A novel approach to free-form 3D curve and surface sketching for conceptual styling

In the CAD/CAS field, the increasing domination of splinebased graphic objects has driven a great attention to methods focusing on the management of free-form curves. These methods range from basic manipulation of control points to more sophisticated direct manipulation techniques by using tangency or curvature constraints. However they are not suitable for the earlier conceptual stage where quick brainstorming illustrations and stepwise refinements are required. In this paper we present a method, which automatically reconstructs the designer’s free-form 3D curve through recognizing his design “intention”. This algorithm automatically extracts the relevant control points through dynamic sampling mechanism. Furthermore, we apply these approximated curves to create freeform surfaces. We also introduce a touch-enabled global and local modification method which is capable of effectively obtain quality and accuracy deformation results. The method has been tested with various types of sketches which are rendered in 3D scene environment.