From Optical Acquisition to Rapid Prototyping: Applications to Medicine and to Cultural Heritage

Abstract

In addition to CAD techniques currently used to produce a 3D model of an artifact for subsequent prototyping, 3D acquisition by means of optical digitizers is dramatically growing as a powerful companion of rapid prototyping, for the creation of prototypes from existing objects such as maquettes, sculptures and body parts. The availability of a large amount of 3D acquisition systems on the market, both based on lasers and on incoherent light, greatly facilitates the process. In general terms, a reconstruction process is based on the steps of (i) acquisition, (ii) point cloud elaboration, (iii) mesh generation, (iv) STL (or equivalent) file generation, and finally (v) prototyping. Our Laboratory has been involved for years in the development and use of 3D scanners. The aim of this chapter is to illustrate the pathway from the object under interest to the prototype. We will present the main results of the research carried out in the fields of maxillofacial reconstruction, forensic medicine and cultural heritage, using optical 3D range sensors (3DS), reverse engineering (RE) and rapid prototyping (RP) techniques. The first activity originated from a request of our University dentistry specialists, in 2007. The aim was to develop the procedure for producing facial prosthetic elements able to reduce the patient’s discomfort and the dependence on the anaplasthologist skill, and to increase the process efficiency and performance. The second activity originated from a request of the Italian State Police in 2004. The goal was to assess the feasibility of using contactless sensors to (i) document crime scenes before their removal, and (ii) measure lesions on cadavers in post mortem analysis. The third activity has been carried out since 2001 upon request of archaeologists interested in studying, monitoring and reproducing pieces of cultural interest. Over the years, we have accumulated a remarkable experience in these fields. On one hand, we have been helped by the experience previously accumulated at the Laboratory in the frame of 3DS, RE and RP, especially in applications typical of mechanical, manufacturing and automotive industry (Sansoni & Docchio, 2004; Sansoni & Docchio, 2005). On the other hand, we were excited by the opportunity of exploiting our experience even in fields far from industrial production, such as those mentioned above. Although 3DS, RE and RP methods are well known in production fields, their experimentation in the applications of interest here is recent. In maxillo-facial prosthetic