Calibrating and evaluating a range camera for Cultural Heritage metric survey

At the last ISPRS Congress in 2008, the first experimental evaluations of range cameras were presented. During the last four years, much research has been done by different research groups and some meetings have allowed a continuous sharing of experiences and results. The research group of the Politecnico di Torino has developed some original methodologies for calibrating range cameras and a set of tests for evaluating the possible use of range cameras for Cultural Heritage metric surveys. Cultural Heritage objects are characterized by complex shapes and different materials (e.g. stones, plasters, etc.). The present paper describes the results achieved in calibrating the SR4000 range camera and it studies the influences of the measuring direction inclination and of the different materials on distance measurements accuracy and completeness. This allows defining which are the possible strategies to be adopted to give affordable and useful point clouds for the metric description of Cultural Heritage objects. Some basic metric survey examples of architectural objects are given to demonstrate the real application of such devices to Cultural Heritage metric documentation, from the acquisition of point clouds up to 2D (elevations) and 3D representations (texturized 3D models). Considering the current development of such devices and their possible future evolutions, the expected possible uses of range cameras in Cultural Heritage metric survey should be advantageous, especially considering the low costs of such devices and the possibility of their making 3D videos which can be acquired in a short time.