木材のカスケード利用に向けた可搬型3次元レーザスキャナによる木材資源量算定: 長野県北信エリアのスギの事例

摘要

本論文では、長野県信濃町のスギ林にて、可搬型3次元レーザスキャナの計測と、実測による精度誤差の検証を行い、実務への適用可能性について検討、またカスケード利用や木材調達への効果を検証し、以下の結論を得た。①3次元レーザスキャナによる樹幹直径の計測の平均差異は、1.84cmであり、流通上2cm刻みで取引されており、製材用丸太の資源量把握としては有効である。また樹髙についても、建築用材となる根元の部分からの計測はできており、建築用材の調達において、スキャナによる計測は実用可能である。%Computerization and sharing of information regarding forest resources and timber distribution are important topics for sustainable forest management. Based on the example of Japanese cedars in Nagano prefecture this research study investigates precision and accuracy problems encountered when using portable 3D laser scanners for computerization of information on forests, therefore considering possible future forest management methods. The discrepancy between the scan-derived measurement and the manual measurement (by measuring each tree separately) as well as the technical aspect of both methods were evaluated. The scanner proved to be precise in measuring trunk diameter, tree height, and tree position. When all the parts of branches and leaves can be measured by a single 3D laser scanner, a significant correlation is seen between the number of reflection points from branches and leaves and their weight. The following regression equation was obtained for this case. However, the validity of the equation cannot be confirmed because of the small quantity of collected data (with only ten samples being investigated). It is assumed that more measurement data collected continuously in the future will enhance the accuracy and validity of the equation, which can be useful for accurate estimation of the amount of tree canopy.