Geometry and reflectance acquisition for physically-based rendering applied to interactive 3D visualization of cultural heritage.

The present work deals with the geometry and reflectance acquisition of physical objects, especially those belonging to cultural heritage. The development of these technologies has been limited to a few research groups, since they demand not only advanced technical knowledge, but also abundant financial resources. In this context, the objective of the present work was to develop a system for the documentation of the complete appearance of cultural heritage artifacts, applying accessible geometry and reflectance acquisition strategies, and texturing tools for physically-based rendering. The study was successful in developing an automated prototype of said acquisition system. The separation of diffuse and specular reflectance components was implemented using cross polarization of light, and the geometry is obtained through photogrammetric reconstruction. The study verified the effects of variable sampling density on the geometric and reflectance reconstruction. The reconstructed 3D models were submitted to dimensional deviation tests, and, based on additional processing time measurements, it was possible to outline guidelines for the selection of efficient reconstruction parameters. The visual products obtained with the proposed method were, finally, compared to scans carried out without considering the reflectance behavior, for which short-range photogrammetry and an Artec Eva scanner were used. Comparative analysis showed improvements in the quality and accuracy of the digital representation of scanned artifacts, provided by the additional reflectance acquisition and physically-based rendering. The proposed method, therefore, proved to be an efficient and feasible alternative for documenting the complete appearance of cultural heritage, being also suited for other fields.