DIGITALLY DEVELOPING WORKS OF ART 
Andreas Georgopoulos (l) , Charalabos Ioannidis (2) , G. Makris (3) , 
E. Tournas (4) , Sevasti Tapinaki ,4) 
(1) Professor, Dept, of Rural and Surveying Engineering, Lab. of Photogrammetry, National Technical University of Athens 9 Iroon 
Polytechniou st., GR-15780 Athens, Greece 
Phone: +3017722675, fax: +3017722677, e-mail: drag@central.ntua.gr 
<2) Assistant Professor, Dept, of Rural and Surveying Engineering, Lab. of Photogrammetry, NTUA, Greece 
Phone: +3017722686, fax: +3017722677, e-mail: cioannid@survey.ntua.gr 
(3) Assistant, Dept, of Rural and Surveying Engineering, Lab. of Photogrammetry, NTUA, Greece 
<4) Researcher, Dept, of Rural and Surveying Engineering, Lab. of Photogrammetry, NTUA, Greece 
KEY WORDS: Digital Images, Large Scale, Mosaics, Curved Surfaces 
ABSTRACT 
During a strong earthquake two years ago, the Byzantine Monastery of Daphni in Athens suffered severe damages. This particular 
monument is considered one of the most important specimens of Byzantine art and architecture worldwide. 
For the purposes of detailed archaeological and artistic research, the recording of the magnificent mosaics of the main church 
(Katholikon) at a very large scale was considered necessary. The problems of recording such works of art at a scale of 1:5 are 
numerous. However the requirements included, among others, the raster development of those mosaics which are constructed on 
developable, i.e. cylindrical or conical, surfaces. 
In this paper all considerations for this task are presented and their implementation is described in detail. The issue of the reference 
systems combination is firstly addressed. Secondly the problem of suitably performing the stereoscopic photography is also 
considered. Finally the required photogrammetric measurements are performed on a digital photogrammetric workstation. 
For this task specialized software has been developed in order to accommodate for the data acquired during the surveying process. 
Several examples of the resulting digital raster files are also discussed and assessed for their usefulness and accuracy. 
1. INTRODUCTION 
The Dafni Monastery is one of the two remaining today excellent specimens of the culmination of Byzantine architecture (Figure 1). 
It was built in the 11 th century and is situated in the southeastern part of Attica near Athens. The whole monastery extends on an area 
of 0.7 hectars and in the centre of that area lies the majestic central church, the Katholikon. In essence it is a cross-domed octagon 
type of church extending approximately 25x15 m 2 and 20 in height. The Monastery is considered to be the Parthenon of the 
Byzantine era and is internationally protected by UNESCO. 
Figure 1 : The Dafni Monastery 
The strong earthquake of 7 th September 1999 caused severe damage to the Katholikon and the rest of the buildings of the monastery. 
The Ministry of Culture immediately decided to take strong measures in order to protect the monument. Before any static or 
structural interventions a thorough survey of the monument at a general scale of 1:25 was decided. The Laboratory of 
Photogrammetry of NTUA undertook this task. 
Proceedings 18 th International Symposium CIPA 2001 
Potsdam (Germany), September 18 - 21, 2001