derivative_speclib: Derivation

Description Usage Arguments Details Value Author(s) References See Also Examples

Description

Calculate derivations of spectra

Usage

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derivative.speclib(x, m = 1, method = "sgolay", ...)

Arguments

x

Object of class Speclib.

m

Return the m-th derivative of the spectra.

method

Character string giving the method to be used. Valid options are "finApprox" or "sgolay".

...

Further arguments passed to sgolayfilt.

Details

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)

Value

Object of class Speclib.

Author(s)

Lukas Lehnert

References

Tsai, F. & Philpot, W. (1998): Derivative analysis of hyperspectral data. Remote Sensing of Environment 66/1. 41-51.

See Also

sgolayfilt, vegindex

Examples

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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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