Retrieving forest canopy extinction coefficient from terrestrial and airborne lidar
Retrieving forest canopy extinction coefficient from terrestrial and airborne lidar
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DOI：
10.1016/j.agrformet.2017.01.004
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发表时间：
2017-04
影响因子：
6.2
通讯作者：
Lixia Ma;G. Zheng;J. Eitel;T. Magney;L. M. Moskal
中科院分区：
文献类型：
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作者：
Lixia Ma;G. Zheng;J. Eitel;T. Magney;L. M. Moskal
准确反演植被要素的消光系数是进行森林冠层内和冠层下辐射状况空间制图的关键步骤。在利用激光雷达数据提取三维体素进行遥感反演的过程中，叶素的方位角（由叶素的法向量表征）是影响反演精度的重要因素。在这项工作中，我们首先开发和验证了一种方法来retrievekfor森林冠层，同时考虑倾斜角和方位角从地面激光扫描（TLS）数据。然后，我们探讨了应用所提出的方法的可行性航空激光扫描（ALS）数据通过四个点的稀疏实验阔叶树和针叶树。我们的研究结果表明：（1）基于TLS的叶向定位可以捕获86%的（N = 209，p < 0.001）和64%（N = 78，p < 0.001）的方差，（2）所提出的基于激光雷达的K反演方法可以应用于基于ALS和TLS的森林激光雷达数据;（3）叶素方位角是影响森林冠层k的重要因素，TLS和ALS平台对森林k的影响不同。使用这个新的框架，我们能够使用激光雷达数据来模拟森林冠层内光合有效辐射的预期时空分布。
Accurately retrieving the extinction coefficient (k) of foliage elements is a key step to spatially mapping the radiation regime within and under a forest canopy. The azimuthal angle of foliage elements (characterized by their normal vectors) is an important factor for improving the retrieval accuracy ofkusing 3-D voxels derived from lidar data. In this work, we first developed and validated an approach to retrievekfor a forest canopy by considering both inclination and azimuthal angles from terrestrial laser scanning (TLS) data. Then, we explored the feasibility of applying the proposed method to aerial laser scanning (ALS) data through four point thinning experiments for both broadleaf and coniferous trees. Our results showed that: (1) TLS-based foliage orientation could capture 86% (N = 209, p < 0.001) and 64% (N = 78, p < 0.001) of the variance in manually measured azimuthal and inclination angles, respectively for an artificial broadleaf tree; (2) the proposed lidar-basedkretrieval method can be applied to both ALS- and TLS- based forest lidar data; and (3) the azimuthal angle of foliage elements is an important factor for retrievingkof a forest canopy, and both TLS and ALS platforms have differing effects on the estimates of forestk. Using this new framework, we were able to use lidar data to model the expected spatio-temporal distribution of photosynthetically active radiation within forest canopies.