Get Convolved Spectra — get.spectra.convolved • ToolsRTM

This function performs spectral convolution using specified sensor spectral response functions (SRFs). It can interpolate the input spectra to match the SRF resolution and plot the convolved and observed spectra.

Usage

get.spectra.convolved(rfl, sensor, plot.spectra = T)

Arguments

rfl: A matrix or data frame of reflectance spectra, with columns representing wavelengths.
sensor: A character string specifying the sensor to use for convolution. Options are "sentinel2a", "sentinel2b", or "prisma". If NULL, "sentinel2a" is used by default.
plot.spectra: A logical value indicating whether to plot the convolved and observed spectra. Default is TRUE.

Value

A data frame of convolved spectra.

Examples

if (FALSE) { # \dontrun{
#spectral response function downloaded from:
#https://oceancolor.gsfc.nasa.gov/resources/docs/rsr_tables/

# 1. Generate a Lookup Table (LUT) for PROSAIL inputs

inputs.prosail <- ToolsRTM::inputsPROSAIL
# Create a LUT with 1 entry using the defined PROSAIL inputs
df.LUT <- as.data.frame(ToolsRTM::getLUT(inputs = inputs.prosail, nLUT = 1, setseed = 1234))

# 2. Simulate spectral reflectance using PROSAIL and apply BRDF effect

# Simulate reflectance values using the PROSAIL model for the first LUT entry
reflectance_values <- ToolsRTM::foursail(inputLUT = df.LUT[1,], rsoil = rsoil,
                                          LeafModel = 'PROSPECT-PRO')
rdot <- reflectance_values[[1]]  # Direct reflectance
rsot <- reflectance_values[[2]]  # Diffuse reflectance

# Compute the Bidirectional Reflectance Factor (BRF) using BRDF effects
reflectance_values <- ToolsRTM::Compute_BRF(rdot = rdot, rsot = rsot,
                                            tts = df.LUT[1, 'tts'],
                                            data.light = ToolsRTM::dataSpec_PDB)
# Convert the reflectance values to a matrix for further processing
sim.matrix <- as.matrix(t(reflectance_values))
colnames(sim.matrix)=paste0("X",wavelength)
# 3. Convolve the simulated reflectance with a sensor-specific SRF and plot the result

# Here, we use the Sentinel-2A sensor for spectral resampling and plotting
convolved_spectra <- get.spectra.convolved(rfl = sim.matrix, sensor = "Sentinel2a",
                                            plot.spectra = TRUE)
} # }