Skip to contents

Create and save a multi-band output raster by combining input rasters

Source: R/stack_rasters.R
stack_rasters.Rd

This function creates an output raster that "stacks" all the bands of its input rasters, as though they were loaded one after another into a GIS. It does this by first constructing a GDAL virtual raster, or "VRT", and then optionally uses GDAL's warper to convert this VRT into a standalone file. The VRT is fast to create and does not require much space, but does require the input rasters not be moved or altered. Creating a standalone raster from this file may take a long time and a large amount of disk space.

Usage

stack_rasters(
  rasters,
  output_filename,
  ...,
  resolution,
  extent,
  reference_raster = 1,
  resampling_method = "bilinear",
  band_names,
  check_crs = TRUE,
  gdalwarp_options = c("-multi", "-overwrite", "-co", "COMPRESS=DEFLATE", "-co",
    "PREDICTOR=2", "-co", "NUM_THREADS=ALL_CPUS"),
  gdal_config_options = c(VSI_CACHE = "TRUE", GDAL_CACHEMAX = "30%", VSI_CACHE_SIZE =
    "10000000", GDAL_HTTP_MULTIPLEX = "YES", GDAL_INGESTED_BYTES_AT_OPEN = "32000",
    GDAL_DISABLE_READDIR_ON_OPEN = "EMPTY_DIR", GDAL_HTTP_VERSION = "2",
    GDAL_HTTP_MERGE_CONSECUTIVE_RANGES = "YES", GDAL_NUM_THREADS = "ALL_CPUS")
)

Arguments

rasters

A list of rasters to combine into a single multi-band raster, as character file paths to files that can be read by terra::rast(). Rasters will be "stacked" upon one another, preserving values. They must share CRS.

output_filename

The location to save the final "stacked" raster. If this filename has a "vrt" extension as determined by tools::file_ext(), then this function exits after creating a VRT; otherwise, this function will create a VRT and then use sf::gdal_utils("warp") to convert the VRT into another format.

...

These dots are for future extensions and must be empty.

resolution

Numeric of length 2, representing the target X and Y resolution of the output raster. If only a single value is provided, it will be used for both X and Y resolution; if more than 2 values are provided, an error is thrown.

extent

Numeric of length 4, representing the target xmin, ymin, xmax, and ymax values of the output raster (its bounding box), in that order.

reference_raster

The position (index) of the raster in rasters to take extent, resolution, and CRS information from. No reprojection is done. If resolution or extent are provided, they override the values from the reference raster.

resampling_method

The method to use when resampling to different resolutions in the VRT.

band_names

Either a character vector of band names, or a function that when given a character vector of band names, returns a character vector of the same length containing new band names.

check_crs

Logical: Should this function check that all rasters share the same CRS? Set to FALSE only if you are entirely confident that rasters have equivalent CRS definitions, but not identical WKT strings.

gdalwarp_options

Options passed to gdalwarp through the options argument of sf::gdal_utils(). This argument is ignored (with a warning) if output_filename is a VRT.

gdal_config_options

Options passed to gdalwarp through the config_options argument of sf::gdal_utils(). This argument is ignored (with a warning) if output_filename is a VRT.

Value

output_filename, unchanged.

Examples

stack_rasters(
  list(
    system.file("rasters/dpdd.tif", package = "rsi"),
    system.file("rasters/example_sentinel1.tif", package = "rsi")
  ),
  tempfile(fileext = ".vrt")
)
#> [1] "/tmp/RtmpopigZF/file1a4257cc4aa.vrt"