基于机载LiDAR数据的林木冠层投影面积与体积测量  

Measurement of Trees Crown Projection Area and Volume Based on Airborne Li DAR Data

作　　者：张卫正[1] 董寿银 王国飞 裘正军[1] 吴翔[1] 何勇[1] 

机构地区：[1]浙江大学生物系统工程与食品科学学院,杭州310058 [2]浙江省第二测绘院航测与遥感三分院,杭州310012 [3]星际空间(天津)科技发展有限公司,天津300384

出　　处：《农业机械学报》2016年第1期304-309,共6页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家高技术研究发展计划(863计划)项目(2012AA101903)

摘　　要：机载激光雷达系统能够采集反映林木三维结构的点云,利用点云分类及林木冠层投影面积和体积计算方法获得林木信息。通过不规则三角网法和平面拟合过滤算法分别提取地面和建筑物点云,并将建筑物点云过滤得到林木点云,将树冠点云投影到x-y平面,采用角度法搜索边界,提取林木点云边缘,并在与其相对应的CCD影像上显示。利用任意多边形面积算法计算各个连通区域的面积,将它们求和得到冠层投影面积,通过台体的体积计算得到冠层体积。在研究区域随机选出10个外业样地进行传统的人工测量,实验结果表明,基于Li DAR的激光测量与人工测量测得的投影面积和体积的相关系数分别为0.957和0.944。本文提出的方法准确有效,为高精度定量估算林木冠层生物量提供了依据。Airborne Li DAR can obtain three-dimensional structural information of trees and get forest information by using points cloud classification and calculation method of crown projection area and volume. From the distribution of points cloud,the laser pulse formed an once echo when encountered the bare ground and roof of the building,and the distribution of the generated points cloud were smooth and continuous. The laser pulse penetrated vegetation would appear multiple echoes,the distribution rules of the points would be destroyed,and the distribution was in an irregular shape such as cluster-like. First,the points cloud of ground were extracted by using triangulated irregular network,then the points cloud of building were extracted by using planar-fitting filtering algorithm. The points cloud of building were filtered to get points cloud of forest,and then the points cloud of forest were projected onto x-y plane.The edges of points cloud of timber were extracted by using the angle method; its corresponding image was displayed; the area of polygon was calculated by using area algorithm; then the calculation of the projection area of crown was achieved. In the study area,10 experimental districts were randomly selected to carry out the traditional manual measurement. The experimental results showed that the projection area and volume＇s correlation coefficient of the two measurement methods were 0. 957 and0. 944,respectively. The proposed method was feasible to achieve the accurate extraction of forest information rapidly and efficiently which includes a wide range of tree crown projection area and crown volume.

关 键 词：林木 机载Li DAR 投影面积 体积 不规则三角网 平面拟合过滤算法 

分 类 号：TN959.4[电子电信—信号与信息处理] S758.4[电子电信—信息与通信工程]