Table 5.
Results of the PLSR models of the heavy metal content prediction using the field VNIR-SWIR data and given different preprocessing methods.
| Heavy Metal | Treatment | Calibration Set (56 samples) |
Validation Set (19 samples) |
RPIQ (test-set cal) | VL | ||||
|---|---|---|---|---|---|---|---|---|---|
| R2cv | RMSECV | RPD | R2 | RMSEval | RPD | ||||
| Pb (mg/kg) | Reflectance | 0.45 | 8367.8 | 1.12 | 0.04 | 8390.32 | 1.05 | 1.22 | 6 |
| SNV | 0.38 | 8774.55 | 1.05 | -0.02 | 8672.98 | 1.02 | 1.12 | 5 | |
| MSC | 0.41 | 8545.45 | 1.1 | -0.33 | 9887.97 | 1.01 | 1.29 | 5 | |
| Zn (mg/kg) | Reflectance | 0.79 | 10915.96 | 2.11 | 0.56 | 15050.12 | 1.54 | 3.47 | 9 |
| SNV | 0.82 | 9963.97 | 2.29 | 0.64 | 13610.01 | 1.71 | 3.65 | 11 | |
| MSC | 0.82 | 9845.26 | 2.29 | 0.54 | 15306.2 | 1.52 | 3.59 | 9 | |
| Cd (ppm) | Reflectance | 0.59 | 130.23 | 1.34 | 0.08 | 141.29 | 1.07 | 1.38 | 3 |
| SNV | 0.49 | 143.19 | 1.12 | 0.54 | 100.5 | 1.51 | 1.45 | 2 | |
| MSC | 0.5 | 140.84 | 1.13 | 0.46 | 108.36 | 1.4 | 1.45 | 2 | |