机载LIDAR激光束与扫描镜对准误差影响分析

Error analysis on laser beam misalignment with scanner mirror of airborne LIDAR

激光束与扫描镜对准误差是影响机载LIDAR定位精度的因素之一。以摆动扫描方式机载LIDAR系统为例,将激光束与扫描镜对准误差分解为水平和垂直对准误差,从机载LIDAR定位原理出发,定性和定量分析了两误差分量对LIDAR定位精度的影响。研究分析表明,激光束与扫描镜对准误差对摆动扫描LIDAR定位精度的影响随高度和扫描角的增加而增大,其中水平对准误差对X坐标产生的影响导致扫描线在航线方向产生抛物线型变形偏移;垂直对准误差对Y坐标的影响导致扫描线整体向左或者向右偏移,对Z坐标产生的影响与偏心角中侧滚角误差对高程产生的影响相似,两者影响在常规标定方法中难于区分,应在仪器出厂时通过严格检校消除或削弱激光束与扫描镜的对准误差。

Laser beam misalignment with scanner mirror is one of the error sources influencing the accuracy of airborne LIDAR.Laser beam misalignment with scanner mirror was decomposed into the vertical and horizontal components, and its effect on scanning line distortion and positioning accuracy were analyzed quantitatively and qualitatively based on the principles of airborne LIDAR. The analysis demonstrates that the horizontal misalignment causes the X coordinates of the scanning line a parabola-like distortion in the flight direction; the vertical misalignment makes the Y coordinates of the scanning line a left or right shift and causes a parabola-like distortion on the Z coordinates of the scanning line which is similar to the influence of the roll mounting errors, and therefore can＇t be eliminated by common adjustment methods but by calibration by manufacturer. Besides, laser beam misalignment influences the scanning line distortion and positioning accuracy more when the height and scanning angle were increased.