Fig. 1

   a Location of the study area in Hebei, China b An overview of the study site and three soybean plots and c an RGB map of the experimental field, and the setup of 12 GCPs and reference panels
   a Location of the study area in Hebei, China b An overview of the study site and three soybean plots and c an RGB map of the experimental field, and the setup of 12 GCPs and reference panels