原木形状の自動計測法に関する研究 (第3報) : 光切断法による丸太形状の3次元的計測

Abstract

丸太の3次元形状を自動計測するため, 定速で移動している丸太の横断面 (円と仮定) を光切断法を用いた計測ビデオシステムによって一定間隔毎に求める方法を開発し, その計測精度, 問題点等について検討した。表面が比較的平滑で断面が円に近い丸太については, 軸方向における径の変化, 曲がり, 材積等を十分把握することができた。しかし断面が楕円状の場合や節などによる表面の凹凸が著しい場合には, 断面全周のうちの約150°の範囲の輪郭のみから全断面に適合する円を推定する本方法では誤差が大きくなる。

A new method was developed to measure automatically the three-dimensional shape of a log. The cross-seetional shape of a log was assumed to be circular, and the diameter and the coordinate of the center of the circle were measured by the light section method using the measuring video system at a constant interval along the log axis (Figs. 1 and 2). When a log had a relatively smooth surface and its cross section could be considered to be circular, the three dimensional characteristics of the log such as the volume, the curvature, the deviation in diameter along the axis, etc, were well grasped by the present method (Figs. 7-10, Table). The accuracy of the measurement, however, decreased when the cross section of the log was rather oval than circular or the surfce of the log was noticeably rough, e. g. due to a lot of knots, because in the present method the log was measured from only one direction (Fig. 1).