Sentinel 2 BRDF correction • s2brdf

Install

The installation requires git.

remotes::install_git(
  "https://gitlab.com/floriandeboissieu/sen2proc",
  ref="dev-v1")
remotes::install_git("https://forge.inrae.fr/florian.deboissieu/s2brdf")

Usage

To be able to download data Copernicus Dataspace, create an account on the plateform and add your credentials to your ~/.Rprofile or ~/.Renviron:

usethis::edit_r_profile()

and add the following

# sen2proc CDSE credentials
Sys.setenv(
  SEN2PROC_CDSE_USERNAME = "xxxxx",
  SEN2PROC_CDSE_PASSWORD = "xxxxx"
)

Download a Sentinel-2 L2A scene from Copernicus Dataspace:

download_dir <- "./data/download"
if (!dir.exists(download_dir)) {
  dir.create(download_dir, recursive = TRUE)
}

# search for a some L2A scene
stac_items <- sen2proc::s2_search(
  start = "2015-12-26",
  level = "L2A",
  tile = "32NRJ")

# download files
files <- sen2proc::cdse_download(stac_items, outdir = download_dir)
# check sen2proc documentation for authentication configuration

Compute Nadir BRDF Adjusted Reflectance:

library(s2brdf)

bands <- c("B02", "B05")
output_dir <- "./data/outputs"

if (!dir.exists(output_dir)) {
  dir.create(output_dir)
}

model <- get_brdf_model()

# get a data.frame of available scenes
s2_db <- sen2proc::s2_build_database(download_dir)

# let's process the first scene
scene <- s2_db$path[1]
scene_output_dir <- file.path(output_dir, s2_db$title[1])
if (!dir.exists(scene_output_dir)) {
  dir.create(scene_output_dir, recursive = TRUE)
}

# check all needed files are here
mtd_tl_file <- sen2proc::find_mtd_tl_file(scene)
mtd_msi_file <- sen2proc::find_mtd_msi_file(scene)
detector_files <- sen2proc::s2_detector_files(scene)
band_stack <- sen2proc::s2_band_stack(scene, bands)

# compute Nadir BRDF Adjusted Reflectance
nbar_files <- apply_brdf_correction(
  band_stack, model, mtd_tl_file, mtd_msi_file,
  output_dir = scene_output_dir,
  write_prods = c("angles", "kernels", "cf")
)

s2brdf: Sentinel-2 Nadir BRDF Adjusted Reflectance

Install

Usage