Table 4 Performance of soil free iron content models based on principal component analysis (PCA) spectrum.

From: Estimation of soil free Iron content using spectral reflectance and machine learning algorithms

Spectral

Modeling

Training

Testing

Transform

Methods

R2

RMSE (g/kg)

RRMSE (%)

R2

RMSE (g/kg)

RRMSE (%)

Original

PLS

0.641

7.02

31.2

0.609

7.041

32.6

SVM

0.705

6.633

31.4

0.645

6.881

31.4

RF

0.953

3.244

14.7

0.736

6.334

28.9

DNN

0.805

5.453

24.6

0.751

5.902

26.9

FD

PLS

0.847

4.579

20.6

0.76

5.539

25.7

SVM

0.876

4.085

18.8

0.803

5.231

23.8

RF

0.99

4.497

20.3

0.460

10.325

47.0

DNN

0.900

4.597

19.4

0.807

5.875

26.8

SNV

PLS

0.642

7.019

31.4

0.625

6.967

32.3

SVM

0.713

6.408

30.3

0.623

7.264

33.1

RF

0.950

3.396

15.4

0.639

7.204

32.8

DNN

0.812

5.203

23.7

0.752

5.955

27.1

CR

PLS

0.790

7.019

31.4

0.732

6.967

32.3

SVM

0.726

6.408

30.3

0.715

7.264

33.1

RF

0.960

3.396

15.4

0.703

7.204

32.8

DNN

0.826

5.203

23.7

0.715

5.955

27.1