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Prepare Sentinel Imagery for Soil Moisture Prediction Using OPTRAM.

Source: R/optram.R
optram.Rd

The main wrapper function to download, and preprocess Sentinel 2 imagery then prepare the OPTRAM trapezoid to derive slope and intercept for wet and dry trapezoid lines. See: Sadeghi, M., Babaeian, E., Tuller, M., Jones, S.B., 2017. The optical trapezoid model: A novel approach to remote sensing of soil moisture applied to Sentinel-2 and Landsat-8 observations. Remote Sensing of Environment 198, 52–68, doi:10.1016/j.rse.2017.05.041

Usage

optram(
  aoi,
  from_date,
  to_date,
  S2_output_dir = tempdir(),
  data_output_dir = tempdir()
)

Arguments

aoi,

sf object, a POLYGON or MULTIPOLYGON, boundary of area of interest

from_date,

string, the start of the date range, Formatted as "YYYY-MM-DD"

to_date,

the end of the date range.

S2_output_dir,

string, directory to save downloaded S2 and the derived products, defaults to tempdir()

data_output_dir,

string, path to save coeffs_file and STR-VI data.frame, default is tempdir()

Value

rmse_df, data.frame, RMSE values of fitted trapezoid lines the coefficients are also saved to a csv file in data_output_dir.

Note

  • Sentinel downloaded products are saved to S2_output_dir. Data files (Trapezoid coefficients and STR-VI data) to data_output_dir

  • Products can be downloaded covering two "period" options: either "full" - all available images from from_date to to_date or "seasonal" - available images for all years but only for the months between day/month of from_date to the day/month of to_date. Use optram_options to set this option.

  • Three trapezoid fitting methods are implemented: "linear", "exponential" and "polynomial". See the optram_options function for details

  • Two SWIR wavelength bands are available in Sentinel-2: 1610 nanometer (nm) and 2190 nm. The option SWIR_bands can be set in optram_options to choose which band is used in this model.

  • Several vegetation indices are implemented: "NDVI", "SAVI", etc. The optram_optionsfunction also sets this option.

Examples

if (FALSE) {
from_date <- "2018-12-01"
to_date <- "2020-04-30"
aoi <- sf::st_read(system.file("extdata",
                              "lachish.gpkg", package = "rOPTRAM"))
rmse <- optram(aoi,
               from_date, to_date)
}