Table 1 Various multiband spectral combinations and ratios/ indices along with reference/ inference.

1.

\(\:\text{N}\text{D}\text{S}\text{S}\text{I}=\:\frac{\:\text{B}\text{l}\text{u}\text{e}-\text{N}\text{I}\text{R}}{\:\text{B}\text{l}\text{u}\text{e}+\text{N}\text{I}\text{R}}\)

³³

Polynomial Function

2.

\(\:\text{N}\text{S}\text{M}\text{I}=\:\frac{\left(\text{R}\text{e}\text{d}+\text{G}\text{r}\text{e}\text{e}\text{n}\right)-\text{B}\text{l}\text{u}\text{e}}{\text{R}\text{e}\text{d}+\text{G}\text{r}\text{e}\text{e}\text{n}+\text{B}\text{l}\text{u}\text{e}}\)

³⁴

Linear Equation

3.

\(\:\text{M}\text{o}\text{d}\text{i}\text{f}\text{i}\text{e}\text{d}\:\text{N}\text{D}\text{S}\text{S}\text{I}=\:\frac{\text{B}\text{l}\text{u}\text{e}-(\text{R}\text{e}\text{d}+\text{N}\text{I}\text{R})}{\text{B}\text{l}\text{u}\text{e}+(\text{R}\text{e}\text{d}+\text{N}\text{I}\text{R})}\)

³⁵

Polynomial Function

4.

\(\:\text{R}\text{e}\text{v}\text{i}\text{s}\text{e}\text{d}\:\text{N}\text{D}\text{S}\text{S}\text{I}\:\left(\text{R}\text{E}1\right)\:=\:\frac{\text{B}\text{l}\text{u}\text{e}-\text{R}\text{e}\text{d}\:\text{E}\text{d}\text{g}\text{e}\:1}{\text{B}\text{l}\text{u}\text{e}+\text{R}\text{e}\text{d}\:\text{E}\text{d}\text{g}\text{e}\:\:1}\)

Based on Revised NDSSI developed by 35

Polynomial Function

5.

(Red + Green) / 2

³⁶

Power Function

6.

(Red + Green + Red Edge 1) / 3

Inspired by³⁶

-

7.

Green – Red Edge 1

Through observation

-

8.

(Green × Red edge 1) / Red

Based on multiplicative approach attempted by³⁷

ANN with one hidden layer.