无人机航拍参数对林木冠层三维点云重构的影响  

Impact of drone aerial photography parameters on 3D point cloud reconstruction of tree canopy

作　　者：魏倪彬 余坤勇[2,3] 刘健[2,3] WEI Nibin;YU Kunyong;LIU Jian(College of JunCao Science and Ecology,Fujian Agriculture and Forestry University,Fuzhou,Fujian 350002,China;University Key Lab for Geomatics Technology and Optimize Resource Utilization in Fujian Province,Fujian Agriculture and Forestry University,Fuzhou,Fujian 350002,China;College of Forestry,Fujian Agriculture and Forestry University,Fuzhou,Fujian 350002,China)

机构地区：[1]福建农林大学菌草与生态学院,福建福州350002 [2]福建农林大学3S技术与资源优化利用福建省高校重点实验室,福建福州350002 [3]福建农林大学林学院,福建福州350002

出　　处：《福建农林大学学报(自然科学版)》2025年第3期410-419,共10页Journal of Fujian Agriculture and Forestry University:Natural Science Edition

基　　金：“十四五”国家重点研发计划课题(2023YFD2201205);国家自然科学基金面上项目(32271876)。

摘　　要：【目的】探究3种航拍参数(飞行高度、航向重叠度、旁向重叠度)对林木冠层三维点云重构及其结构参数估算精度的影响,为提升无人机影像点云(drone-based image point clouds,DIPC)在冠层结构监测中的应用能力提供参考。【方法】以桂花树林为研究对象,设置4组飞行高度(40、80、120、160 m)、3组航向重叠度(70%、80%和90%)和3组旁向重叠度(70%、80%和90%)采集DIPC数据。利用地基激光雷达数据,对不同飞行参数下DIPC的重构质量(通过点云高程变异系数衡量)以及冠层结构参数(树冠体积、树冠垂直投影面积、冠幅、冠长和树高)的估算精度进行评价。【结果】在80~160 m飞行高度,DIPC的高程变异系数显著降低;在40~120 m,冠层结构参数的估算精度较高且趋于稳定,但在120~160 m,其估算精度显著降低。随着航向重叠度的升高,DIPC的高程变异系数逐渐升高;航向重叠度为70%~80%时,冠层结构参数的估算精度显著升高,但航向重叠度为80%~90%时,其估算精度的变化趋于稳定。随着旁向重叠度的升高,DIPC的高程变异系数呈升高趋势;旁向重叠度为70%~80%时,冠层结构参数的估算精度显著升高,旁向重叠度为80%~90%时,其估算精度的变化趋于稳定。【结论】航向与旁向重叠度由70%增至80%对冠层结构参数估算精度提升作用最大,且航向重叠度对冠层结构参数估算精度的影响大于旁向重叠度。飞行高度由120 m增至160 m会显著降低冠层结构参数的估算精度。【Objective】This study explored the impact of 3 aerial photography parameters(flight height,forward overlap and side overlap)on the three-dimensional(3D)point cloud reconstruction of forest canopy and the precision of structural parameter estimation,aiming to provide a reference for enhancing the application capability of drone-based image point cloud(DIPC)in canopy structure monitoring.【Method】With Osmanthus forest as the research subject,its DIPC data were collected at different flight heights(40,80,120 and 160 m),forward overlaps(70%,80%and 90%)and side overlaps(70%,80%and 90%).Ground-based LiDAR data was used to evaluate the reconstruction precision(according to the elevation variation coefficient of point cloud)and estimation precision of canopy structural parameters(canopy volume,vertical projection area of canopy,canopy width,canopy length and tree height)based on DIPC under different flight parameters.【Result】The variation coefficient of DIPC-based elevation declined dramatically with flight height between 80 and 160 m,and the estimation precision of canopy structural parameters based on DIPC was high and trended to stabilize at flight height of 40-120 m,but decreased rapidly at 120-160 m.The variation coefficient of DIPC-based elevation trended to increase with forward overlap or side overlap.The estimation precision of canopy structural parameters based on DIPC increased significantly with forward overlap(70%-80%)or side overlap(70%-80%),and was stabilized when forward overlap or side overlap arrived at 80%-90%.【Conclusion】The increase of forward overlap and side overlap from 70%to 80%exerted the most significant effects on lifting the estimation precision of canopy structure parameter,with greater impacts from forward overlap;however,raising flight height from 120 m to 160 m significantly lowered the estimation precision of canopy structure parameters.

关 键 词：林木冠层 三维结构 无人机遥感 点云数据 飞行高度 图像重叠度 

分 类 号：S771.8[农业科学—森林工程] TP79[农业科学—林学]