基于计算机图形和多孔介质的树冠孔隙率反演
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引用本文:李冬妮,薛联凤.基于计算机图形和多孔介质的树冠孔隙率反演[J].计算技术与自动化,2023,(1):138-145
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李冬妮,薛联凤 (南京林业大学 信息科学技术学院江苏 南京 210037) 
中文摘要:树冠孔隙率(GF)决定了光和气流穿过树冠与植被元素相互作用进行光合作用和蒸腾的传输情况,在多孔介质理论启发下,受计算机图形学的启发,将树冠中的植被元素定量为固体矩阵,将树冠中的缝隙作为孔隙来指导GF计算。通过从地面激光扫描数据中提取单个叶片,并采用拟合算法去除噪声和描绘叶片边缘,创新地定义了叶片卷曲和下垂程度的等效厚度,并从拟合点中计算出来。然后,用自适应尺寸分配的六边形棱镜包住每片叶子的扫描点,用圆柱体模型拟合每个枝干,以计算树冠的等效叶子和枝干体积。结果显示,分割的叶片数为紫薇(1193片)、樱花(2540片)以及含笑(379片),估计的GF分别为:紫薇0.990,樱花树0.976,含笑0.978。
中文关键词:冠层孔隙率  计算机图形学  多孔介质理论  精细尺度表示  等效叶片厚度
 
Canopy Gap fraction Inversion Based on Porous Media and Computer Graphics
Abstract:Canopy gap fraction (GF) determines the transmission of light and airflow through the canopy and interacting with vegetation elements for photosynthesis and transpiration. Inspired by the theory of porous media and inspired by computer graphics, this work quantifies the vegetation elements in the canopy as a solid matrix, and uses the gaps in the canopy as pores to guide the GF calculation. By extracting individual leaves from terrestrial laser scan data, and applying a fitting algorithm to remove noise and delineate leaf edges, an equivalent thickness describing the degree of leaf curl and sag was innovatively defined and calculated from the fitted points. Then, the scan points of each leaf were wrapped with adaptive size-assigned hexagonal prisms, and each branch was fitted with a cylinder model to calculate the equivalent leaf and branch volumes of the canopy. The results show that the number of divided leaves is crepe myrtle (1183 pieces), sakura (2540 pieces) and Michelia figo (379 pieces), the estimated GF are 0.990 for the crepe myrtle, 0.976 for the sakura tree and 0.978 for the Michelia figo, respectively.
keywords:canopy gap fraction  computer graphics  porous media theory  fine-scale representation  equivalent leaf thickness
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