#' frg_modproc
#'@description Function used to download, mosaic and preprocess MODIS data
#'@details Function used to download, mosaic and preprocess MODIS data.
#'1. **Download and Mosaicing**:
#' Images covering Europe for end July - mid august of each selected
#' year are downloaded, mosaiced and reprojected
#' Resulting images are saved in TIFF format in the Originals subfolder
#' of the output folder selected by the user. Separate subfolders are used
#' to store images related to NDVI, RED and NIR reflectance, QA
#' (Quality Assurance) and Pixel Reliability.
#'2. **Preprocessing**:
#' The preprocessing steps conducted are the following:
#' a. MODIS UI (Usefulness Index) values are extracted from the MODIS QA
#' (Quality Assurance) files
#' c. The average yearly values for DVI and NDVI are computed starting from the
#' images of DOY 209 and 225. NODATA and bad quality data#' are automatically removed
#'
#' @param opts string Folder where the original and preprocessed image will be stored
#' @param UI_check flag If = 1 then a chack on pixel usefulness index is done while
#' determining pixels to be used to compute average NDVI. default = 1
#' @param max_UI Max UI value kept when averaging MODIS data. default = 5
#' @param force_update DESCRIPTION , Default: FALSE
#'
#' @author Lorenzo Busetto (2016)
#' email: lbusett@gmail.com
#'
#' @export
#'
frg_process_modis <- function(opts,
UI_check,
max_UI,
force_update) {
# Create output folder and Initialize processing variables ----
# Print Messages ----
message("-------------------------------------------")
message("---- MODIS Download and PreProcessing -----")
message("-------------------------------------------")
message("----> Main MODIS Folder: ", opts$out_origpath)
message("-------------------------------------------")
message("---- Downloading, and Preprocessing of MODIS data ---> RUNNING <--- ")
# Download MODIS images using MODIStsp for each selected year ------
# options file is saved in inst/Ext/frg_modistsp_opts.json
for (yy in seq(opts$start_year, opts$end_year, 1)) {
er <- frg_download_modis(opts, yy)
# Compute yearly average values from 209 and 225 images ----
message("---- Computing Average of summer values for ", yy, "-----")
er <- frg_compmean(opts,
yy,
UI_check,
max_UI,
force_update)
} # End Cycle on years
message("---- Downloading, and Preprocessing of MODIS data ---> COMPLETED <--- ")
return("DONE") # Return processing variables
}
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