MOBILE STEREO-MAPPER: A PORTABLE KIT FOR UNMANNED AERIAL VEHICLES

A low-cost portable light-weight mobile stereo-mapping system (MSMS) is under development in the GeoICT Lab, Geomatics Engineering program at York University. The MSMS is designed for remote operation on board unmanned aerial vehicles (UAV) for navigation and rapid collection of 3D spatial data. Pose estimation of the camera sensors is based on single frequency RTK-GPS, loosely coupled in a Kalman filter with MEMS-based IMU. The attitude and heading reference system (AHRS) calculates orientation from the gyro data, aided by accelerometer and magnetometer data to compensate for gyro drift. Two low-cost consumer digital cameras are calibrated and time-synchronized with the GPS/IMU to provide direct georeferenced stereo vision, while a video camera is used for navigation. Object coordinates are determined using rigorous photogrammetric solutions supported by direct georefencing algorithms for accurate pose estimation of the camera sensors. Before the MSMS is considered operational its sensor components and the integrated system itself has to undergo a rigorous calibration process to determine systematic errors and biases and to determine the relative geometry of the sensors. In this paper, the methods and results for system calibration, including camera, boresight and leverarm calibrations are presented. An overall accuracy assessment of the calibrated system is given using a 3D test field