ndvi2: Calculate and plot a 2-band NDVI.
In visa: Vegetation Imaging Spectroscopy Analyzer

This function calculates a 2-band NDVI using the nsr function.

1	ndvi2(s, b1, b2)

`s`	Spectral data in the format of visa's Spectra object, spectra.data.frame or spectra.matrix.
`b1`	A integer number which defines the wavelength of the 1st spectral band.
`b2`	A integer number which defines the wavelength of the 2nd spectral band.

Calculate a NDVI with two specific bands of choice. The new NDVI follows the the standard formula

NDVI = (λ_i + λ_j)/(λ_i - λ_j)

. Bands i and j correspond to the b1 and b2 input arguments, respectively. Wavelength indexes are determined based on the first argument 's'.

ndvi

The returned values are the new NDVI.

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library(visa)
s <- NSpec.DF$spectra
ndvi2(s, 780, 680)

visa documentation built on April 20, 2021, 9:07 a.m.

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