Legat, Skaloud, Schaer TOPO-EPFL Real-time processing of GPS/INS data for on-the-fly quality control in airborne mobile mapping Klaus Legat 1, 2 , Jan Skaloud 1 , Philipp Schaer 1 1 Laboratoire de Topométrie (TOPO), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH 2 Institute of Navigation and Satellite Geodesy (INAS), Graz University of Technology, AUT Biographies Klaus Legat (legat@tugraz.at ), born in 1975, holds a Dipl.-Ing. and Dr.techn. in geodesy from Graz University of Technology where he is engaged at the Institute of Navigation and Sat- ellite Geodesy. In June 2005, he joined the geomatics lab at the EPFL in the scope of an Erwin-Schrödinger Fellowship granted by the Austrian Science Fund (FWF). Jan Skaloud (jan.skaloud@epfl.ch ), born in 1969, is a senior scientist and lecturer at the EPFL. He holds a PhD and MSc in Geomatics Engineering from the University of Calgary and conducts research in GPS/INS/sensor integration, mobile mapping, and kinematic geodesy. Philipp Schaer (philipp.schaer@epfl.ch ), born in 1977, received his MSc in environmental engineering from the EPFL in 2003. Afterwards he joined Swissphoto SA in Zurich, where he mainly worked as a project leader in Lidar survey projects. After two years he returned to the EPFL to start a PhD thesis within the TOPO lab. His thesis deals with the project i-Qual (in- flight quality assessment of airborne Lidar, http://topo.epfl.ch/laserscanning/research.en.php ) that is done in cooperation with Swissphoto and supported by the Swiss Innovation Promotion Agency (CTI). Abstract Scan2Map is an airborne remote-sensing system developed under the lead of the TOPO lab at the EPFL. Typically operated aboard a helicopter, it is dedicated for small mission areas (a few square kilometres at the maximum) and offers a sub-decimetre accuracy of the derived mapping products (orthophotos, digital surface- and terrain models). To achieve this high quality independently from ground control, Scan2Map relies on GPS/INS for determining the parameters of exterior orientation of the image sensors (i.e., a digital camera and a Lidar line scanner). In order to guarantee the complete coverage of a given area of interest, a detailed flight plan needs to be elaborated and it is essential to follow this plan as closely as possible during the flight. However, certain types of problems may remain hidden during the data recording, e.g., insufficient Lidar coverage due to poor ground reflectance. To avoid suchlike situations, an online monitoring tool is currently under development that allows assessing the quality of the recorded data while in the air. Among other calculations, this tool requires the real-time processing of the GPS/INS data. The paper describes the principles of airborne mobile mapping by Scan2Map, discusses cer- tain aspects of the real-time GPS/INS processing, and shows some initial results obtained during the development of the quality-assessment tool. ENC-GNSS 2006, Manchester, May 7-10 1