Derive red edge parameters from hyperspectral data
List of class
Logical indicating if spectral data should be smoothed. See details section.
Logical indicating if resulting wavelength position should be rounded.
Further arguments passed to
Shape and location of the red edge are commonly described by four parameters:
R0: minimum reflectance in the red spectrum
l0: wavelength of the minimum reflectance
lp: inflection point
Rs: shoulder wavelength
The red edge parameters are calculated as proposed in Bach (1995) from the spectral area between 550 and 900 nm. l0 is calculated as the last root before the maximum value of the 2nd derivation. The minimum reflectance is the reflectance at (l0). The inflection point is the root of the 2nd derivative function between the maximum value and the minimum value. The shoulder wavelength is the first root beyond the minimum value of the 2nd derivation.
Optional smoothing is performed with
smoothSpeclib(x, method = "spline", n = round(nbands(x)/10,0))
prior to all calculations. Note that reflectance values returned by the
rededge-function are original values and not the smoothed reflectances. This would not be the case, if already smoothed reflectance values are passed to
A data frame containing parameters for each spectrum.
Bach, H. (1995): Die Bestimmung hydrologischer und landwirtschaftlicher Oberflaechenparameter aus hyperspektralen Fernerkundungsdaten. Muenchner Geographische Abhandlungen Reihe B, Band B21.
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