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DOCUMENTATION AND VISUALIZATION OF HISTORICAL CITY CENTERS: 
A MULTI-SENSOR APPROACH FOR A NEW TECHNOLOGICAL PARADIGM 
P. Patias, G. Karapostolou, P. Simeonidis 
Department of Cadastre, Photogrammetry and Cartography, The Aristotle University of Thessaloniki, Greece 
patias@topo.auth.gr 
WG V/4 
KEY WORDS: Heritage documentation, Visualization, 3D modelling, Information management 
ABSTRACT : 
The development and functionality of a 3D modelling, visualization and Information management system for the historic center of 
Thessaloniki is presented. 
The main idea is the use of both aerial and close-range imaging for constructing Digital Elevation Model, Digital Surface Model (that 
is building hights), 3D drapping of orthophoto, 3D recontructions of the historically important buildings of the city center, close- 
range images of building facades, rectification and drapping on those images on the facades, and video sequence of both real and 
virtual "historic walks". 
Control points are extracted from the aerial images and used in facade reconstructions. Additionaly, databases are constructed with 
historical information about the buildings. These databases are linked with the 3D graphic files into an Internet-based Information 
System. Real examples are given from the historical center of Thessaloniki, where more than 200 buildings have already been 
documented and inserted into the system for GIS exploration and visualization. 
1. RATIONALE, MOTIVATION AND AIM 
According to the ICOMOS report on “Principles for the 
Recording of Monuments, Groups of Buildings and Sites” 
[URL1] : "As the cultural heritage is a unique expression of 
human achievement; and as this cultural heritage is 
continuously at risk; and as recording is one of the principal 
ways available to give meaning, understanding, definition and 
recognition of the values of the cultural heritage; and as the 
responsibility for conserving and maintaining the cultural 
heritage rests not only with the owners but also with 
conservation specialists and the professionals, managers, 
politicians and administrators working at all levels of 
government, and with the public; and as article 16 of the 
Charter of Venice requires, it is essential that responsible 
organizations and individuals record the nature of the cultural 
heritage." 
While, article 16 of the Venice Charter [URL2] requires that "In 
all works of preservation, restoration or excavation, there 
should always be precise documentation in the form of 
analytical and critical reports, illustrated with drawings and 
photographs. Every stage of the work of clearing, 
consolidation, rearrangement and integration, as well as 
technical and formal features identified during the course of the 
work, should be included. This record should be placed in the 
archives of a public institution and made available to research 
workers." 
Accordingly, the ICOMOS Charter for the Conservation of 
Historic Towns and Urban Areas [URL3] defines that the 
qualities to be preserved include “...the historic character of 
the town or urban area and all those material and spiritual 
elements that express this character, especially: 
® urban patterns as defined by lots and streets; 
* relationships between buildings and green and open 
Spaces; 
e (he formal appearance, interior and exterior, of buildings 
as defined by scale, size, style, construction, materials, 
colour and decoration; 
e [he relationship between the town or urban area and its 
surrounding setting, both natural and man-made; 
e the various functions that the town or urban area has 
acquired over time. 
Any threat to these qualities would compromise the authenticity 
of the historic town or urban area.” 
Later, the same document states "The participation and the 
involvement of the residents are essential for the success of the 
conservation program and should be encouraged. The 
conservation of historic towns and urban areas concerns their 
residents first of all.” 
Therefore, the recording of the cultural heritage is essential: 
e to acquire knowledge in order to advance the 
understanding of cultural heritage, its values and its 
evolution; 
e to promote the interest and involvement of the people in 
the preservation of the heritage through the dissemination 
of recorded information; 
e to permit informed management and control of 
construction works and of all change to the cultural 
heritage; 
e to ensure that the maintenance and conservation of the 
heritage is sensitive to its physical form, its materials, 
construction, and its historical and cultural significance. 
Moreover, the recording should be undertaken to an appropriate 
level of detail in order to: 
e provide information for the process of identification, 
understanding, interpretation and presentation of the 
heritage, and to promote the involvement of the public; 
—393—