Estimation of vertical plant area density profiles in a rice canopy at different growth stages by high-resolution portable scanning lidar with a lightweight mirror

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• 作者：Fumiki Hosoi ; Kenji Omasa ; ^{aomasa@mail.ecc.u-tokyo.ac.jp}
• 关键词：Laser beam coverage index ; Plant area density ; Portable scanning lidar ; Rice ; Three-dimensional imaging ; Voxel-based canopy profiling
• 刊名：ISPRS Journal of Photogrammetry and Remote Sensing
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：74
• 期：Complete
• 页码：11-19
• 全文大小：944 K

文摘

We used a high-resolution portable scanning lidar together with a lightweight mirror and a voxel-based canopy profiling method to estimate the vertical plant area density (PAD) profile of a rice (Oryza sativa L. cv. Koshihikari) canopy at different growth stages. To improve the laser¡¯s penetration of the dense canopy, we used a mirror to change the direction of the laser beam from horizontal to vertical (0¡ã) and off-vertical (30¡ã). The estimates of PAD and plant area index (PAI) were more accurate at 30¡ã than at 0¡ã. The root-mean-square errors of PAD at each growth stage ranged from 1.04 to 3.33 m² m^?3 at 0¡ã and from 0.42 to 2.36 m² m^?3 at 30¡ã, and those across all growth stages averaged 1.79 m² m^?3 at 0¡ã and 1.52 m² m^?3 at 30¡ã. The absolute percent errors of PAI at each growth stage ranged from 1.8 % to 66.1 % at 0¡ã and from 4.3 % to 23.2 % at 30¡ã, and those across all growth stages averaged 30.4 % at 0¡ã and 14.8 % at 30¡ã. The degree of laser beam coverage of the canopy (expressed as index ¦¸) explained these errors. From the estimates of PAD at 30¡ã, regressions between the areas of stems, leaves, and ears per unit ground area and actual dry weights gave standard errors of 7.9 g m^?2 for ears and 12.2 g m^?2 for stems and leaves.