FURUKAWA Susumu YAMANASHI UNIVERSITY,MECHANICAL SYSTEM ENGINEERING,PROFESSOR, 工学部, 教授 (40020408)
HIGASHI Masatake TOYOTA TECHNOLOGICAL INSTITUTE,MECHANICAL SYSTEM ENGINEERING,PROFESSOR, 工学部, 教授 (70189752)
|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,200,000 (Direct Cost : ¥1,200,000)
The method is proposed for modeling aesthetic product-shape by extracting characteristic lines from its three-dimensionally measured data. Measured data are divided into some segments based on rough information of characteristic parts and implicit specifications in the data and surfaces are least-square-fitted to each segment. Then, surfaces of increased degree polynomial are fitted to data within decreased distance from the previous surfaces. This stepwise surface-fitting process extracts characteristic lines precisely as intersection lines of pairs of surfaces.
After extracting characteristic lines, we have to express a surface without any distortion of highlight lines and reflected images. Therefore, we developed the following curve design methods that specify and control shape of curves by intrinsic geometric quantities familiar with designers, such as arclength, tangent and curvature. We first derived an interpolating clothoidal spline curve, and second, extended it to an interpolant with quadratic B2-spline curvature function of arclength, and then developed a composite curve of these. Finally, we introduced an interpolant composed of logarithmic spirals, whose radius of curvature is piecewise linear with respect to arclength. In these curves, we are able to design an aesthetic smooth curve directly from desired profile of (radius of) curvature by well-known Bezier techniques not in curve space but in curvature space.