Integrated UAV-Based Real-Time Mapping for Security Applications

• Main Authors: Daniel Hein, Thomas Kraft, Jörg Brauchle, Ralf Berger
• Format: Article
• Language: English
• Published: MDPI AG 2019-05-01
• Series: ISPRS International Journal of Geo-Information
• Subjects: UAV camera system; rapid mapping; aerial imaging; real-time situation picture; disaster management; image mosaicing; direct georeferencing
• Online Access: https://www.mdpi.com/2220-9964/8/5/219

Security applications such as management of natural disasters and man-made incidents crucially depend on the rapid availability of a situation picture of the affected area. UAV-based remote sensing systems may constitute an essential tool for capturing aerial imagery in such scenarios. While several commercial UAV solutions already provide acquisition of high quality photos or real-time video transmission via radio link, generating instant high-resolution aerial maps is still an open challenge. For this purpose, the article presents a real-time processing tool chain, enabling generation of interactive aerial maps during flight. Key element of this tool chain is the combination of the <i>Terrain Aware Image Clipping</i> (TAC) algorithm and 12-bit JPEG compression. As a result, the data size of a common scenery can be reduced to approximately 0.4% of the original size, while preserving full geometric and radiometric resolution. Particular attention was paid to minimize computational costs to reduce hardware requirements. The full workflow was demonstrated using the DLR <i>Modular Airborne Camera System</i> (MACS) operated on a conventional aircraft. In combination with a commercial radio link, the latency between image acquisition and visualization in the ground station was about 2 s. In addition, the integration of a miniaturized version of the camera system into a small fixed-wing UAV is presented. It is shown that the described workflow is efficient enough to instantly generate image maps even on small UAV hardware. Using a radio link, these maps can be broadcasted to on-site operation centers and are immediately available to the end-users.