Derivation
Calculate derivations of spectra in Speclib.
derivative.speclib(x, m = 1, method = "sgolay", ...)
x |
Object of class |
m |
Return the m-th derivative of the spectra. |
method |
Character string giving the method to be used. Valid options are |
... |
Further arguments passed to |
Two different methods are available:
Finite approximation (finApprox):
\frac{dr}{dλ}=\frac{r(λ_i)-r(λ_{i+1})}{Δλ},
where r_i is the reflection in band i and Δλ the spectral difference between adjacent bands.
Savitzky-Golay derivative computation (sgolay, default method)
Object of class Speclib.
Lukas Lehnert
Tsai, F. & Philpot, W. (1998): Derivative analysis of hyperspectral data. Remote Sensing of Environment 66/1. 41-51.
data(spectral_data) ## Calculate 1st derivation d1 <- derivative.speclib(spectral_data) ## Calculate 2nd derivation d2 <- derivative.speclib(spectral_data, m = 2) ## Calculate 3rd derivation d3 <- derivative.speclib(spectral_data, m = 3) par(mfrow=c(2,2)) plot(spectral_data) plot(d1) plot(d2) plot(d3)
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