Tian Xie, Beijing Normal University, China; Xuewei Hu, Beijing Institute of Surveying and Mapping, China; Shiyu Chen, Columbia University, United States; Hailan Jiang, Hefei University of Technology, China; Ronghai Hu, University of Chinese Academy of Sciences, China; Fan Li, Xihan Mu, Donghui Xie, Guangjian Yan, Beijing Normal University, China