Spatial geodesy applications for accurate georeferencing of Soknopaiou Nesos site and DTM determination

Surveying procedures in Archaeology are often multidisciplinary techniques because they have to consider many aspects such as geometric description, documentation, stability, restoration, representation, virtual reality, etc (Bitelli, 2002). Nowadays a wide range of Geomatics instruments and procedures allows optimized surveys, every day refined and this progress is mainly related to various aspects such as: availability of efficient surveying instrumentation, advancement in computer science technologies and optimized field procedures. During the 2002 campaign conducted by the Joint Archaeological Mission of Bologna and Lecce Universities (directed by S. Pernigotti and M. Capasso, field director P. Davoli) at Dimai (Fayyum), the ancient town of Soknopaiou Nesos, several geodetic activities were carried out by the team of DISTART Dept., Engineering Faculty of Bologna University. The main purposes of the work were to provide an absolute high accuracy positioning, to generate the Digital Terrain Model (DTM) of the overall site and, finally, to realize a low-height aerial photogrammetric survey of the archaeological area. Concerning the surveys carried out on site, Global Positioning System (GPS) was extensively used, both for absolute positioning of reference stations and for accurate description of terrain surface. All the fieldwork made use of dual frequency geodetic GPS receivers and the activities carried out can be described into three main items: - long static observations to refer the local control points and the local surveys carried out by total station to the International Terrestrial Reference Frame via the International GPS Service (IGS); - GPS Kinematic survey of the Digital Terrain Model for the whole archaeological site; - measurements of Ground Control Points (GCPs) for low-height photogrammetric surveys carried out by a balloon based system developed by the authors.