UAS proximal remote sensing for complex ancient quarries 3D documentation

The documentation of ancient quarries is often very critical due to the complexity of the archaeological sites. In this paper we discuss a method based on proximal sensing photogrammetry technique, to obtain detailed survey by means of an Unmanned Aerial Systems (UAS). This technique allows to acquire high definition digital images to generate, by means of semi-automatic photogrammetric algorithms, very dense point clouds and Digital Surface Model. The method based on UAS platforms allows to perform survey also in hazardous areas with reliability and safety, in order to obtain metrological data from 3D reconstruction of quarry sites. The proximal sensing survey was performed at different flight heights, according to the ground sample distance (GSD) needed to generate DSM by the combination of different photogrammetric shots at consistent resolutions. The flight planning is another very important step, that must consider steep or tall quarry walls and t5he variable exposition to the incident light, in order to minimize the errors on digital models and to obtain more detailed representation. This method allows to investigate on stone exploitation technology, volumes of the materials exploited and debris accumulation, geometrical and dimensional characteristics of the stone artefacts production. With approach we can also evaluate the archaeological heritage interactions with the environmental processes, as support of conservative and valorization projects.