A Spectral Transfer Function to Harmonize Existing Soil Spectral Libraries Generated by Different Protocols

Table 1

Datasets per stage (see text for a detailed explanation).

Stage	Reference number	Datasets
New measurements for the rectification group	1	Processed with ISS
	2	Without ISS and without TF processing
	3	With TFs1 processing
Old–original measurements of the rectification group	4	Without ISS and without TF processing
	5	With TFs1 processing, based on the new spectral measurements of the rectification groups (using the new spectral measurements for the TF calibration stage and predicting the post-ISS rectification status of the new spectral measurements of the rectification groups)
	6	With TFs2 processing, based on the old–original spectral measurements as predictors (using the old–original spectral measurements for the TF calibration stage and predicting the post-ISS rectification status of the new spectral measurements of the rectification groups)
The entire old–original SSLs	7	Old–original SSLs (without ISS processing)
	8	Old–original SSLs with TFs1 processing, based on the new spectral measurements of the rectification groups
	9	Old–original SSLs with TFs2 processing, based on the old–original spectral measurements of the rectification groups