Research On Upper Computer Aided Design

This article discussed the technology of upper computer aided design, and developed an upper design system based on Rhino platform. This scheme can fully use the resources of Rhino platform, so can greatly reduce the system development difficulty; and this system can help the shoemaking enterprise to enhance the working efficiency, and to promote the quality of its product, so it has enormous utility value.At first, the article summarized the technical background of shoe-CAD system and the current situation of studies about this system both at home and abroad. Then simply introduced the survey of the Rhino platform and the plug-in developing technology and method based on the platform.This article in detail discussed the theory and related algorithms of parameter curve, which was the foundation to develop the system. The content of this part included the general theory of parameter curve,Bézier curve theory and its algorithms, B-spline curve theory and its algorithms, NURBS curve theory and its algorithms. This article discussed the B-spline curve algorithms with emphasis, including the computation algorithm of curve points and curve derivative vectors of all degrees, knot insertion algorithm, curve division algorithm, the computation of curve bounding box, the anti-computation algorithm of Non-uniform B-spline curve,the approximation algorithm of B-spline curve using the Least Squares Method under a given precision and so on. This article proposed the concept of the minimum closed loop for the first time, and induced its two nature, and proposed a recognition algorithm of minimum closed loops from a parameter curve set according to these two nature; and independently educed a formula for directly calculating the coefficient matrix of three degree Non-uniform B-spline curve, proposed a fast algorithm for curve subdivision, improved the algorithm for calculating curve intersection points.This article finally in detail introduced the basic realization process of the system, including three parts: the acquisition of primitive upper data, the design of uppers, the output of upper data. The realization of several important crafts for upper design was introduced, including expanding the three-dimensional surface of last to planar surface, converting a bitmap of uppers to a vectorgraph, cutting the total upper graph to several independent uppers, processing interspacial angle of upper, scaling-up and scaling-down uppers and so on. Some design tools were also introduced, including a curve edit tool which can modify the curve but not change the length of curve and maintain the shape...