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Proceedings of CAD'15, 2015, 286-290
Retaining Circular Features on Deforming Subdivision Surface
Abstract. In engineering design, designers are always facing the problem of modify existing design to fulfill new application requirements. In this process, existing object shapes may have to be deformed while special shape features are retained by including constraints in the model based on the application requirements. Retaining features while modifying regular objects to freeform objects is always a challenging problem for existing engineering CAD software. Most of the CAD software use CSG-tree and NURBS surface representation, which is effective in modeling regular engineering objects and is accurate in describing the dimension of features. However CSG-tree is inefficient in representing freeform objects. NURBS surfaces are essentially four-sided, which limits user to model shapes with general topology. Subdivision surface is a better candidate than NURBS when it comes to representing freeform objects. It is capable of generating smooth surface with irregular topology, allowing user to model freeform object efficiently. Multi-resolution editing is also supported when using subdivision surface. Editing can be performed on coarse initial mesh and propagate to fine mesh, saving time and complexity for mesh editing. With the above advantages, subdivision surface is widely used in the animation industry. However, in engineering design, subdivision surface is usually not adopted as modeling primitives. This is mainly due to two reasons: 1. Subdivision surface cannot be expressed explicitly and 2. The instability caused by extraordinary vertices.
Keywords. Constrained deformation, Subdivision surface, Object modelling