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Convolve reflectance onto a sensor using a plain per-band SRF table

get.spectral.convolution.srf.Rd

get.spectral.convolution.rfl() needs a sensor object with SMAC atmospheric-correction coefficients bundled (see its own docs for the 9 supported sensors) – fine for Landsat/OLCI/MODIS, but PRISMA has no SMAC coefficients at all, and Sentinel-2A/B additionally ship a second, plain, publisher-original spectral response function table alongside their SMAC bundle. This function convolves onto any of those "just a per-band SRF table, nothing else" sensors instead – one shared implementation for ToolsRTM::srf.prisma, ToolsRTM::srf.sentinel2a, and ToolsRTM::srf.sentinel2b (generalizes what used to be two separate, app-only helper functions, convolve_prisma()/convolve_smac_sensor(), in the AEO-Course PROSAIL Shiny app's own app.R).

Usage

get.spectral.convolution.srf(df, srf, fwhm = NULL, get.plots = FALSE)

Arguments

df

A data frame with a wave column (wavelength, nm) and an rfl column (reflectance) – same convention as get.spectral.convolution.rfl().

srf

A plain per-band SRF table: its FIRST column is wavelength (nm, any column name), every other column is one sensor band's SRF weight at that wavelength (e.g. ToolsRTM::srf.prisma, ToolsRTM::srf.sentinel2a, ToolsRTM::srf.sentinel2b).

fwhm

Optional data frame with a fwhm column, one row per band in srf (same order), e.g. ToolsRTM::fwhm.prisma – when supplied, its (precisely interpolated) FWHM values are used instead of the coarser half-max-crossing estimate this function would otherwise derive directly from srf's own sampled weight profile. Sentinel-2A/B have no equivalent bundled FWHM table, so leave this NULL for them.

get.plots

logical, plot the convolved spectrum? Default FALSE.

Value

A data frame with one row per SRF column: band (index), wl (SRF-weighted mean center wavelength, nm), fwhm (full width at half maximum, nm), RFL (convolved reflectance).

Examples

df <- data.frame(wave = ToolsRTM::dataSpec_PDB[, 1],
                  rfl = 0.05 + 0.3 * ToolsRTM::dataSpec_PDB[, 1] / 2500)
prisma_bands <- get.spectral.convolution.srf(df, ToolsRTM::srf.prisma,
                                              fwhm = ToolsRTM::fwhm.prisma)
s2a_bands <- get.spectral.convolution.srf(df, ToolsRTM::srf.sentinel2a)