceedings of
XVII CIPA International Symposium, Olinda, 1999.
Marino L., Tucci G., 2002. II rilievo speditivo mediante
fotogrammetria digitale: un ‘applicazione in ambito archeologico.
‘AnaGkh 33, marzo 2002, Alinea Editrice.
Tucci G., Algostino F., Bonora V., Guidi G., 2003. 3D Modeling of
Boccaccio s hometown through a multisensor survey. Proceeding
of International Workshop on Visualization and Animation of
Reality-based 3D Models, Tarasp-Vulpera 24-28 February 2003.
9. ACKNOWLEDGMENTS
The authors gratly thanks Denis Prata for his work in S.
Giorgio tavern; Marco Zavattaro and Daniela Turcato for
their work in Povil Casaforte and Stefano Bianco for his
work in progress on Villa Raggio.
