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

656
PHOTOGRAMMETRY IN EPHESOS - RECORDING BASIC SPATIAL DATA
Stefan KLOTZ
Austrian Archaeological Institute
A-1190 Vienna, Franz Klein-Gasse 1
AUSTRIA
Email: Stefan.Klotz@univie.ac.at
The presented project is a co-operation of the Department of Photogrammetry (TU Istanbul), the Institute of
Photogrammetry and Remote Sensing (TU Vienna) and the Austrian Archaeological Institute (Vienna).
KEY WORDS: Photogrammetry, Cultural Heritage, Archaeology, GIS, Orthoimage
ABSTRACT:
Ephesos, on the west coast of Turkey, has been one of the most important cities of the Roman empire. Here, Austrian archaeologists
carry out research and excavation for more than a hundred years. The first and the last comprehensive geodetic surveying of the
whole area of Ephesos dates back to the very beginning of the Austrian activities. Aim of the current project is to obtain a valid
mapping of the region of ancient Ephesos with the neighbouring sanctuary of Artemis. Seven infrared aerial photographs form the
fundamentals of the photogrammetric process. Contoureline, inclination and shaded relief maps were derived from a terrain model
and research work done into ancient water conduits. A Mosaic-Orthophoto was generated from the arial images with help of the
terrain model. This map, together with the revised photogrammetric line analysis and the city plan, the latter generalised for a scale
1:5000, have been united in a GIS.
1. INTRODUCTION
Ephesos, on the west coast of Turkey, was one of the most
important cities of the Roman Empire. Here, Austrian
archaeologists have been carrying out research and excavation
for more than a hundred years. The first and the last
comprehensive geodetic survey of the whole area of Ephesos
dates back to the very beginning of the Austrian activities
(Schindler, 1906).
Aim of the current project is to obtain a valid mapping of the
region of ancient Ephesos including the neighbouring sanctuary
of Artemis. Drawing up a digital terrain model, an orthophoto
as well as a cartographic map are the pursued goals. A digital
plan of the ancient city, generated by means of digitised plans
and new surveying, was already available at the start of the
project.
In the following, the possibities and applications offert by
spatial data will be shown at the example of Ephesos.
2. ORIGINAL MATERIAL AND PRECONDITIONS
Seven infrared aerial photographs taken in 1997 form the basic
material of the photogrammetric process. The arial photographs
were taken by Turkish authorities on the occasion of an
inspection flight regarding the amount of standing timber:
• aerial photograph format: 23 x 23 cm
• imagescale: 1:15000
• year of flight: 1997
The stereographically evaluated model area covers a surface of
approx. 32 km2. The details were interpretated in an area of
18.4 km2, which includes the urban area of Ephesos with its
city walls, the sanctuary of Artemis and the Ayasoluk with St.
John’s Church and the castle.
Due to this special purpose the photographs do not provide any
geodetically measured controlpoints signalised in the course of
the flight. For analysis it was therefore necessary to select
natural controlpoints in the pictures, characteristics such as
edges of roofs, traffic-line markings etc. were used, which then
had been measured in the field by GPS (Global Positioning
System). Therefore it was possible to implement the aerial
photos in the Ephesos Referenence Frame 1998 (ERF98) in
which all other surveying in Ephesos is made. The ERF98 is
defined by the global reference frame (ITRF94). Measurements
for the bundle adjustment as well as the entire further mapping
were undertaken with an analytic plotter. Following the bundle
adjustment a medium standard deviation of ±18 cm at position
and ±25 cm at height (internal accuracy) resulted for the tie
points (points visible in two or more photographs but without
ground control).
3. DATA AND ANALYSIS
In the course of stereographic analysis the whole visible
situation (vegetation, traffic zones, buildings, waters, etc.) was
measured. In order to create a digital terrain model (DTM), a
point grid by 20 x 20 m resp. 80 x 80 m (varies due to the
character of the ground) as well as breaklines were measured.
So a very detailed recording of the terrain structure was
achieved. Apart from photogrammetric regular points and
breaklines, terrestrial as well as GPS surveyed points and
breaklines were also involved in order to gain the digital terrain
model. This procedere proceeding a substantially increased the
accuracy, especially for areas in close neighbourhood to
archaeological sites. Finally, about 80 000 points were used to
derive the DTM..
4. ORTHOPHOTO MAP
Four orthophotos were generated from the aerial photographs
with the help of the new terrain model. Then, these orthophotos
were combined to one single orthophoto map (Figure 1). The
resolution of the digital orthophotos is limited by the scale of