UAV and RPV systems for photogrammetric surveys in archaelogical areas: two tests in the Piedmont region (Italy)

Aerial photogrammetric surveys are usually expensive and the resolution of the acquired images is often limited. For this reason, different innovative systems have been developed and tested in order to perform a photogrammetric survey in an inexpensive way, with high-resolution images. In this context, one of the most promising acquisition techniques is represented by the use of Unmanned Aerial Vehicles (UAVs) equipped with a digital camera.The paper deals with the acquisition and processing of low-height aerial imagery acquired by UAVs and Remote Piloted Vehicles (RPVs), in order to provide large-scale mapping to support archaeological studies: the pros and cons of these acquisition platforms are presented and discussed. These systems carry out flights that are usually very different from the manned systems as their dimensions and their light weights never allow the set course to be flown; for this reason, the acquired images are often affected by large rotations and small overlaps. Therefore, an ad hoc procedure has been implemented to overcome these limits. In this work, two remote-controlled systems (a mini-helicopter and a mini fixed-wing plane) were tested over two different archaeological sites in order to provide Digital Surface Models (DSMs) and large-scale maps (numeric maps and orthophotos). Finally, an accuracy evaluation of the final products is reported.

Research highlights
► UAVs.
► Multi-image matching techniques.
► Orthophoto generation for archaeological survey and documentation.