The comparative study of direct-georeferenced Unmanned Airborne Vehicle geospatial information acquisition platform

To facilitate applications such as environment detection, military security, or disaster monitoring, a quickly and low-cost system for collecting near real-time spatial information is very important. Rapid spatial information collection has become a trend in remote sensing and mapping applications. In this study, a fixed-wing Unmanned Airborne Vehicle (UAV) based spatial information collection platform is proposed. The proposed UAV based platform has a direct geo-referencing ready module, including an integrated Positioning and Orientation System (POS) that is composed of the Global Positioning System (GPS) and an Inertial Navigation System (INS), a low cost digital camera, a video monitoring communication system, and other sensors mounted on the platform. To validate the performance of the proposed platform, some field tests were conducted in 2009 and 2010. The preliminarily results indicate that the Ground Sample Distance (GSD) reached 6 centimeters and the three-dimensional (3D) positioning accuracy reached 10 centimeters for a flight height of 300 meters. For flight heights of 600 and 900 meters, the GSDs are 17 and 19 centimeters and the 3D positioning accuracies are 23 and 50 centimeters, respectively. In addition, a Digital Elevation Model (DEM) is generated using a numerical photogrammetry workstation with the images and POS information acquired by the proposed platform. The elevation accuracy of the check points is 0.144 meters and the positioning accuracies for the x and y axes are 0.049 and 0.027 meters, respectively. The proposed platform was sent to collect spatial information for disaster assessment after Typhoon Morakt hit southern Taiwan in summer 2009.