Institute of Science, Beijing Forestry University, Haidian District, Beijing, China.
PLoS One. 2019 Jan 17;14(1):e0209888. doi: 10.1371/journal.pone.0209888. eCollection 2019.
A terrestrial laser scanner is a fast, high-precision data acquisition device, which has been applied more and more to the research area of forest inventory. In this study, a type of automated low-cost terrestrial laser scanner was designed and implemented based on a SICK LMS-511 two-dimensional laser scanning sensor and a stepper motor. The new scanner was named BEE(developed by the department of Electronic Engineering, Beijing Forestry University), which can scan the forest trees in three dimensions. The BEE scanner and its supporting software are specifically designed for forest inventory. The specific software was developed to smoothly control the BEE scanner and to acquire the data, including the angular data, range data, and intensity data, and the data acquired by the BEE scanner could be processed into point cloud data, a range map, and an intensity map. Based on the point cloud data, the trees were detected by a single slice of the single scan in a plot, and the local ground plane was fitted for each detected tree. Then the diameter at breast height (DBH), tree height, and tree position could be estimated automatically by using the specific software. The experiments have been performed by using the BEE scanner in an artificial ginkgo forest which was located in the Haidian District of Beijing. Four 10 m × 10 m square plots were selected for the experiments. The BEE scanner scanned in the four plots and acquired the single-scan data, respectively. The DBH, tree height, and tree position of the trees in the four plots were estimated and analyzed. For comparison, manually-measured data was also collected in the four plots. The trunk detection rate for all four plots was 92.75%; the root mean square error of the DBH estimation was 1.27 cm; the root mean square error of the tree height estimation was 0.24 m; and the tree position estimation was in line with the actual position. The scanner also was tested in more natural forest in the JiuFeng Forest Park. Two plots with a radius of 5 meters were scanned. Eleven trees in the plot with a flat ground were detected and DBH were estimated. But tree detection was failed in the other plot because of the undulating ground. Experimental results show that the BEE scanner can efficiently estimate the structure parameters of plantation trees and has good potential in practical applications of forest inventory.
地面激光扫描仪是一种快速、高精度的数据采集设备，已越来越多地应用于森林清查研究领域。本研究基于 SICK LMS-511 二维激光扫描传感器和步进电机，设计并实现了一种自动化低成本地面激光扫描仪，命名为 BEE（由北京林业大学电子工程系开发），可对森林树木进行三维扫描。BEE 扫描仪及其配套软件专为森林清查而设计。具体软件是为了顺利控制 BEE 扫描仪并获取数据而开发的，包括角度数据、距离数据和强度数据，BEE 扫描仪获取的数据可处理成点云数据、距离图和强度图。基于点云数据，通过对样地中单扫描的单个切片进行树木检测，为每个检测到的树木拟合局部地面平面。然后，利用特定软件自动估算胸径（DBH）、树高和树位。本研究在位于北京市海淀区的人工银杏林内进行了 BEE 扫描仪的实验，共选择了 4 个 10 m×10 m 的正方形样地。BEE 扫描仪在这 4 个样地中进行扫描，分别获取单扫描数据。对 4 个样地中的树木的 DBH、树高和树位进行了估算和分析。为了进行比较，还在这 4 个样地中采集了手动测量数据。4 个样地的树干检测率均为 92.75%；DBH 估算的均方根误差为 1.27 cm；树高估算的均方根误差为 0.24 m；树位估算与实际位置相符。该扫描仪还在九峰森林公园的天然林进行了测试。扫描了两个半径为 5 米的样地。在平地样地中检测到 11 棵树并估算了 DBH。但由于地面起伏，另一个样地的树木检测失败。实验结果表明，BEE 扫描仪可以有效地估算人工林树木的结构参数，在森林清查的实际应用中具有良好的潜力。
