LiDAR RTK Unmanned Aerial Vehicles for security purposes

Unmanned aerial vehicles (UAVs) are nowadays considered a technology with high development potential. UAVs in the photogrammetric field offer the advantage and possibility of reaching and covering even inaccessible areas of territory with extreme simplicity and in a relatively short time; their contribution has become of fundamental relevance in various fields, including precision agriculture, 3D modeling and security purposes. UAV evolution in recent years has been enhanced by the growing development of miniaturized sensors (optical and LiDAR - Light Detection and Ranging) and by the availability of increasingly efficient navigation systems that integrate inertial systems (IMUs), digital compasses, gyroscopes, GNSS (Global Navigation Satellite System) and GNSS-RTK (GNSS Real Time Kinematic) receivers. In this paper a procedure for security control operations of an area through UAV survey is presented and the possibilities offered by the latest generation of drones in the field of security are analyzed. For this purpose, the presence of objects and people on a building roof are simulated and three surveys have been carried out with different types of drones (with or without GNSS RTK) and sensors (optical or LiDAR). The two models obtained by optical images were processed with photogrammetric algorithms; finally, the two optical and LiDAR point clouds were compared in the open-source software CloudCompare using Cloud to Cloud (C2C) command, which allows to calculate the threedimensional components of the distances between the reference point cloud and the individual points of the other cloud. The results clearly show the identification of people and objects introduced in two of the three surveys performed.