圆扫描式机载激光测深系统检校模型及仿真分析

The Calibration Model and Simulation Analysis of Circular Scanning Airborne Laser Bathymetry System

为了提升圆扫描式机载激光测深系统的定位精度,提出了一种检校思路:在平面区域获取激光点云时,系统误差和随机误差使得本应共面的激光点云不再共面,通过将激光点云拟合到单个平面上达到纠正点云位置的目的。首先推导了简单模式下圆扫描式机载激光测深系统定位模型,并从直线与平面交会的数学原理出发模拟激光光线与海面的交会过程,根据折射原理解算激光光线在水中的方向矢量,联合激光光线在水中的直线方程和海底面数学方程解算激光脚点的位置。然后,引入未知数先验方差,推导了参数加权最小二乘平差模型,为后面检校模型的解算奠定基础。最后,推导了用于检校的平差数学模型和详细的计算过程,对检校过程进行了模拟计算和分析讨论,得出了一些有益于检校过程的结论。

To improve the positioning accuracy of circular scanning airborne laser bathymetry system,a calibration method is presented in this paper.When the laser points are collected by the bathymetry system on the level area,they should be on the same plane.However,they are not coplanar because of systematic error and random error.So we try to fit the points to a plane,which may help to adjust the errors and then correct the point location.Firstly,the circular scanning airborne laser bathymetry positioning model is derived in the simple mode.The intersection of laser line and sea surface is simulated depending on the mathematical principles of line and plane intersection.Combined with the direction vector of laser line in the water got by the refraction principle,the sea floor plane mathematical equation is used to compute the location of the laser points.Then,the parameter weighted least squares adjustment model is derived with the prior variance introduced,which lays the foundation for the following computing of calibration model. Finally,the calibration adjustment mathematic model and the detailed computing process are derived.The simulation computing and analysis for the calibration process is presented,and some meaningful conclusions for the calibration are achieved.