论文标题
使用高分辨率和多回报空气传子数据估计单个树的叶面积密度分布
Estimation of the leaf area density distribution of individual trees using high-resolution and multi-return airborne LiDAR data
论文作者
论文摘要
单个树木的三维结构是了解树木对城市环境的影响所需的重要信息。在这项研究中，我们证明了一种使用高分辨率空气降激龙的叶片面积密度（LAD）分布的方法。此方法改善了先前提出的方法，该方法通过追踪激光束的路径来根据激光束和叶片之间的接触频率来计算LAD。本研究中提出的方法除了第一脉冲和单个脉冲外，还利用了最后的和中间脉冲，以捕获冠的内部内部的叶子分布。每个激光束从由最后一个脉冲得出的点追踪到由最后一个脉冲之前记录的第一个或中间脉冲得出的点。因此，在考虑最后一个和中间脉冲时，可以准确地再现激光束截距和相交。我们使用来自单个树（Z. serrata）的陆生liDar数据来验证三维LAD分布的估计精度。首先通过比较含有一个或多个空气生激光点的体素的分布与包含一个或多个陆地liDAR点的体素的分布来确定用于代表空气传子的LAD分布的适当体素尺寸。随后将体素尺寸为1 m x 0.5 m的体素尺寸为1 m x 0.5 m的估计分布与陆地激光雷达衍生的LAD分布进行比较。当仅使用第一脉冲和单个脉冲时，LAD被高估并在冠的上部和下部被低估了。我们证实，使用最后一个和中间脉冲提高了整个牙冠区域的估计精度。
The three-dimensional structures of individual trees are important pieces of information necessary to understand the effect of trees on urban environments. In this study, we demonstrate a method for estimating the leaf area density (LAD) distribution of individual trees using high-resolution airborne LiDAR. This method improves upon the previously proposed method, which calculates LAD based on the contact frequency between the laser beams and leaves by tracing the paths of the laser beams. The proposed method in this study exploits the last and intermediate pulses in addition to the first and single pulses to capture the foliage distribution in the inner part of the crown. Each laser beam is traced from a point derived by the last pulse to the point derived by the first or intermediate pulse that is recorded immediately before the last pulse. The laser beam interceptions and intersections can thus be accurately reproduced while considering the last and intermediate pulses. We verify the estimation accuracy of the three-dimensional LAD distribution using terrestrial LiDAR data from a single tree (Z. serrata). The appropriate voxel size for representing the LAD distribution from the airborne LiDAR is first determined by comparing the distribution of voxels containing one or more airborne LiDAR points with that containing one or more terrestrial LiDAR points. The estimated LAD distribution with a voxel size of 1 m by 1 m by 0.5 m is subsequently compared to the terrestrial LiDAR-derived LAD distribution. When only the first and single pulses are used, the LAD is overestimated and underestimated in the upper and lower part of the crown, respectively. We confirmed that using the last and intermediate pulses improves the estimation accuracy of the entire crown area.
