The Research And Software Development Of Three-Dimensional Surface Modeling And Editing

There are more and more complex surfaces since the complication of the product geometry shape, which lead to the higher status of surface modeling part in CAD/CAM. JHSolid is a domestic three-dimensional CAD system which developed by using the foreign modeling core Parasolid. The solid modeling aspect shows its simple and easy to use style, however this system doesn't have surface modeling function now. This thesis is to fetch up JHSolid's limitation in surface modeling field, try to develop some popular surface modeling functions prepare for the next software's updating.Surface modeling is a difficulty in three-dimensional CAD field, which involved CAGD mathematic theory, computer graphics, software develop method and so on. The preparation include the studying of relative theory knowledge, the software develop method, how to use the Parasolid modeling core and OpenGL graphics tool and familiar with the frame of JHSolid. After the preparation, the function developed consists of the following three parts: free-form surface modeling, sweeping and lofting and surface editing.The free-form modeling part use B-spline method. Some excellent characteristics of B-spline surface make it a popular tool in modern free-form surface modeling. The constructing, transforming and knot adding of B-surface function is developed in the part of free-form surface modeling, and the input of operation point matrix is a key problem in this part. Four detailed functions were included in the sweeping and lofting: extending, spinning, sweeping and lofting. Knot match arithmetic is proposed in lofting. The theoretical background of sweeping and lofting is researched and the results of sweeping and lofting in Parasolid are concluded in this part. The surface editing comprises of surface trimming, surface connecting, surface offsetting, surface extension, and surface section. The surface connecting part includes surface sewing, surface patching up and surface blending. This part not only achieves the surface editing itself but also the solid editing by surface.All of these functions in the three parts have passed the elementary test, which prove the feasibility of the methods.