Automatic in-flight boresight calibration considering topography for hyperspectral pushbroom sensors

This paper suggests a method for automatic in-flight boresight calibration of pushbroom scanner images, using an on-line system with broadband data downlink and near realtime georeferencing of the pushbroom image data. Georeferencing accuracy may decrease during long image acquisition flights due to instable atmospheric conditions, which may lead to geometric changes in the flight platform. Orthorectification of (hyperspectral) pushbroom scanner data demands the knowledge of the extrinsic orientation parameters for every exposure. The most crucial parameters for the transformation of the pose obtained by the inertial navigation system (INS) into the projection center of the imaging sensor are the boresight angles. Utilizing a performant ray tracing algorithm and a digital elevation model (DEM), these parameters can be estimated even while flying in uneven and uninhabited areas. Tie points for solving an extended collinear equation are extracted automatically by the SURF algorithm.