write_tif: Export a data cube as a collection of GeoTIFF files

In gdalcubes: Earth Observation Data Cubes from Satellite Image Collections

Export a data cube as a collection of GeoTIFF files

Description

This function will time slices of a data cube as GeoTIFF files in a given directory.

Usage

write_tif(
  x,
  dir = tempfile(pattern = ""),
  prefix = basename(tempfile(pattern = "cube_")),
  overviews = FALSE,
  COG = FALSE,
  rsmpl_overview = "nearest",
  creation_options = NULL,
  write_json_descr = FALSE,
  pack = NULL
)

Arguments

x	a data cube proxy object (class cube)
dir	destination directory
prefix	output file name
overviews	logical; generate overview images
COG	logical; create cloud-optimized GeoTIFF files (forces overviews=TRUE)
rsmpl_overview	resampling method for overviews (image pyramid) generation (see https://gdal.org/programs/gdaladdo.html for available methods)
creation_options	additional creation options for resulting GeoTIFF files, e.g. to define compression (see https://gdal.org/drivers/raster/gtiff.html#creation-options)
write_json_descr	logical; write a JSON description of x as additional file
pack	reduce output file size by packing values (see Details), defaults to no packing

Details

If write_json_descr is TRUE, the function will write an additional file with name according to prefix (if not missing) or simply cube.json This file includes a serialized description of the input data cube, including all chained data cube operations.

Additional GDAL creation options for resulting GeoTIFF files must be passed as a named list of simple strings, where element names refer to the key. For example, creation_options = list("COMPRESS" = "DEFLATE", "ZLEVEL" = "5") would enable deflate compression at level 5.

To reduce the size of created files, values can be packed by applying a scale factor and an offset value and using a smaller integer data type for storage. The pack argument can be either NULL (the default), or a list with elements type, scale, offset, and nodata. type can be any of "uint8", "uint16" , "uint32", "int16", or "int32". scale, offset, and nodata must be numeric vectors with length one or length equal to the number of data cube bands (to use different values for different bands). The helper function pack_minmax can be used to derive offset and scale values with maximum precision from minimum and maximum data values on original scale.

If overviews=TRUE, the numbers of pixels are halved until the longer spatial dimensions counts less than 256 pixels. Setting COG=TRUE automatically sets overviews=TRUE.

Value

returns (invisibly) a vector of paths pointing to the created GeoTIFF files

See Also

pack_minmax

Examples

# create image collection from example Landsat data only 
# if not already done in other examples
if (!file.exists(file.path(tempdir(), "L8.db"))) {
  L8_files <- list.files(system.file("L8NY18", package = "gdalcubes"),
                         ".TIF", recursive = TRUE, full.names = TRUE)
  create_image_collection(L8_files, "L8_L1TP", file.path(tempdir(), "L8.db"), quiet = TRUE) 
}

L8.col = image_collection(file.path(tempdir(), "L8.db"))
v = cube_view(extent=list(left=388941.2, right=766552.4, 
              bottom=4345299, top=4744931, t0="2018-04", t1="2018-04"),
              srs="EPSG:32618", nx = 497, ny=526, dt="P1M")
write_tif(select_bands(raster_cube(L8.col, v), c("B04", "B05")), dir=tempdir())

gdalcubes documentation built on May 29, 2024, 5:11 a.m.