Quantitative Realization of Spiral Motions Observed in Principal Components of "Jiuta-Mai" Japanese Classical Dance

〈Summary〉 A unique feature of Jiuta-Mai in Japanese classical dance is a set of spiral movements propagated gradually from one part to another adjacent part of the body. In order to quantitatively realize the existence of spiral movement, analysis of a 3 dimensional (3D) time series of a dance motion performed by two master Japanese classical dancers was carried out. It revealed that the transformation of original 3D coordinates into a local coordinate system consisting of principal components, was effective. The first principal component represented the overall direction of body motion, and the spiral motions were clearly visualized through cyclic curves appearing in the second and third components, perpendicular to the first component.