Calculate a normalized index.
This method returns a normalized difference index value for an arbitrary pair of wavebands. There are many such indexes in use, such as NDVI (normalized difference vegetation index), NDWI (normalized difference water index), NDMI (normalized difference moisture index), etc., the only difference among then is in the wavebands used.
normalized_diff_ind(spct, plus.w.band, minus.w.band, f, ...) normalised_diff_ind(spct, plus.w.band, minus.w.band, f, ...) NDxI(spct, plus.w.band, minus.w.band, f, ...) ## Default S3 method: normalized_diff_ind(spct, plus.w.band, minus.w.band, f, ...) ## S3 method for class 'generic_spct' normalized_diff_ind(spct, plus.w.band, minus.w.band, f, ...) ## S3 method for class 'generic_mspct' normalized_diff_ind(spct, plus.w.band, minus.w.band, f, ...)
spct |
an R object |
plus.w.band |
waveband objects The waveband determine the region of the spectrum used in the calculations |
minus.w.band |
waveband objects The waveband determine the region of the spectrum used in the calculations |
f |
function used for integration taking spct as first argument and a list of wavebands as second argument. |
... |
additional arguments passed to f |
f is most frequently reflectance, but also
transmittance, or even absorbance,
response, irradiance or a user-defined function
can be used if there is a good reason for it. In every case spct
should be of the class expected by f. When using two wavebands of
different widths do consider passing to f a suitable quantity
argument. Wavebands can describe weighting functions if desired.
A named numeric value for the index, or a tibble depending on whether
a spectrum or a collection of spectra is passed as first argument. If
the wavelength range of spct does not fully overlap with both
wavebands NA is silently returned.
default: default
generic_spct:
generic_mspct:
Some NDxI indexes are directly based on satellite instrument data, such
as those in the Landsat satellites. To simulate such indexes using spectral
reflectande as input, waveband definitions provided by package
'photobiologyWavebands' can be used.
normalised_diff_ind() is a synonym for normalized_diff_ind().
NDxI() is a shorthand for normalized_diff_ind().
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