Advanced curve and surface design in CAD system using STEP

In this paper, methods and techniques newly developed are presented for high-quality curve and surface modeling in CAD systems. The data structure and data exchange are based on STEP, the international standard for external representation of product data. While accurate algebraic representation is used for lower degree curves and surfaces, NURBS (Nonuniform Rational Bspline Surface) representation is adopted as a unified approach to advanced curve and surface design. We thus have both advantages for accurate shape processing in CAD/CAM and high-quality design of shapes with free-form surfaces.<
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