CIPA 2003 XLX"‘ International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
385
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Upon the completion of excavation work on October 4 th 2000,
evaluation, documentation, computer entry and storage
arrangement works were started at the excavation center. Five
experts from the Turkish team taking part in excavation work
continued with the classification, drawing, photographing,
documenting and reporting on hundreds of thousands of clay
bulla and coins. This team was also engaged in the follow up of
new finds emerging as a result of changes in the level of water
and waves and in ensuring the coordination with other teams.
Turkish teams in the urgent excavation and rescue also
conducted their work in a very tidy manner.
3.3 Open-air Museum
In order to minimize the adverse effects of dam constructions on
people, their economic means as well as on cultural properties,
studies and surveys to this end had been started in 1992. Later,
the findings of these studies and surveys were gathered in action
plans and implementation.
Projects relative to the protection of cultural properties in the
region are addressed under the "Project Package for the
Protection of Cultural Properties" and they are given priority in
the annual programs of the Administration. Within this scope, it
is planned to establish an open-air museum in order to exhibit
all finds of Zeugma in-situ. Since the excavations at Zone C will
continue, this plan could be implemented step by step at the
areas that the excavations are completed.
4. REMOTE SENSING AND PHOTOGRAMMETRIC
ISSUES
Location is an important issue for the management of
archeological sites. It has vital importance during both planning
and operational phases. If the location of a site is unknown, it is
naturally impossible to take any action to manage, preserve or
protect the site and its belongings. Determination and
presentation of information related to location is accomplished
via mapping of the site
Taking into consideration that the up-to-date small scale
topographic maps (1:25K to 1:250K) of the area are available
both in printed and raster forms, new map production should
cover the large scale maps 1:500 or 1:1000 and 1:5000 for
archeological excavations that will be carried on and detailed
planning purposes respectively.
4.1 Ground Survey
Ground surveys that should be conducted will be mainly GPS
observations on pre-selected ground control points (GCP) in
order to determine the exterior orientation parameters of
airborne sensors. Proper marking of the points that are observed
is necessary so that they can be clearly identified on the image.
Conducting a leveling work to determine the orthometric
heights of the GCPs is optional since the geoid heights that are
needed to derive the orthometric heights from GPS observations
is known to +/- 10 cm accuracy. Nevertheless, by conducting
first order leveling to 1 or 2 GCP will upgrade the height
accuracy to +/- 5 cm.
In order to determine the coordinates of the GCPs with cm
accuracy, at least one of the two points of Turkish National
Fundamental GPS Network (TUTGA) points, which are very
near to the area, should be used during the GPS observation
campaigns, where TUTGA is established by General Command
of Mapping and comprised of 594 points (Figure 2).
Figure 2. Turkish National Fundamental GPS Network.
Kinematic GPS supported aerial photography, by which
projection center coordinates of each photo is obtained, reduces
the number of ground control points at a considerable amount.
Technique mainly depends on simultaneous operation of at least
two GPS receivers, one on board in connection with the camera
recording the time tag of the camera exposure instance, and the
other(s) on the ground, preferably on a well-defined geodetic
network point(s). At the end of the flight, GPS data, collected
both on the flight and the ground, are processed to determine the
projection center coordinates of the photograph at the moment
of imaging. For a combined bundle block adjustment with
projection center coordinates determined by relative kinematic
GPS-positioning, control points are required only in the block
comers if the flight lines do not exceed 30 base length
(Jacobsen 1996).
On the other hand, in case the direct georeferencing of the
airborne sensor could be made possible by operating a
GPS/IMU, then theoretically there would be no need to conduct
a ground survey. IMU is the acronym for Inertial Measurement
Unit, which is derivative of Inertial Navigation System (INS).
Within the last years numerous tests were conducted in order to
determine the accuracy of integrated GPS/IMU for direct
georeferencing, which was shown to be a serious alternative to
indirect image orientation using classical or GPS-supported
aerial triangulation. Since direct georeferencing without ground
control relies on an extrapolation process only, remaining errors
in the system calibration will significantly decrease the quality
of object point determination (Cramer et al 2002).
4.2 Image Acquisition
Image of the area can be acquired either from airborne or
spacebome sensors. In case of airborne imaging, flight should
be conducted at two different altitudes to obtain 1:4000 and
1:16000 scale aerial photography for 1:500 or 1:1000 and
1:5000 scale map production respectively.
At the moment Quickbird and Ikonos are the satellites to collect
the highest resolution of imagery commercially available. It is
stated that Quickbird panchromatic or natural color imagery of
60 to 70 cm resolution depending on the off-nadir angle is
capable of supporting mapping in the 1:2500 to 1:5000 scale
range (Nale 2002). On the other hand, accuracy assessments of
the 1 m resolution Ikonos panchromatic imagery have been
revealed that mapping accuracy achieved is about 2 m and it
could be upgraded towards 1 m by improving the accuracy of
the GCP (Fraser et al 2001, Grodecki et al 2001, Toutin 2001).
As a matter of fact, the information contents of the Ikonos
panchromatic images correspond to 1:10000 scale topographic
maps (Jacobsen 2002b).
