1. School of Optoelectronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China
2. Research Center of Intelligent Equipment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
3. Key Laboratory of Agricultural Sensors, Ministry of Agriculture and Rural Affairs, P. R. China, Beijing 100097, China
4. College of Engineering and Technology, Southwest University, Chongqing 400715, China