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DETERMINATION OF OLD AND NEW DEFORMATIONS AT KUCUK AYA SOFYA 
(LITTLE HAGIA SOPHIA) MOSQUE IN ISTANBUL BY PHOTOGRAMMETRIC 
METHODS AND AN ATTEMPT OF THEIR INTERPRETATION 
A.Alkis 3 , E.G.Arun 3 , H.Demirel a, ,R.D.Diippe\ C.Gerstenecker b , M.Hovenbitzer c 
a Yildiz Technical University, Istanbul, Turkey (alkis, gorun, hdemirel )@yildiz.edu.tr 
b Darmstadt University of Technology, Germany, dueppe@gauss.phgr.verm.tu-darmstadt.de, gerstenecker@geod.tu-darmstadt.de 
c Federal Agency for Cartography and Geodesy, Germany, Hovenbitzer@ifag.de 
CIPA XIX ,h International Symposium Anatalya 2003 
KEY WORDS: Photogrammetry,Monitoring,Deformations,Documentation,Laserscanning,Visualization 
ABSTRACT: 
Scientists of Yildiz Technical University Istanbul and Darmstadt University of Technology have coorperated in order to collect and 
analyse different informations about the Kücük Aya Sofya Mosque (constructed between 527-536 A.D.) in Istanbul, one of the 
oldest and most important still existing buildings of byzantine era. The extraordinary beauty of the monument will be documented 
with a computer generated panoramic image of the indoors octagon. The great impact of the photographs to document how the 
building changed in time is shown by some examples. Furthermore the inclinations of the eight polygonal pillars in the central 
octagon and of the outer wall of the apse are determinated by photogrammetric methods. These inclinations are very large and 
generally very old, they might exist since the beginning of the building in the byzantine times of Justinian and his empress 
Theodora. But also present day deformations were found: there are a lot of cracks in the building. Some of them are controlled over 
a period of more than 20 years, especially the vertical cracks on the north-west and south-east corners of the dome. As a 
consequence the geometry of the whole dome was checked with photogrammetric methods, starting 1979 and ending 2002. The 
results of the deformation analysis are shown and discussed. In 2002 an in-and outdoor laser-scan of the complete building was 
performed. The results and further investigations are discussed. Additionally some of the damages resulting from the Izmit 1999 
earthquake (magnitude 7,4) are documented. 
KURZFASSUNG: 
Wissenschaftler der Yildiz Technischen Universität Istanbul und der Technischen Universität Darmstadt haben bei der Untersuchung 
der Kleinen Hagia Sophia (gebaut 527-536 A.D.) in Istanbul, einem der ältesten und bedeutendsten noch existierenden Gebäude aus 
der frühbyzantinischen Zeit, zusammengearbeitet. Die außerordentliche Schönheit des Gebäudes wird zu Beginn durch die 
Wiedergabe einer gerechneten Panoramaaufnahme des inneren oktagonalen Zentralraumes aufgezeigt. Dann wird an einigen 
Beispielen die Bedeutung vorhandener Photos für die Dokumentation des sich verändernden Geschehens aufgezeigt. Die 
Schiefstellungen der Pfeiler und einer Apsisaußenwand werden nachgewiesen, wobei die These vertreten wird, dass diese 
Schiefstellungen älteren Ursprungs sind, d.h. eventuell noch aus den Zeiten von Justinian und Theodora stammen. Aber auch neuere 
Deformationen werden präsentiert: einige der vielen vorhandenen Risse des Baus konnten photogrammetrisch über den Zeitraum 
1979-2002 beobachtet werden, gleiches gilt für die das zentrale Oktagon abschließende Kuppel. Die Ergebnisse werden diskutiert. 
Im Jahre 2002 wurde eine komplette Laserabtastung des Gebäudes durchgeführt, Ergebnisse und weitere notwendige Arbeiten 
werden besprochen. Zum Abschluß werden einige Schäden dokumentiert, welche durch das Izmit-Erdbeben (1999, Stärke 7,4 auf 
der Richterskala) neu entstanden sind. 
1. INTRODUCTION 
At Istanbul the church of Sergius-and-Bacchus (527-536 A.D.) 
or Little Hagia Sophia Mosque (Kiiciik Aya Sofya Mosque = 
KAM ) as it is called after the fall of Constantinople in the year 
1453 and after changing the church into a mosque (1504) 
belongs to the oldest and most important still existing buildings 
of early byzantine era. The KAM was commissioned by the 
roman Emperor Justinian and his Empress Theodora as an 
annex to the existing Peter-and-Paul-Basilica inside the palace 
of Hormisdas, the KAM survived in most of its parts, the Peter- 
and-Paul-Basilica doesn’t exist today any more. In spite of all 
its historical importance KAM is in a very poor condition 
today; we are convinced, that there is a real risk for the further 
existing of the building if nothing will be done for its 
restoration. Therefore the World Monuments Funds 
(www.wmf.org) has placed KAM into its list 2002 of the 100 
most endangered sites all over the world. Specialists of the 
Yildiz Technical University / Istanbul have worked at KAM the 
last years to collect informations in different disciplines [2,3]. 
In this context a mixed group of scientists of Yildiz and the 
Technical University Darmstadt / Germany have performed 
extensive geodetic and photogrammetric observations including 
a complete laserscan of KAM. The photogrammetric and 
geodetic measurements have started in 1979 and have been 
repeated several times till 2002. Therefore the team was able to 
investigate different problems as for example the fundamental 
question of the quality and quantity of the deformations which 
may endanger the near future of the KAM. To understand some 
of the problems, let’s have a first look at KAM: an octagonal