Research On Surface Fitting And Optimization Method Based On NURBS

With the rapid development of modern industrialization,obtain high-quality NURBS fitting surface quickly,accurately,and efficiently is the key to surface reconstruction in reverse engineering.Therefore,the surface fitting and optimization methods of NURBS should be further studied.In this paper,the fitting and optimization methods of quadric surface and free-form surface are studied.And simulation models are built for experiment and analysis.Firstly,the method of NURBS surface fitting is described in detail.Based on the definition and property of NURBS surface,the concrete realization of control points solving process and surface shape modification process are given.Providing theoretical foundations for presentation and improvement of the subsequent surface fitting and optimization methods.Secondly,aiming at the NURBS fitting problems of low accuracy and large amount of computation caused by too little or too many control points,the NURBS optimal representation method of quadratic surface is described emphatically.According to the shape characteristics of the quadratic surface,the parametric direction of the u?v is determined to reconstruct the surface.Using the absolute value of difference value and root mean square error,the error quantitative analysis of each reconstructed surface fitted by the number of different control points is carried out.Combined with quantitative analysis curve and program running time relation curve to solve the selection range of optimal control points for quadratic surface fitting.And the optimization effect of the NURBS optimization method of quadratic surface is analyzed.Again,a NURBS surface reconstruction algorithm based on fractional Fourier transform is constructed.The elevation image is obtained by grid processing of point cloud data.The feature extraction of elevation image sequences is carried out by using fractional Fourier transform.Based on the initial fitting surface,the fractional-order Fourier transform filtering and back-inserting node method is used to obtain the optimal reconstructed surface.Finally,an experimental platform is set up to obtain the point cloud data of the real model.The actual point cloud data and simulation model are experimented and processed by MATLAB.Comparing with other methods,the correctness and feasibility of surface fitting and surface optimization methods based on NURBS are proved.