摘要

By the degree elevation-based method of approximating rational curves and surfaces using polynomial curves and surfaces, a new effective approach to construct rational Be´zier harmonic surfaces over rectangular or triangular domain is presented. First, rational Be´zier curves, given as the boundaries, are transferred into some approximate polynomial curves, according to which a polynomial harmonic surface T then can be generated by using Monterde's method. On the other hand, the unknown rational Be´zier harmonic surface R with the given rational boundary curves is transferred into an approximate polynomial surface N, whose degree is the same as that of T, so that the control points of N can be expressed as a function of both the weights and control points of R. Comparing T with N, by solving a minimizing problem with nonlinear object function, the rational harmonic surface R can finally be obtained. Several pragmatic illustrations are presented to testify validity of this algorithm.

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