Retrieving the gap fraction, element clumping index, and leaf area index of individual trees using single-scan data from a terrestrial laser scanner
Retrieving the gap fraction, element clumping index, and leaf area index of individual trees using single-scan data from a terrestrial laser scanner
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使用地面激光扫描仪的单扫描数据检索单棵树的间隙分数、元素聚集指数和叶面积指数
DOI：
10.1016/j.isprsjprs.2017.06.006
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发表时间：
2017
影响因子：
12.7
通讯作者：
Xu Guangcai
中科院分区：
文献类型：
--
作者：
Li Yumei;Guo Qinghua;Su Yanjun;Tao Shengli;Zhao Kaiguang;Xu Guangcai
地面激光扫描（TLS）是一种很有前途的估算叶面积指数（LAI）的工具。然而，很少有研究在计算“真实”叶面积指数时考虑聚集指数Ω的影响。在这项研究中，我们开发了一种新的点云切片方法的基础上，不同的入射天顶角θ和检索的差距分数使用多个返回信息，以获得更准确的“真正的”LAI估计。此外，本文还提出了一种基于差距大小分析理论的Ω检索方法，以校正树叶遮挡的影响。地面验证数据收集破坏性采样35棵树，并测量所有的叶子。结果表明，基于单次TLS扫描的“真实”LAI估计值与相消采样的LAI测量值之间存在强相关性（R2= 0.76，RMSE = 0.47）。此外，我们的Ω检索方法可以有效地纠正树叶遮挡的影响。其他因素，如切片分辨率，多次返回的激光束的百分比，和扫描距离，对最终的LAI估计的影响很小。
Terrestrial laser scanning (TLS) is a promising tool for estimating leaf area index (LAI). However, very few studies have considered the effect of clumping index Ω in the calculation of “true” LAI. In this study, we developed a new point cloud slicing method based on different incident zenith anglesθand retrieved the gap fraction using multiple-return information to obtain more accurate “true” LAI estimations. In addition, we described a new Ω retrieval method based on the gap size analysis theory to correct the effect of foliage occlusion. Ground validation data were collected by destructively sampling 35 trees and measuring all their leaves. Results show that the TLS-based “true” LAI estimations based on a single TLS scan are strongly correlated with the destructively sampled LAI measurements (R2= 0.76,RMSE= 0.47). Moreover, our Ω retrieval method can effectively correct the effect of foliage occlusion. Other factors, such as the slicing resolution, percentage of laser beams with multiple returns, and scanning distance, have little effect on the final LAI estimation.