Nurbs Surface Reconstruction In Reverse Engineering

Many existing surface reconstruction methods usually separate surface modeling from the characteristics of data points, which not only increases the burden of pre-processing, but also lead to potential loss of important features of the model. This paper puts forward a reconstruct method accordingly based on different features of data set.For the data set that carries scanning curves information (such as from CMM), a method is implemented to establishing the topological relations among the points, simplifying the complex pre-processing task - data processing.During surface construction, an algorithm of surface interpolation is achieved. The knots vectors are established, via Accumulative Chord Length method. So the precise surface can be attained.Fast B-spline evaluation algorithm is designed. By performing symbolic manipulation based on the iterative functions, we first express a B-spline basis function as piecewise polynomials through coefficient calculation. In such a way, the final evaluations become evaluations on polynomials, which requires much less computer time.IGES criterion is used for data exchange. IGES reading and writing engine is designed. COM technology is used for software reusing.