Funding for this research was provided by:
the NSF of China (61305087, 61673354)
the NSF of China (61672474, 61501412)
Open Research Project of The Hubei Key Laboratory of Intelligent Geo-Information Processing (KLIGIP201603, KLIGIP201607)
US National Science Foundation Award (1626586)
Article History
Received: 17 December 2016
Revised: 10 February 2017
Accepted: 25 March 2017
First Online: 1 April 2017