## 3 Results and Analysis
### Influence of Spatial Resolution on LAI Inversion  
Spatial resolution influenced the LAI inversions from all the different sensors: the value ranges and accuracies of the LAI inversions both decreased with decreasing spatial resolution (Figures 4 and 5). The spatial representativeness of the LAI field measurements was first assessed by the RAE and CS, according to the methods in Section 3.3 to determine the differences between the LAI inversions from the NDVI-LAI relationships for ZY-3 MUX, GF-1 WFV, and HJ-1 CCD with different spatial resolutions. The LAI inversions from ZY-3 MUX, GF-1 WFV, and HJ-1 CCD were compared with the different spatial representativeness of LAI field measurements, and the results are shown in Figure 6. The performance of the LAI inversions from ZY-3 MUX, GF-1 WFV, and HJ-1 CCD using the LAI field measurements with high spatial representativeness was higher than that obtained using measurements with low spatial representativeness. The LAI inversions using measurements of low spatial resolution exhibited various degrees of underestimation. However, although the performance of the LAI inversions using the LAI field measurements with high spatial representativeness appears to be better in Figure 6a, the LAI inversions for GF-1 WFV and HJ-1 CCD were systematically more underestimated than were those for ZY-3 MUX. It is possible that the size of the pixels of the ZY-3 MUX data was closer to the actual surface. However, the lower spatial resolution of the GF-1 WFV and HJ-1 CCD data recorded more comprehensive information about the surface objects; thus, the vegetation signal was weakened. Therefore, the accuracies of the LAI inversions from the lower-spatial-resolution data were generally lower than those of the higher- spatial-resolution data. Figure 5: Comparisons of the LAI inversions with the field measurements for ZY-3 MUX (**a**,**d**), GF-1 WFV (**b**,**e**), and HJ-1 CCD (**c**,**f**). In addition, this study extracted a 3 \(\times\) 3 km\({}^{2}\) range of LAI inversions from the NDVI-LAI relationships to compare the accuracy of LAI inversions among ZY-3 MUX, GF-1 WFV, and HJ-1 CCD at a consistent spatial resolution. The LAI result of ZY-3 MUX was up-scaled to 16 m and 30 m spatial resolution, and the LAI result of GF-1 WFV was up-scaled to 30 m spatial resolution using the upscaling method described in Section 3.3. The up-scaled LAI inversions with 30 m spatial resolution from ZY-3 MUX and GF-1 WFV were compared with the LAI inversion from HJ-1 CCD (Figure 7). The results indicated that the distribution patterns of the LAI inversions were consistent, and that there were higher LAI values in the top left corner of the image near cropland and lower LAI values near roads and in residential areas. However, the LAI inversions that were up-scaled from higher spatial resolution (e.g., ZY-3 MUX and GF-1 WFV) reflected more detail than did the HJ-1 CCD inversion at the same 30 m spatial resolution. The pixels that were extracted from the LAI inversions in the 3 \(\times\) 3 km\({}^{2}\) area were used to further analyze the differences among the three LAI inversions at the same spatial resolution. The pixels in the subregion were separated into pure pixels with uniform surface types and mixed pixels with different surface types, including different vegetation types, roads, or residential areas. The relationships between the LAI inversions from ZY-3 MUX data that were up-scaled to 16 m spatial resolution and those from GF-1 WFV data and the relationships between the LAI inversions from the ZY-3 MUX or  
Figure 6: Validation of the LAI inversions from ZY-3 MUX, GF-1 WFV, and HJ-1 CCD using field data with high spatial representativeness (**a**) and low spatial representativeness (**b**). Figure 7: LAI inversions up-scaled to 30 m spatial resolution from ZY-3 MUX (**a**), GF-1 WFV (**b**), and HJ-1 CCD (**c**). GF-1 WFV data that were up-scaled to 30 m spatial resolution and the LAI inversions from HJ-1 CCD data are shown in Figure 8, for both the pure (blue dots) and mixed (red dots) pixels.