地面光達應用於林木競爭之研究

Assessing Measures of Tree Competition by Using Ground-based LiDAR

魏浚紘(Chun-Hung Wei) ； 陳朝圳(Chaur-Tzuhn Chen) ； 彭炳勳(Bing-Syun Peng) ； 李崇誠(Chung-Cheng Lee) ； 陳建璋(Jan-Chang Chen)

《航測及遙測學刊》 16卷4期 (2013/01) Pp. 279-287

https://doi.org/10.6574/JPRS.2013.16(4).4

摘要

近年來，隨著遙測技術精進，已有許多繪製立木位置圖之方式，多半以二維空間影像來獲得立木位置，但後續應用上會局限於二維空間資訊，無法進一步深入探討。本研究利用地面光達技術，進行森林地區點雲掃瞄，透過三維空間點雲資訊獲取林木資訊與繪製立木位置圖，藉由立木位置圖與林木資訊，進一步探討林木間相互競爭之關係。本研究以六龜地區之紅檜人工林為研究範圍，並透過地面光達繪製之立木空間位置圖進行林木競爭指數計算，評估林木間相互競爭後，其生長狀態空間分布特性。透過樣區中立木之實測值與地面光達點雲資訊所獲得之立木位置相比較，結果顯示水平誤差絕對值0.1m以下共有13株（28.26%）；垂直誤差絕對值0.1m以下共有15株（32.61%），而水平誤差絕對值0.5m以下共有35株（76.09%）；垂直誤差絕對值0.5 m以下共有38株（82.61%）。透過地面光達點雲亦可得到準確度高之每木胸徑，其R^2為0.9685，但掃瞄時必須注意掃瞄點位置與數量，方能得到點雲資訊較為足夠之光達點雲。藉由地面光達資訊之立木距離與胸徑資訊即可計算林木競爭指數，其R^2為0.9905。

關鍵字

三維雷射掃瞄 ； 地理資訊系統 ； 林木位置圖 ； 競爭指數

並列摘要

Recently, remote sensing technology has progressed to permit quicker access to individual tree positions using two-dimensional (2D) information. Therefore, insufficient 2D information has led to subsequent limited applications of the technology. We used ground-based LiDAR technology to map three-dimensional (3D) individual tree positions in the Liukuei forest. The 3D laser scanner obtained highly accurate scans of cloud data, and provided basic information on individual tree spatial distribution. We compared different data collections of tree spatial distribution and forest measurement characteristics from the original field survey using the LiDAR technique. The results showed that the absolute value of horizontal error of less than 0.1 m is 28.26% (13 trees) and vertical error of less than 0.1 m is 32.61% (15 trees). In addition, the absolute value of horizontal error and vertical error of less than 0.5 m were 76.09% (35 trees) and 82.61% (38 trees), respectively. However, there was strong correlation between the LiDAR DBH and field DBH (coefficient of determination R^2=0.9685). The LiDAR detection location and an increase in the detecting quantity could obtain sufficient point cloud data. The linear correlation R^2 value of the field measured and LiDAR detection was 0.9905, which showed that 3D laser scanning technology provided effective quantification data to reconstruct a tree competition index and tree growth model in a forest ecosystem.

並列關鍵字

3D laser scanning ； geographical information system ； individual tree location map ； competition index