INTERACTIVE CONSTRUCTION OF B-SPLINE APPROXIMATIONS OF SURFACES AND A TESSELATION ALGORITHM FOR THE REPRESENTATION OF TRIMMED SURFACES FOR USE IN NUMERICAL GRID GENERATION

摘要

Grid generation is concerned with discretizing surfaces and surrounding volumes in three-dimensional space. Often, the originally given surfaces contain errors, such as gaps between surfaces, intersecting surfaces, or overlapping surfaces. A method is presented for the correction of such errors. The method replaces a faulty, discontinuous geometry by a new set of continuous surface patches. The second part of this paper deals with the representation of trimmed surfaces, i.e., surfaces with holes. Many applications, including surface rendering and grid generation, require an approximation of the complement of the part of a trimmed surface that is ''cut out'' by the holes. An approach for decomposing the valid part of a trimmed surface into a set of four-sided surfaces (without holes) is discussed. [References: 11]