Based On The Cb Spline Catmull-clark Subdivision Surface Modeling Techniques

Although the subdivision methods especially about Catmull-Clark subdivision surfaces become more and more popular in the research of Computer Graphics and achieve great success, the surface modeling in Engineering was still based on NURBS surface in recent years and developed slowly. The reason of this phenomenon is that Catmull-Clark based on cubic uniform Bsplines can't solve the problem of precise representation of standard analytic shapes such as circle, conies. However, through researching the subdivision method of C-Bsplines, this paper concludes a new Catmull-Clark subdivision algorithm based on C-Bsplines. This new method not only solves the problem of the precise representation of standard analytic shapes, but also overcomes the difficulty of generating surfaces on arbitrary topological meshes faced by NURBS. The main contents of this paper are as following:Firstly, the article introduces and analyzes the characteristics and technology of subdivision methods. It discusses completely the basic principles and algorithm of the some subdivision modes such as Catmull-Cark, Do-Sabin, Loop mode. And then, their characteristics are compared and the advantages of Catmull-Clark mode in subdivision are pointed outFurther more, the curves and surfaces modeling with C-Bsplines are systematically studied. After the analysis of C-curve, the characteristics of C-Bsplines are studied. And this paper presents methods to change the shape parameters and control points and successfully designs circles and ellipses with C-Bsplines. Meanwhile, some results are applied into surfaces with following by constructing general cylinders, ruled surfaces, surfaces of revolutions and so on.Finally, using characteristics of the subdivision algorithm, this article applies it hi Catmull-Clark subdivision surfaces and advances a new algorithm hi extraordinary points on arbitrary topological meshes, and then puts forward a new kind of Catmull-Clark subdivision surfaces based on C-Bsplines. In this way, the shapes of the surfaces can be adjusted and the standard analytic shapes such as cylinders can be constructed. Moreover, a software system is designed with Visual C++ and OpenGL in order to research and experiment deeply.