Development of a 3D Information System for the Old City Centre of Athens

The representation of three dimensional city models has been gaining ground increasingly in many scientific fields in the recent years. 3D City Modelling is a scale representation of natural and artificial objects in order to present the spatial data and highlight the social development of the city. Depending on its importance or the purpose of use, an object can be represented in various levels of detail. An increasing tendency to 3D city models is their integration into GIS, which proves to be an effective tool for managing, analyzing and planning in order to make decisions about technical, administrative and financial matters. A combination of digital photogrammetric techniques and laser scanning data contribute greatly to this, since a variety of data, such as aerial, satellite and terrestrial images, point clouds from airborne and terrestrial laser systems, and also a variety of photogrammetric and mobile mapping methods are available. The objective of this paper is the development of a 3D Information System (IS) for the three-dimensional geometric documentation of the buildings owned by the Ministry of Culture in the old city centre of Athens, Greece, named “Plaka”. The area has been inhabited continuously since the prehistoric era, it has a special architectural style and includes a number of unique cultural heritage monuments. The data used for the reconstruction of the 3D model of Plaka consisted of aerial and terrestrial images, while raster, vector and descriptive data were used for the creation of a 2D GIS, which served as the background for the development of the 3D GIS. The latter includes all of the qualitative and quantitative information related to the 3D building models owned by the Ministry of Culture according to users’ needs. Each building in the vicinity of Plaka was depicted in one of the four different levels of detail created for the purpose of the study, according to their ownership status and other criteria. The building models, depicted in the highest level of detail, were owned by the Greek Ministry of Culture whereas the other buildings (of a lower level of detail) were depicted in a more subtractive way. Therefor an integrated IS was developed that combines descriptive information, e.g., use, legal status, images, drawings, etc, with the spatial information and geometric documentation in three dimensions