The church of San Carlo dei Barnabiti houses one of the most important examples of Baroque illusionistic painting in Florence. <br><br> Given the level of deterioration of the vault, the preliminary investigations required a 3D survey of the current geometry to detect the mainly damaged areas. A point cloud obtained by laser scanning is employed to investigate the deformations and the state of conservation of the vault. The acquired data also revealed some unknown aspects concerning the construction of the structure and its pictorial decoration useful to design the restoration project.