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

CI PA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
632
5. CASE STUDY: THE GRAND RIBAUD ESTRUSCAN
WRECK
The Etruscan wreck discovered in 2000 by Mr. H.G. Delauze
(COMEX, a French commercial salvage and diving company)
has been dated to the between the 6 th and 5 th century B.C. and
sits in 60 metres (197 feet) of water off the coast of Toulon,
France. The archaeological interest in this wreck is
considerable because only three wrecks of this type are known
and all had been robbed before being studied archaeologically.
A first campaign took place in October 2000 with the help of
COMEX who made available their exploration vessel Minibex,
their submarine REmora 2000 and a remotely operated vehicle
(ROV).
The principal objective of the October 2000 project was to
obtain digital photogrammetric coverage to record the actual
state of the wreck and to allow the creation of a site plan and a
3D reconstruction using simultaneously the observed data, and
archaeological sources and hypotheses.
6. THE SURVEY
An Etruscan amphora found on the Grand Ribaud F wreck, in
HyEres, France, was surveyed with combines mixed means of
Laser Scanner and photogrammetry measurement tools. The
survey took place at the University of Rome 111 in the laboratory
of architectural representation directed by Prof. Diego Maestri.
The survey phase can be divided in two main steps:
1) Laser scanner acquisition:
14 range scans were acquired with an horizontal step size
0,125ooand vertical step size of 0,25oo 13 range scans were
acquired from 13 different positions around the amphora,
maintaining the amphora in a fixed position through a tripod. 7
range scans were acquired using the laser scanner tripod
viewing the amphora top-down. 6 range scans were acquired
positioning the laser head on the ground viewing the amphora
from down to top. The range scan viewing the amphora inside
part was acquired positioning the object in different way. The
acquisition points were positioned with a maximum distance
from the amphora of about c.a. 2,7 m.
2) Photogrammetric acquisition:
A set of three photographs were taken, without too many
constraints, from each laser scanner positions and from 2 right
and left positions in order to guarantee a sufficient base-line. A
schematic view of the acquisition scheme is reported in
Figure 3.
Figure 3. Survey scheme.
7. DATA PROCESSING
7.1 Laser scanner data
After LFR data acquisition and storage the processing steps
listed in section 3.2 were performed.
During the pre-processing phase some manual work was
necessary in order to reduce noise problems especially on edge
area; due to the laser beam dimension some point are wrongly
measured were edges between object are present.
The standard method, based on Iterative Closest Point (ICP)
algorithm (Besl, McKay, 1992), was used for aligning each scan
in a single reference system (registration process) The a-priori
estimation of the relative position between two scans was
provided using some external reference points manually
recognized in the reflectance image.
In order to project the photos acquired centrally from the same
laser scanner position (see figure 3), the software needs to know
the external and internal camera parameters. Internal parameters
can be computed for a specific camera using standard computer