Fig. 5
From: Estimation of soil free Iron content using spectral reflectance and machine learning algorithms
Correlation coefficient of soil free content and the original and CR, SNV, and FD spectra (a), and explained variance for principal components (PCs) output by a PCA applied to original spectra and CR, SNV, and FD spectra (b). In (a) plot, bolded lines indicate a correlation coefficient value is greater than 0.400. n = 540. In (b) plot, violet, red, green, and blue line represent original spectra and CR, SNV, and FD spectra. FD first derivative, SNV standard normal variate, CR continuum removed.
