GROUND SURFACE ESTIMATION FROM AIRBORNE LASER SCANNER DATA USING ACTIVE SHAPE MODELS

Various filtering techniques exist to obtain the ground from laser radar data to use when building digital terrain models. This paper develops an active shape model approach to estimate the ground surface from laser radar data. The active shape model acts like a rubber cloth with elasticity and rigidity. With constraint forces the model is formed to an estimate of the ground surface. The model is glued against the measured points from underneath, forming the envelope of the point cloud. Even in a thick forest as much as 25 per cent of the data points represent the ground. The stiffness of the shape model stretches it out to a continuous surface in between the ground points. The algorithm implemented in this paper is suited to use on very dense data sets, it has been designed for data sets of more than 10 points per square meter. We propose suggestions of changes to the algorithm to adjust it to work on more sparse data sets.