GPS/INS Processing

BLOM Aerofilms utilise state of the art integrated GPS / IMU (Inertial Measurement Unit) airborne instruments with our airborne sensors.  The GPS data generally provides the position of the sensor and the IMU data allows the rotations of the sensor to be measured.  For camera systems this allows direct production of the exterior orientation parameters of the imagery.  For LiDAR systems this provides the angle of the scan head which is required to allow construction of the point cloud. 

The GPS and IMU data is logged as part of the raw data capture on board the aircraft.  It is then transferred to our fully digital airborne processing centre together with the flight logs.  The first step is to process the aircraft trajectory using the airborne GPS against 'static' GPS data logged by a ground station during the flight.  This results in a computed position of the aircraft for each second of the survey flight. The time-stamped IMU data is then merged with this GPS trajectory using a series of sophisticated Kalman filter routines which can be specifically tuned according to the dynamics of the flight. The final result is a highly accurate, time stamped trajectory which includes the smoothed position and the attitude of the aircraft at each point on the survey flight