Fei Liang, Xidian University, Shaanxi, China; Aerial Photography and Remote Sensing Group Co.Ltd. Xi’an 710199, China, China; Ruizhi Yang, Xidian University, Shaanxi, China, China; Zhengyao Wang, Aerial Photography and Remote Sensing Group Co.Ltd. Xi’an 710199, China, China; Yang Hu, Dong Zhao, Shuang Wang, Xidian University, Shaanxi, China, China