ESTIMATION OF OPTO-MECHANICAL PARAMETERS FOR CALIBRATION OF LASER SCANNERS

摘要

Within this paper an approach of calibration for a terrestrial laser scanner with two mirrors driven by two galvanometers is presented. This includes a mathematical model for the interior of the laser scanner as well as the determination for the parameters to be calibrated. The mathematical model is derived from the functionality of the laser scanner, whereby the principle of "Ray Tracing" was used. According to the inner structure of the scanner device and the functionality of the scanning system the laser ray would be divided into three parts. Every part could be represented by a metric length and a unit vector which could be deduced by using the algorithm in triangular angers and the matrix of reflection respectively. The mathematical model is then the result of combination of these three vectors of laser parts. It was suspected that the lengths of the laser ray and the angles of the mirror rotations were obtained inexactly during measurement. However they could be corrected by adding offsets and factors for the scale caused by not exact orthogonal configuration of the mirror axes. In order to estimate these parameters the adjustment model was established using the Gauss-Markov-Model. Results from the test with simulated data showed that the mathematical model and the adjustment model were adequate to the presented approach.