Geometric calibration of satellite laser altimeters based on waveform matching

This study proposes a new geometric calibration method for satellite laser altimeters based on waveform matching to solve the problems of poor initial pointing accuracy and a lack of control data. This non-real-time method obtains ground control points without a fixed calibration field. First, a large area with stepped surfaces is chosen from the laser altimetry coverage. Then, the laser echo waveforms are simulated using digital surface model (DSM) data of the stepped features. The real echo waveform attempts to match the simulated echo waveforms through a waveform matching model using a global constraint. Next, the control points of the laser altimeter are obtained through waveform matching. Finally, a geometric calibration model for laser altimeters is proposed to compensate for laser pointing and ranging errors. Two experiments were conducted to verify the calibration method using ICESat/GLAS data and airborne large-footprint laser data. Experimental results confirm that the method is feasible and results in an improvement in the elevation accuracy for the airborne altimeter from 2 to 0.5 m.