gdalcubes (version 0.5.1)

create_image_collection: Create an image collection from a set of GDAL datasets or files

Description

This function iterates over files or GDAL dataset identifiers and extracts datetime, image identifiers, and band information according to a given collection format.

Usage

create_image_collection(
  files,
  format = NULL,
  out_file = tempfile(fileext = ".sqlite"),
  date_time = NULL,
  band_names = NULL,
  use_subdatasets = FALSE,
  unroll_archives = TRUE,
  quiet = FALSE
)

Arguments

files

character vector with paths to image files on disk or any GDAL dataset identifiers (including virtual file systems and higher level drivers or GDAL subdatasets)

format

collection format, can be either a name to use predefined formats (as output from collection_formats) or a path to a custom JSON format description file

out_file

optional name of the output SQLite database file, defaults to a temporary file

date_time

vector with date/ time for files; can be of class character, Date, or POSIXct (argument is only applicable for image collections without collection format)

band_names

character vector with band names, length must match the number of bands in provided files (argument is only applicable for image collections without collection format)

use_subdatasets

logical; use GDAL subdatasets of provided files (argument is only applicable for image collections without collection format)

unroll_archives

automatically convert .zip, .tar archives and .gz compressed files to GDAL virtual file system dataset identifiers (e.g. by prepending /vsizip/) and add contained files to the list of considered files

quiet

logical; if TRUE, do not print resulting image collection if return value is not assigned to a variable

Value

image collection proxy object, which can be used to create a data cube using raster_cube

Details

An image collection is a simple SQLite database file that indexes and references existing image files / GDAL dataset identifiers.

Collections can be created in two different ways: First, if a collection format is specified (argument format), date/time, bands, and metadata are automatically extracted from provided files / GDAL datasets. Second, image collections can be created without collection format by manually specifying date/time of images (argument date_time) and (optional) names of bands. In this case, however, all provided images must contain the same bands. If this is not possible for a dataset, a collection format must be used.

Examples

# NOT RUN {
# 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")) 
}
# }