Geometrical and physical models of a 3D range finder

According to the problem to be dealt with, the use of data acquisition system requires the knowledge of several models. In the case of the laser range-finder mounted on a site and azimuth turret, the geometrical model defines the co-ordinate transformation between measurement and reference frames. The paper shows the interest of a global calibration in comparison with a more classical approach which divides the problem into an internal model and external one. During the acquisition process another model called ´physical model´ may be useful. It takes into account the fact the laser beam impact is not at a point and introduces a spatial integration. The so-called footprint effect limits the lateral resolution of the range finder at depth discontinuities. In order to correct that effect, an inverse physical model, based on neural networks, is proposed. The improvement of the footprint correction is then evaluated for a 2D and 3D scanning.