continuumRemoval {prospectr} | R Documentation |
Compute the continuum removed values of a data
matrix
, data.frame
, or vector
as
implemented in ENVI
continuumRemoval(X,wav,type,interpol,method)
X |
numeric |
wav |
optional. numeric |
type |
type of data: 'R' for reflectance (default), 'A' for absorbance |
interpol |
interpolation method between points on the convex hull: 'linear' (default) or 'spline' |
method |
normalization method: 'division' (default) or 'substraction' (see details section) |
The continuum removal technique was introduced by Clark and Roush (1984) as a method to highlight energy absorption features of minerals. It can be viewed as a way to perform albedo normalization. The algorithm find points lying on the convex hull (local maxima or envelope) of a spectrum, connects the points by linear or spline interpolation and normalizes the spectrum by dividing (or substracting) the input data by the interpolated line.
a matrix
or vector
with the filtered
signal(s)
Antoine Stevens
Clark, R.N., and Roush, T.L., 1984. Reflectance Spectroscopy: Quantitative Analysis Techniques for Remote Sensing Applications. J. Geophys. Res. 89, 6329-6340.
sgolayfilt
,
savitzkyGolay
, movav
,
gapDer
, binning
data(NIRsoil) wav <- as.numeric(colnames(NIRsoil$spc)) # plot of the 10 first abs spectra matplot(wav,t(NIRsoil$spc[1:10,]),type='l',ylim=c(0,.6),xlab='Wavelength /nm',ylab='Abs') # type = 'A' is used for absorbance spectra cr <- continuumRemoval(NIRsoil$spc,wav,type='A') matlines(wav,t(cr[1:10,]))