UAV oblique photogrammetry and lidar data acquisition for 3D documentation of the Hercules Fountain

This paper discusses some enhancements concerning 3D modelling, and the integration and comparison of 3D data from aerial and terrestrial sensors, developed by innovative geomatics techniques around the metric documentation of cultural heritage. In archaeology, it is interesting to deal with the considerable advantages of new multi-sensor approaches for the data acquisition and the management phases in terms of the sustainability (automated acquisition, quickness, precision, time and cost cutting). In particular, Unmanned Aerial Vehicles(UAVs)photogrammetry with the joint use of nadir and oblique cameras can be usefully combined with the large-scale details acquired by the terrestrial Light Detection and Ranging (LiDAR)in vast areas or complex objects, especially in mostly vertical sized objects. Here, we will report the results of an integrated 3D survey in an archaeological context in the Piedmont region of Italy. The Hercules Fountain is located in the gardens of the Venaria Reale (a Savoy Royal Palace included in the UNESCO heritage list) and has witnessed several events and historical phases during the past centuries–from its construction in the 16thcentury to its disuse and decline in the 17thcentury, right up to the 21stcentury when it was eventually brought back to light. The goal of the test is the creation of a3D continuous model of the site for documentation purposes, future consolidation, and enhancement projects finalised fora public promotion. To meet these strategic aims, a terrestrial laser scanning (TLS henceforth) survey has been designed together with multi-flights by a multi-rotor UAV and terrestrial close-range photogrammetry (CRP) acquisition to produce a highly detailed 3D textured model from which we have inferred standard 2D drawings, digital orthoimages, and further 3D products. In conclusion, the entire workflow and the outputs have been compared together to evaluate the effectiveness of each elaboration according to the different goals of the survey.