Fig. 1. The study area and distribution of sampling points
(a): RGB true color image of Fukang city and study area using Gaofen-1; (b): Sampling points

Fig. 2. UAV operation and UAV-based hyperspectral sensor

Fig. 3. Descriptive chart of the sample sets

Fig. 4. Hyperspectral images after FOD processing
(a): Hyperspectral image cube; (b)—(u): Processing results of 0.1 to 2 orders

Fig. 5. Spectral preprocessed by different FOD

Fig. 6. The correlation coefficient between band and SMC under different FOD pretreatments
(a): Heatmap; (b): Maximum correlation coefficient

Fig. 7. Scatter plot of measured SMC and estimated SMC

Fig. 8. SMC spatial distribution under the optimal model

Fig. 9. Bands importance under different FOD pretreatment