1. School of Mathematics and Computer Science, Zhejiang A&F University, Hangzhou, China
2. Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology, Zhejiang A&F University, Hangzhou, China
3. College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
4. State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou, China