1 | College of Surveying and Geo-informatics, North China University of Water Resources and Electric Power,
Zhengzhou 450046, China |
2 | College of Geography and Environmental Science, Henan University, Kaifeng 475004, China |
3 | Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions (Henan University),
Ministry of Education, Kaifeng 475004, China |