Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects
Discrete point cloud data from unmanned aerial vehicle laser scanning (UAV-LS) can provide information on the three-dimensional structure of a forest, the leaf area index (LAI) at the landscape or sample plot scales, the distribution of the vertical forest structure at a fine resolution, and other i...
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| Format: | Article |
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MDPI AG
2022-08-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/13/8/1221 |
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| author | Yang Liu Yu Shan Hong Ying Du Wala Xiang Zhang A Ruhan Su Rina Su Rina |
| author_facet | Yang Liu Yu Shan Hong Ying Du Wala Xiang Zhang A Ruhan Su Rina Su Rina |
| author_sort | Yang Liu |
| collection | DOAJ |
| description | Discrete point cloud data from unmanned aerial vehicle laser scanning (UAV-LS) can provide information on the three-dimensional structure of a forest, the leaf area index (LAI) at the landscape or sample plot scales, the distribution of the vertical forest structure at a fine resolution, and other information. The retrieved parameters, however, may be affected in a non-negligible way by the inclusion of scan angle information. In this study, we introduced a relational model that encompasses the angular effect, predicted the mechanism of this effect, and extracted the vegetation structure indices that the angular effect might influence. Second, we quantified the direct and indirect effects, particularly the magnitude of the angular effect in broadleaf forests, and used mediated effects to investigate the components and processes that influence the angular effect. The findings demonstrate that some of the differences between the LAIe extracted by UAV-LS and the Decagon LAIe considering the angular effect of UAV-LS can be explained by adjusting physical LiDAR parameters (aerial height, laser divergence fraction, and scanning angle) and vertical forest structure variables. Along continuous and closed forest vertical gradients, the indirect angle impact is negative for the upper canopy and positive for the understory. Three-dimensional vegetation measurements were created using multiangle LiDAR data. In conclusion, this article (1) addresses the angular effect in UAV-LS; and (2) discusses how the angular effect affects 3D vegetation parameters such as LAIe, demonstrates the nonlinear trend of the angular effect, and demonstrates how multiangle LiDAR data can be used to obtain 3D vegetation parameters. This study serves as a reference for reducing the uncertainty in simulations of the angular effect and vegetation light transmission, in addition to the uncertainty in analyses of the vegetation characteristics determined by UAV-LS (e.g., the uncertainty of LAIe). |
| first_indexed | 2024-03-09T13:25:25Z |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-09T13:25:25Z |
| publishDate | 2022-08-01 |
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| series | Forests |
| spelling | doaj.art-7df97732eb2a4da3b353a8557e901cbe2023-11-30T21:24:41ZengMDPI AGForests1999-49072022-08-01138122110.3390/f13081221Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating EffectsYang Liu0Yu Shan1Hong Ying2Du Wala3Xiang Zhang4A Ruhan5Su Rina6Su Rina7College of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaChinese Academy of Agricultural Sciences Grassland Research Institute, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaCollege of Geographic Science, Inner Mongolia Normal University, Hohhot 010022, ChinaDiscrete point cloud data from unmanned aerial vehicle laser scanning (UAV-LS) can provide information on the three-dimensional structure of a forest, the leaf area index (LAI) at the landscape or sample plot scales, the distribution of the vertical forest structure at a fine resolution, and other information. The retrieved parameters, however, may be affected in a non-negligible way by the inclusion of scan angle information. In this study, we introduced a relational model that encompasses the angular effect, predicted the mechanism of this effect, and extracted the vegetation structure indices that the angular effect might influence. Second, we quantified the direct and indirect effects, particularly the magnitude of the angular effect in broadleaf forests, and used mediated effects to investigate the components and processes that influence the angular effect. The findings demonstrate that some of the differences between the LAIe extracted by UAV-LS and the Decagon LAIe considering the angular effect of UAV-LS can be explained by adjusting physical LiDAR parameters (aerial height, laser divergence fraction, and scanning angle) and vertical forest structure variables. Along continuous and closed forest vertical gradients, the indirect angle impact is negative for the upper canopy and positive for the understory. Three-dimensional vegetation measurements were created using multiangle LiDAR data. In conclusion, this article (1) addresses the angular effect in UAV-LS; and (2) discusses how the angular effect affects 3D vegetation parameters such as LAIe, demonstrates the nonlinear trend of the angular effect, and demonstrates how multiangle LiDAR data can be used to obtain 3D vegetation parameters. This study serves as a reference for reducing the uncertainty in simulations of the angular effect and vegetation light transmission, in addition to the uncertainty in analyses of the vegetation characteristics determined by UAV-LS (e.g., the uncertainty of LAIe).https://www.mdpi.com/1999-4907/13/8/1221UAV-LSdiscrete point cloudangular effectsforest vertical vegetation metriceffective leaf area index |
| spellingShingle | Yang Liu Yu Shan Hong Ying Du Wala Xiang Zhang A Ruhan Su Rina Su Rina Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects Forests UAV-LS discrete point cloud angular effects forest vertical vegetation metric effective leaf area index |
| title | Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects |
| title_full | Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects |
| title_fullStr | Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects |
| title_full_unstemmed | Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects |
| title_short | Examining the Angular Effects of UAV-LS on Vegetation Metrics Using a Framework for Mediating Effects |
| title_sort | examining the angular effects of uav ls on vegetation metrics using a framework for mediating effects |
| topic | UAV-LS discrete point cloud angular effects forest vertical vegetation metric effective leaf area index |
| url | https://www.mdpi.com/1999-4907/13/8/1221 |
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