Calibration of airborne and spaceborne laser altimeters using natural surfaces

Laser altimetry is an evolving technology in mapping and many other geoscience fields. As the potential of this technology is realized, issues of accuracy, registration and calibration of the data receive growing attention; this can be noticed from the number of publications discussing these issues. The measuring of range instead of reflectivity and the geometric realization of the data acquisition system carry the registration of laser data away from the traditional self-calibration models and theories that were derived in photogrammetry through the years. In fact, they give rise to many questions, for example, how should the calibration of the system be approached, what parameters can be recovered, how reliable can their recovery be, and what affects their reliability. Besides, finding the correspondence between a non-calibrated laser point and the surface element it was reflected from may be at times very difficult. This research aims towards deriving an integrative data registration approach for laser altimetry data. The proposed approach utilizes natural surfaces or manmade objects as the control for registration of laser data. However, the essence of this research lies in using the derived model to answer the questions that were raised above, including a solution for the correspondence problem. The algorithm is derived to handle both airborne and spaceborne systems. With airborne systems