Extract averaged spectrum from hyperspectral raster

Aggregate a hyperspectral raster to a single spectrum representing the mean (or other summary) across all pixels. Useful for examining representative spectral signatures of regions of interest.

Usage

hsi_extract_spectrum(x, fun = "mean")

Arguments

x

A SpatRaster with hyperspectral data. Band names must be numeric wavelengths in nm.

fun

Character. Aggregation function passed to terra::aggregate(). Default "mean". Other terra summary functions are also supported.

Value

A tibble with columns:

wavelength

Numeric. Wavelength in nm.

value

Numeric. Aggregated reflectance value.

Details

Returns one value per wavelength band. To extract a spectrum from a specific region, crop the raster first with terra::crop().

See also

hsi_extract_profile() for extracting values along a spatial axis.

Other HSI Extraction: hsi_extract_profile()

Examples

if (FALSE) { # \dontrun{
x <- terra::rast("REFLECTANCE_testdata.tif")

spectrum <- hsi_extract_spectrum(x)

spectrum_roi <- x |>
  terra::crop(my_extent) |>
  hsi_extract_spectrum()

spectrum_median <- hsi_extract_spectrum(x, fun = "median")
} # }