An approach for the integration of subdivision surfaces in a hybrid CAD system

The project NIIT4CAD aims to effectively integrate subdivision surfaces in a computer-aided design modeling environment. To this end, a new CAD system paradigm with an extensible geometric kernel is introduced, where any new shape description can be integrated through the two successive steps of parameterization and evaluation, and a hybrid boundary representation is used to easily handle different kinds of shapes. To overcome the irregular behavior of subdivision surfaces in the neighborhood of extraordinary points, the limit surface of the subdivision scheme is locally modified, so as to tune the analytic properties without affecting its geometric shape.