Verification of accuracy for forest mensuration using a terrestrial laser scanner
2018
Kawakita, N. (Kyoto Prefectural University, Kyoto (Japan). Graduate school of Life and Environmental Sciences) | Nagashima, K. | Tanaka, K.
The objective of this study was to analyse the measurement error of a terrestrial laser scanner (TLS, FARO Laser Scanner Focus 3D X 330) and the factors affecting them at two different forest stands (Cryptomeria japonica, Chamaecyparis obtuse) -the 100-yr old stand at Ono University forest and the 45-yr old stand at Hiyoshi-cho, Kyoto prefecture. Diameter at breast height (DBH) and height data obtained by a Digital Forest (a software analyzing point cloud data) were compared with field data for each stand. The influence of five factors-distance from the scanner, tree size (DBH and height), slope angle, tree position (upper side or underside of the TLS), and number of scanners visible from each tree-on DBH and height errors was investigated by a non-parametric test. The factors affecting the measurement error were detected by multiple regression analyses. The DBH and height errors for the Ono stand exceeded those for the Hiyoshi stand. The tree size (both DBH and height) had the largest impact on the DBH and height errors at the Ono stand. At the Hiyoshi stand, the distance from the TLS was detected as the factor having the largest effect on the DBH error, and slope angle was detected as the factor affecting the height error. Consequently, the tree size and the location at which the TLS is installed appear to be important factors affecting the error, especially in a mature stand like the Ono stand. Our result indicates that the optimum distance between the TLS locations is less than 15m.
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