Table 3 Overview of RGB-based vegetation indices derived from UAV images in this study (r, g, and b are related to the scaling and normalized values)

E1

Excess Green (EXG)

\(2g-r-b\)

[36]

E2

Excess Red (EXR)

\(1.4r-g\)

[37]

E3

Excess Blue (EXB)

\(1.4b-g\)

[38]

E4

Excess green minus excess red (EXGR)

\(EXG-EXR\)

[39]

E5

Green blue difference (GBDI)

\(g-b\)

[40]

E6

Color index of vegetation extraction (CIVE)

\(0.441r-0.811g+0.385b+18.78745\)

[41]

E7

Green-red ratio index (GRRI)

g/r

[42]

E8

Normalized green red difference index (NGRDI)

\((g-r)/(g+r)\)

[43]

E9

Normalized green blue difference index (NGBDI)

\((g-b)/(g+b)\)

[44]

E10

Modified green red Vegetation Index (MGRVI)

\((g^2-r^2)/(g^2+r^2)\)

[45]

E11

Visible-band difference vegetation index (VDVI)

\((2g-r-b)/(2g+r+b)\)

[46]

E12

Vegetative index (VEG)

\(g/r^\alpha b^(1-\alpha )\)

[33]

E13

Combination of green (COM)

\(0.36EXG+0.47CIVE+0.17VEG\)

[47]

E14

Visible atmospherically resistant index (VARI)

\((g-r)/(g+r-b)\)

[34]

E15

Kawashima index (IKAW)

\((r-b)/(r+b)\)

[48]

E16

RGB Vegetation Index (RGBVI)

\((g^2-b\times r)/(b^2+b\times r)\)

[45]