Fig. 9

Comparison of precision results based on 126 models. Gray is the accuracy of CODcr modeled based on different spectral features (first-order derivative, second-order derivative, third-order derivative, logarithmic first-order derivative, logarithmic second-order derivative, logarithmic third-order derivative and 25 SCV). Red is the accuracy of NH3-N modeled based on different spectral features. Blue is the accuracy of TP modeled based on different spectral features. Green is the accuracy of TN modeled based on different spectral features. Purple is the accuracy of pH modeled based on different spectral features. Yellow is the accuracy of Chl modeled based on different spectral features.