1. School of Artificial Intelligence, Optics and Electronics, Northwestern Polytechnical University, Xi’an, China
2. School of Computer Science and Technology, Anhui Provincial Key Laboratory of Multimodal Cognitive Computation, Anhui University, Hefei, China
3. National Engineering Laboratory for Visual Information Processing and Applications and the Institute of Artificial Intelligence and Robotics, Xi’an Jiaotong University, Xi’an, China