Autonomous geo-referenced aerial reconnaissance for instantaneous applications

The Fraunhofer Institute of Optronics, System Technologies and Image Exploitation (IOSB) deals with the interoperability of stationary and mobile sensors and the development of assistance systems, which optimize and simplify the operation of such systems. One focus is research on swarms with airborne miniature drones and their applications. The photo flight presented in this paper is one of the applications developed to bring the advantages of a swarm into a realistic scenario. With the aim to support rescue or security forces in action, the photo flight generates an immediate up-to-date situation picture by using an autonomous swarm of miniature drones. If the videos taken from these swarms are georeferenced, a significantly better coordination and distribution of missions and tasks can be achieved. Therefore, the ability of geo-referencing in unknown terrain is highly demanded. In the absence of an onboard internal navigation system, an imagebased approach is proposed. It consists of registration of video frames or even whole sequences stemming from different UAVs into a common coordinate system and matching with an orthophoto. These processes are called quasi-intrasensorial and intersensorial registration. For image-based georeferencing, a differentiation must be made between scenes with negligible spatial depth (2D situation) and those where the depth cannot be neglected any longer (2.5D situation). Several applications of geo-referenced UAV-borne videos as well as ideas how the task of image-based geo-referencing can be accelerated for online processing are presented.