Funding for this research was provided by:
National Natural Science Foundation of China (41601501, 41271135)
Natural Science Found for Colleges and Universities of Jiangsu Province (16KJD420001)
Huaian Key Laboratory of Geographic Information Technology and Applications (HAP201405)
Article History
Received: 31 October 2017
Accepted: 24 April 2018
First Online: 14 May 2018