Funding for this research was provided by:
National Natural Science Foundation of China (61502402)
Fundamental Research Funds for the Central Universities (20720180073)
state key laboratory of virtual reality technology and systems of China (BUAA-VR-15KF-09)
Xiamen University (20720150081)
Article History
Received: 29 May 2018
First Online: 14 January 2019