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Apply BRDF correction on S2 bands

Source: R/brdf_model.R
apply_brdf_correction.Rd

Apply BRDF correction on S2 bands

Usage

apply_brdf_correction(
  x,
  model,
  mtd_tl,
  mtd_msi,
  detector_files = NULL,
  angle_res = 60,
  shift_s2tbx = FALSE,
  sun_zenith_0 = 0.542,
  output_dir = NULL,
  overwrite = FALSE,
  write_prods = c()
)

Arguments

x

SpatRaster or list of SpatRasters named with S2 band names (e.g. B02, B03, ...).

model

Model to use for BRDF correction, see get_model().

mtd_tl

S2 MTD_TL.xml file or xml2::xml_document.

mtd_msi

S2 MTD_MSIxxx.xml file or xml2::xml_document.

detector_files

S2 detector files.

angle_res

Raster resolution of sun and viewing angles, see details.

shift_s2tbx

Logical. If TRUE, simulate the behavior of the SNAP S2 toolbox for angle interpolation.

sun_zenith_0

numeric. Mean sun zenith angle in radian at acquisition time, see details.

output_dir

character. Output directory. If NULL, nothing is written.

overwrite

logical. If TRUE, overwrite existing files.

write_prods

character. Intermediate products to write. Can be "angles", "kernels" and/or "cf". Only used if output_dir is not NULL.

Value

SpatRaster or file if output_dir is provided

Details

The algorithm is as follows:

  1. Compute sun and viewing angles

  2. Compute kernels

  3. Compute BRDF correction factor

  4. Apply BRDF correction

Parameter angle_res is used to define the raster resolution for sun and viewing angles, and kernels. Giving a low resolution will speed up the computation and save memory although there might be some border effects as the kernels are resampled at the band resolution with bilinear interpolation just before computing the BRDF correction factor.

Parameter sun_zenith_0 is the solar zenith angle in radian used to compute the BRDF correction factor. The default value is fixed to 0.542 that is the value used to compute the model included.