Il rilievo delle superfici tramite fotogrammetria 3D: dal microscavo dei complessi tombali agli scavi in open area

The need for a quick methodology of 3D surface recording, sensitive to the timing of fieldwork, low cost, and suitable for both micro- and meso-contexts, has induced the writers to develop a standard procedure. It is now possible to obtain a dense x, y, z point cloud starting from the photographic coverage of a surface, respecting precise parameters of overlapping for the different photos picturing the scene, and calibrating the camera. The software used to generate the point cloud is PhotoModeler Scanner, chosen firstly for its internal module of camera calibration and correction algorithm of radial distortion, and secondly for its capacity to verify the position of the different frames and point clouds roto-translating in a known reference system. The key point of the procedure is the importing of the point cloud in a GIS environment, where a DEM is created with an interpolation algorithm. The resulting surface is in the same GIS environment of vector and raster themes documenting the excavation. The procedure was tested in two different case studies: a micro-context corresponding to Tomb 112, a cremation tomb in the Iron Age necropolis of Piovego (Padua, Italy), and a meso-context corresponding to the Late Bronze Age settlement of Gradiscje (Codroipo, Italy). In both cases, meaningful because different in scale stratigraphy and survey issues, it is clear how 3D survey and the subsequent modeling of the point cloud has been fundamental for the understanding of the archaeological record.