Transportable 3d Acquisition Systems for Cultural Heritage. Reverse Engineering and Rapid Prototyping of the Bronze Lions of the Saint Isidoro Chapel in the Basilica of San Marco in Venice

This research illustrates the experimentations accomplished in the field of Cultural Heritage aimed to the determination of the “total form” of the objects with a high resolution, using a simple and transportable acquisition technology. The aim of this research is to identify the process and the methodology for the acquisition of geometric information of three-dimensional objects which are situated in area that can be reached with a great difficulty. In some cases the traditional laser scanner equipments can’t be used in the lack of visibility, of space and on instable surfaces. Transporting in an easy way a small equipment can become an operational advantage that can’t be ignored in term of costs. This study puts together various advanced experiences from different fields and reverts them for the field of Cultural Heritage to obtain an approach methodology for the study of the “total form”. The objects of our experimental applications are some bronze sculptures collocated in the chapel of Saint Isodoro in the Basilica of Venice. The operational phase of this project has interested the Politecnico of Milan and the Procuratoria di San Marco in Venice. In the actual state, has been acquired high resolution scan (0.2mm) of the both sculptures of the bronze lions with the portable system HandyScan 3D and the elaborations have been realized with VxScan and Rapidform Xo-Scan. The scanning system requires reference targets which have been situated on the interesting surface with a grid patch that various from 20 to max 100mm. These targets let the instrument to self-determinate its own position in the space doing in the real time a space resection on at least three targets. In addition to the spatial position of the points during the acquisition, is also automatically generated the mesh of the surface. The phase of acquisition ends writing the points or meshed files for examples in the standard .stl format.