摘要
为提高背包式激光雷达(Backpack laser scanning,缩写为BLS)数据提取林木胸径精度,本文通过滤除BLS扫描数据与周围最近的点距离超过10 cm的噪音点,使用不规则三角网算法提取出地面点,并把点云高程值减去对应的地面点高程值将点云数据进行高程归一化处理,在高程为0.8~1.8 m,以0.1 m为步长进行切片,通过滤除不同点云强度的点云来提取胸径,将每株树木中所有切片拟合圆的直径选取最小值作为这株树木的胸径,将试验结果、实测数据及只经过预处理的点云提取胸径的结果进行比对。结果显示,通过滤除低强度点云分别使3块样地的均方根误差(Root mean square error,RMSE)分别从2.63 cm降低到0.99 cm、从5.43 cm降低到4.72 cm、从4.01 m降低到2.15 cm;平均误差分别从1.90 cm降低到0.79 cm,从5.24 cm降低到4.16 cm,从3.36 cm降低到1.58 cm。BLS扫描的林木数据中,在胸径位置处的点云强度低的点云属于拼接误差较大的点云,会影响胸径提取结果的精度,滤除掉这部分点云可以提升精度,拼接误差较大的点云所占比例与地形有关,坡地低质量点云所占比例大于平地。
In order to improve the accuracy of extracting tree breast diameter from backpack laser scanning(BLS)data,this paper filtered out the noise points whose BLS scan data was more than 10 cm away from the nearest point,and used the irregular triangulation algorithm to extract the ground point,and subtracted the elevation value of the point cloud from the corresponding ground point elevation value to normalize the elevation of the point cloud data.At an elevation of 0.8 to 1.8 m,slice with a step of 0.1 m,and filter out different point clouds to extract DBH.The smallest diameter of the fitting circle of all slices in each tree was selected as the diameter at breast height of the tree,and the results of the test results,measured data and the results of extracting DBH from point cloud only after preprocessed were compared.The results showed that by filtering out low intensity point clouds,the root mean square error(RMSE)of the three plots were reduced from 2.63 cm to 0.99 cm,5.43 cm to 4.72 cm,and 4.01 m to 2.15 cm,the average error decreased from 1.90 cm to 0.79 cm,5.24 cm to 4.16 cm,and 3.36 cm to 1.58 cm.In the forest data scanned by BLS,the point cloud with low intensity at breast diameter was a point cloud with large stitching error,which would affect the accuracy of the breast diameter extraction result.Filtering out this part of the point cloud can improve the accuracy.The proportion of large stitching error point clouds was related to the terrain,and the proportion of low quality point clouds on slopes was larger than that on flat ground.
作者
蔡硕
邢艳秋
端木嘉龙
CAI Shuo;XING Yanqiu;DUANMU Jialong(College of Engineering and Technology,Northeast Forestry University,Harbin 150040,China)
出处
《森林工程》
北大核心
2021年第5期12-19,共8页
Forest Engineering
基金
国家重点研发计划项目(2017YFD060090402)
中央高校基本科研业务费专项资金项目(2572019AB18)。
作者简介
第一作者:蔡硕,硕士研究生。研究方向为森工管理及林业信息工程。E-mail:1070199475@qq.com;通信作者:邢艳秋,博士,教授,博士生导师。研究方向为森工管理及林业信息工程。E-mail:yanqiuxing@nefu.edu.cn。
