A novel strategy for improving canopy nitrogen density retrieval by deciphering saturation effects and vertical heterogeneity - Hongye Yang; Bo Ming; Chenwei Nie; Dayun Feng; Kexin Gao; Shang Gao; Jun Xue; Guoqiang Zhang; Peng Hou; Ruizhi Xie; Zhenhai Li; Xiuliang Jin; et al. (Computers and Electronics in Agriculture, 2026)