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New perspectives to save cultural heritage
Altan, M. Orhan

Z. Duran, G. Toz
ITU, Civil Engineering Faculty, 34469 Maslak Istanbul, Turkey - (duranza, tozg,)@itu.edu.tr
KEY WORDS: Photogrammetry, Cultural heritage, Documentation, Reconstruction, Visualization, GPS, Modeling, Virtual reality
The land of present-day Turkey, stretching out between Asia and Europe, has been called the crossroads of history. It has always
been the scene of international exchange of culture, art and architecture. Since early days, the traditions of the past, in the social and
cultural reflection of various Anatolian Civilizations can still be seen in Turkey and in the remains of historical cities dating from the
Neolithic and Early Chalcolithic Ages to mosques, palaces and historical houses of the Ottoman Period.
With are timber houses and winding streets, Fatih is a typical region of old Istanbul. As in most other areas of old Istanbul, fires have
caused much devastation in Fatih. The monastery of Christ Pantepoptes (Eski Imaret-i Atik Cami) in Fatih was selected to sample
building for the case study.
The recording and documentation of the monastery of Christ Pantepoptes (Eski Imaret-i Atik Cami) has been realized by a
combination of state-of-the-art technology: GPS measurements and tacheometry have been applied as well as photogrammetric
Several methods of visualization have been applied to the data set. Besides the rendering of the photo realistic images with high
resolution, video films have been produced and interactive inspection in a virtual reality environment has been derived.
Architecture is a substantial part of our cultural heritage. But
whereas other elements of our cultural heritage may be
protected by putting them behind a glass in a museum,
architectural monuments are widely used and endangered by
long term influences like traffic or air pollution or destructive
events causing heavy damage like earthquakes, fire or war etc.
But by all means when monuments are seriously damaged, or
completely destroyed, the amount and quality of any surviving
documentation becomes highly important.
Therefore it is necessary to document the actual state of the
architectural monuments in a manner, which opens the
opportunity to detect continuous damage by change detection
techniques and to restore the monument in case of heavy
damage. Before starting to acquire new data on the monument
already existing data sources have to be obtained, e.g. existing
plans of previous restorations, ancient pictures or
documentation's of architectural research projects.
The 3D reconstruction of buildings has been an active research
topic in Computer Vision as well as in Digital Photogrammetry
in recent years. Three-dimensional building models are
increasingly necessary for urban planning, tourism, etc. (Suveg
and Vosselman, 2000).
Three-dimensional photo-models help us to understand spatial
objects, even if they are not accessible for us. Using photo
models from existing objects can make it easier for us to
understand complex spatial structures. With the help of
methods coming from virtual reality we can link additional
information in the form of text or sound sequences to our photo
models. An architect, for example, can generate an interactive
three-dimensional information system based on a photo-model,
which describes and visualizes an important building [Dorffner
and Forkert, 1998].
Visualization efforts in Photogrammetry do not have a long
history. In the beginning of 90’s the first photogrammetric
attempts were mainly focused on the use of CAD software and
the generic visualization tools they had to offer. Most of the
research efforts at that time were concentrated to automating the
data acquisition and processing through Digital
Photogrammetry concepts, thus little attention was paid on how
to add value to the data.
A three-dimensional photo-model is an object model where the
texture information is taken from photographs or other optically
working recording systems. It consists of two parts. One part is
the three-dimensional object model in which the shape of the
object surface is stored. Adjoining surface patches approximates
the object itself. The second part is the photo-texture, which is
transformed to the patches (Dorffner and Forkert, 1998).
To visualize the derived model the photogrammetric data are
converted to VRML (Virtual Reality Modeling Language).
VRML is a format for 3D data with features like hierarchical
transformations, light sources, viewpoints, geometry, animation,
fog, material properties and texture mapping (Carey and Bell,
1997). VRML is an open format that has become popular
because of its suitability for publishing 3D data on the World
Wide Web. For this reason there is a lot of software available
that can handle VRML. This software allows a user-friendly
interactive examination and visualization of the data. The
conversion to VRML is fully automatic and consists of two
parts: geometry conversion and texture mapping. In the
geometric part the object coordinates and the topology
information are converted. [Heuvel, 1998].