1. State Key Laboratory of CAD&CG; Zhejiang University; Hangzhou, 310058 China
2. Virtual Reality and Interactive Technique Institute; East China Jiaotong University; China
3. Department of Computer Science; University of Houston; Houston, TX USA
4. LINCTEX; Shanghai, 200331 China
5. International Design Institute; Zhejiang University; Hangzhou, 310058 China