Mosaic rasters

Terra

library(terra)

terra 1.8.5

Directory

# dir and outdir
file_dir <- "/Users/wancher/Documents/weranch/code/tiffs/"
#setwd(file_dir)

# read in the rasters 
list_of_files <- list.files(file_dir, pattern = "S1A-.*\\.tif$", full.names = TRUE)

Commenting out the for loop and just work with files from one year for this example

# iterate over a sequence of years and pull out files specific to the year in the sequence
# mosaics <- list()
# years <- seq(2019, 2023)
# years_string <- as.character(years)
# for (i in seq_along(years_string)) {
#   
#   #pull out unique year
#   year <- years_string[[i]]
#   files_one_year <- list_of_files[grepl(year, list_of_files)]
  files_one_year <- list_of_files

  
  list_of_rasters <- lapply(files_one_year, function(file) {
    r <- rast(file)
    r
  })
  
  # get band names for retention
  #band_names <- names(list_of_rasters[[1]])
  #flattened_band_names <- unlist(band_names)
  
  # turn list in sprc and mosaic
  coll_of_rasters <- sprc(list_of_rasters)
  #print(paste0(year, " start: ", Sys.time()))
  mosaiced_raster <- merge(coll_of_rasters) 

|---------|---------|---------|---------|
=========================================
                                          

  #print(paste0(year, " finish: ", Sys.time()))
  #names(mosaiced_raster) <- band_names
  #print(names(mosaiced_raster))
  #save it
  # output_filename <- paste0(file_dir, "s1v-mosaic-", year, ".tif")
  # print(output_filename)
  # #writeRaster(mosaiced_raster, filename = output_filename, filetype = "GTiff", overwrite = TRUE)
  # mosaics[[i]] <- mosaiced_raster
  # rm(list_of_rasters, coll_of_rasters, mosaiced_raster)
  # gc()
#}

Visualize

#without mosaicing
for (r in list_of_rasters){
  plot(r)
}

#after mosaic
plot(mosaiced_raster, main = "Summer 2023 C Band Composite")