Abstract

Interactive deformation of surface models, which consist of quadrilateral (regular) and non-quadrilateral (irregular) surface patches, arises in many applications of computer animation and computer aided product design. Usually a model is mostly covered by regular patches such as Bézier or B-spline patches and the remaining areas are blended by irregular patches. However, the presence of irregular surface patches has posed a difficulty in surface deformation. Although regular patches can be easily deformed, the deformation of an irregular patch, however, has proven much trickier. This is made worse by having to maintain the smoothness conditions between regular and irregular patches during the process of deformation. By inserting extra control points, we have proposed a technique for the deformation of irregular surface patches. By setting continuity conditions as constraints, we also allow a surface model of an arbitrary topology, consisting of both regular and irregular surface patches, to be deformed smoothly.