多级移动曲面拟合的自适应阈值点云滤波方法

为了提高机载激光雷达点云滤波算法的精度、效率以及自适应性，提出了一种多级移动曲面拟合的自适应阈值点云滤波方法。首先，对点云数据进行预处理即剔除粗差，然后通过格网化分割建立格网索引，利用每个格网的邻域格网中的最低点建立曲面方程，计算真实高程与拟合高程的差值并设置自适应性阈值进行滤波，最后采用多级滤波策略，即逐级改变格网大小并自动设置邻域和阈值，直到滤波结果达到精度要求。使用国际摄影测量与遥感学会（ISPRS）提供的测试数据对算法进行验证，第1、2类误差和总误差平均值分别为7.33%、10.64%、6.34%。将该算法与ISPRS公布的8大经典滤波算法进行比较，结果表明该方法的适应性强，滤波结果具有较高的准确性。

Hierarchical Threshold Adaptive for Point Cloud Filter Algorithm of Moving Surface Fitting

In order to improve the accuracy,efficiency and adaptability of point cloud filtering algorithm,a hierarchical threshold adaptive for point cloud filter algorithm of moving surface fitting was proposed.Firstly,the noisy points are removed by using a statistic histogram method.Secondly,the grid index is established by grid segmentation,and the surface equation is set up through the lowest point among the neighborhood grids.The real height and fit are calculated.The difference between the elevation and the threshold can be determined.Finally,in order to improve the filtering accuracy,hierarchical filtering is used to change the grid size and automatically set the neighborhood size and threshold until the filtering result reaches the accuracy requirement.The test data provided by the International Photogrammetry and Remote Sensing Society (ISPRS) is used to verify the algorithm.The first and second error and the total error are 7.33％,10.64％ and 6.34％ respectively.The algorithm is compared with the eight classical filtering algorithms published by ISPRS.The experiment results show that the method has well-adapted and it has high accurate filtering result.