The Autonomous Mini Helicopter: a Powerful Platform for Mobile Mapping

In this paper, the developments related to an autonomous airborne mobile mapping system for photogrammetric processing will be presented. During the last years the author has been involved in several projects related to mobile mapping using an autonomously flying model helicopter, a so-called mini UAV (Unmanned Aerial Vehicle). The overall motivation of using mini UAVs for mobile mapping, the developed workflow for UAV-data processing, the current status of the work, and recent developments related to specific applications are described. In a first step our mini UAV-system and our approach are explained and the need for specific developments is highlighted. In the following two applications will be described: The Randa rockslide and the maize project, demonstrating our developments for the automation of the photogrammetric workflow using the mini UAV system. In the Randa project a unique flight planning tool for UAV-monitoring of mountainous areas was developed. The tool allows for the adaptation of the flight in a way, that image data with 2-3 cm resolution of the cliff could be acquired. Moreover, due to this high image resolution, a DSM with a higher point density compared to standard airborne and helicopter-based LIDAR-systems, could be generated. In the second project the focus was on the automation of the image orientation process. Hence, two test areas (A and B) were defined. While in A two commercial photogrammetric workstation were evaluated, in B the data set was processed using GPS/INS data as initial values for the image orientation. Therefore, the manual input for the aerial triangulation was reduced to a minimum user interaction. Finally, with the oriented image data two DSMs for the analysis of the outcrossing in maize were generated. Because of these developments, the tools for the planning and the data acquisition as well as the workflow for the processing of UAV-images were automated. However, the complete workflow still requires manual interaction, which will be discussed here in detail including a proposal for future developments.