Precise Multi-Sensor Georeferencing System for Micro UAVs

The direct georeferencing technique in aerial photogrammetry using micro Unmanned Aerial Vehicles (UAV) is not commonly used against indirect approach due to high requirements of equipment and calibration. On the other hand this technique brings several advantages which can be beneficial in some applications. This paper deals with the development and testing of precise multi-sensor system for the direct georeferencing of aerial imagery. The system consist of dual-antenna Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) receiver with centimeter level accuracy and Inertial Navigation System (INS) which fuses inertial and position information to provide accurate navigation and orientation data in real time. Special attention is paid to the time synchronization of various sensor data and lever arm correction. 3D print technology was used to achieve low weight and high modularity of the system which can be easily modified and mounted to different types of UAVs. This paper also describes a test flight mission and the processing workflow from the data acquisition to the import of georeferenced orthophoto to a Geographic Information System (GIS).