Piecewise-smooth Subdivision Surfaces with Normal Control

Henning Biermann,     Adi Levin,     Denis Zorin

Abstract

In this paper we introduce improved rules for Catmull-Clark and Loop subdivision that overcome several problems with the original schemes, namely, lack of smoothness at extraordinary boundary vertices and folds near concave corners. In addition, our approach to rule modification allows the generation of surfaces with prescribed normal, both on the boundary and in the interior, which considerably improves control of the shape of surfaces.

• Software: our reference implementation is available as source code unter the GNU public license.
• Some additional images are available here.