THE 3D SURVEY OF THE ROMAN BRIDGE OF SAN LORENZO IN PADOVA (ITALY): A COMPARISON BETWEEN SFM AND TLS METHODOLOGIES APPLIED TO THE ARCH STRUCTURE
3D survey methodologies are widely applied to the Cultural Heritage, employing both TLS and close-range photogrammetry with SfM techniques. Laser scanning produces models with high metric reliability and accuracy, whereas the main quality of the 3D photogrammetry is the result in term of photorealistic representation. Many studies have been conducted about the comparison and the integration of these different approaches and the aim of this paper is to contribute with a peculiar case study: the underground Roman bridge of San Lorenzo in Padova (Italy). The investigation regards the resulting point clouds of the intrados (or inner curve) of the central arch, comparing them and providing graphical and analytical outputs. The proposed workflow has the purpose to be a simple but valid tool to detect and evaluate geometrical differences, their significativity and the reliability of the 3D models.