Tecniche digitali e di visualizzazione in geoarcheologia: il caso di studio della terramara S. Rosa di Poviglio (Re)

Mauro Cremaschi, Andrea Ferretti, Maurizio Forte

«Archeologia e Calcolatori» 1994, 5, 305-316

Abstract

S. Rosa terramara, which measures 7 hectares, is a Middle and Recent Bronze age site, excavated since 1984. Cooperation between archaeologists and geologists has made it possible to experiment with the comparative analysis of computer image processing of the aerial photos, integrated with the detailed study of a DTM (Digital Terrain Model), in particular in relation to the geopedological and geoarchaeological interpretation of the site. The integration of two kinds of data, aerial photographs and a DTM, has been complemented by the texture mapping of the aerial photo overlaid on the corresponding 3D model. Significant ranges in the pixel distribution in the digital aerial image identified four main areas; any area presents particular digital features. For example, the digital features of the small village are very different from the characteristics of the large and more recent village. The digital classification of these areas identified the following: area 1, alluvial sediment (posthumous) which hides part of the earthwork; area 2, the nucleus of the small village; area 3, the diking of the big village; area 4, a Roman villa (another posthumous event). The final interpretation, after processing, distinctly shows the formation of natural (vertisoils) and artificial deposits (earthworks). In particular in the north-western area of the aerial photograph the interruption of the diking means that in that point the structures are buried because of a flood. Moreover, it results that the two villages are separated by a large ditch. On the basis of these results it has been possible to reconstruct the evolution of the site and of the environment in different periods: 1) the site before the Bronze age; 2) the terramara in the Middle Bronze age; 3) the terramara in the Recent Bronze age; 4) the site in Roman age; 5) the site in Medieval age. The computer processing, integrated with the aerial photo-interpretation, shows an important series of data not obtainable through traditional techniques. The construction of the DTM, the texture mapping and the digital image processing have clearly enhanced the shape of the structures of the terramara as well as the stratigraphical excavations. This also resolves the problems which emerged in the aerial photo interpretation. In particular, the interruption of the earthwork of the big village in the northern area seems connected with the burial of part of the anthropic structures, after the abandonment of the terramara. In conclusion, the computer image processing, together with the DTM and the texture mapping of the site, is an exportable tool, useful for an evaluation of the state of preservation of the Bronze age deposits in the Po valley. These results were obtained without excavation, using only simple stratigraphical surveys on the ground.

Figures

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