Fig. 1. Location of the study area and experimental design of winter wheat

Fig. 2. The curve of root mean square error(n=32)

Fig. 3. The determination coefficient and root mean square error of vegetation indexes and LAI (n=32)
(a): R² for LAI and NDSI; (b): RMSE for LAI and NDSI; (c): R² for LAI and RSI; (d): RMSE for LAI and RSI; (e): R² for LAI and SSI; (f): RMSE for LAI and SSI

Fig. 4. Results of LAI models with different band combinations (n=16)
(a): VI_OIF_SVR; (b): VI_OIF_PLSR; (c): VI_OIF_RFR; (d): VI_SPA_SVR; (e): VI_SPA_PLSR; (f): VI_SPA_RFR; (g): VI_E_SVR; (h): VI_E_PLSR; (i): VI_E_RFR; (j): VI_F_SVR; (k): VI_F_PLSR; (l): VI_F_RFR

Fig. 5. Spatial distribution map of LAI in winter wheat