Parametric Description And Meshing Algorithm For The Surface Of Spatial Structure

Spatial structure presents colorful shape surface, which can be classified as function surface and free surface. Free surface has been applied widely in spatial structure due to its vivid shape. However, modeling of free surface is difficult because it has no analytic expression. This paper mainly researched on parametric description and meshing algorithm for the free surface of spatial structure with the program development.First, development and actuality of surface modeling techniques in spatial structure were introduced, and some problems were also expounded.Research on free surface is mature in Computer Aided Geometric Design (CAGD). Some of basic theories and concepts in CAGD were presented. Based on the existing research finding, algorithm of Bicubic B-Spline Interpolation Surface was expounded as theoretical basis of this paper.Surface in Spatial Lattice Structure is comprised of grids. Drawing lessons from Finite Element Method (FEM), reflection mesh method base on reinterpolation was proposed and applied to the surface modeling discussing in this paper. Besides, grids with different types were evaluated, using the grid quality criterion.The shape of mussel is pretty and with good mechanical property. But it is hard to be generalized, because it is difficult for model building due to its complex shape and no professional software can be used. Considering features of spatial structure, the shape of mussel was studied using techniques of free surface modeling and mesh method with suitable grid type.Skinning is a common method of surface definition in the CAD system. In this paper, algorithm of skinning was studied and improved for the further application in surface reconstruction.In order to have a practical surface model, shelly surface can be optimized with energy method.A surface modeling program orient to spatial structure was developed. In this program, the surface modeling methods above were demonstrated by some examples.