Merge multiple raster or spatial vector objects from disk to form a new raster or spatial vector object with a larger spatial extent. A directory with at least two raster .tif or spatial vector geopackage files should be provided. Depending on the input, the output is a .tif or a .gpkg file (saved under out_dir). If read = TRUE, the output is read into R as a SpatRaster (terra package) object in case of .tif files, or as a SpatVector (terra package) object in case of .gpkg files.
Usage
merge_tiles(
tile_dir,
tile_names,
out_dir,
file_name,
name = "stream",
compression = "low",
bigtiff = TRUE,
read = FALSE,
quiet = TRUE
)Arguments
- tile_dir
character. The directory containing the raster or spatial vectors tiles, which should be merged.
- tile_names
character. The names of the files to be merged, including the file extension (.tif or .gpkg).
- out_dir
character. The directory where the output will be stored.
- file_name
character. Name of the merged output file, including the file extension (.tif or .gpkg).
- name
character. The attribute table column name of the stream segment ("stream"), sub-catchment ("ID"), basin ("ID") or outlet ("ID") column which is used for merging GeoPackages. Default is "stream".
- compression
character. Compression of the written output file. Compression levels can be defined as "none", "low", or "high". Default is "low", referring to compression type "DEFLATE" and compression level 2. "high" refers to compression level 9.
- bigtiff
logical. Define whether the output file is expected to be a BIGTIFF (file size larger than 4 GB). If FALSE and size > 4GB no file will be written. Default is TRUE.
- read
logical. If TRUE, the merged layer gets read into R. If FALSE, the layer is only stored on disk. Default is FALSE.
- quiet
logical. If FALSE, the standard output will be printed. Default is TRUE.
Value
A .tif raster file or .gpkg spatial vector object that is always written to disk, and optionally loaded into R.
References
https://gdal.org/programs/gdalbuildvrt.html
https://gdal.org/programs/gdal_translate.html
Examples
# Download tiles into the temporary R folder
# or define a different directory
my_directory <- tempdir()
download_tiles(variable = "basin",
file_format = "tif",
tile_id = c("h22v08","h22v10"),
download_dir = my_directory)
# Define folder containing only the tiles, which should me merged
tiles_folder <- paste0(my_directory, "/r.watershed/basin_tiles20d")
# Define output folder
output_folder <- paste0(my_directory, "/merged_tiles")
# Create output folder if it doesn't exist
if(!dir.exists(output_folder)) dir.create(output_folder)
# Merge tiles
merged_tiles <- merge_tiles(tile_dir = tiles_folder,
tile_names = c("basin_h22v08.tif", "basin_h22v10.tif"),
out_dir = output_folder,
file_name = "basin_merged.tif",
read = TRUE)