vapour_create: Create raster file

In hypertidy/vapour: Access to the 'Geospatial Data Abstraction Library' ('GDAL')

Create raster file

Description

This is in an incomplete interface to raster writing, for exploring.

Usage

vapour_create_options(driver = "GTiff")

vapour_create(
  filename,
  driver = "GTiff",
  extent = c(-180, 180, -90, 90),
  dimension = c(2048, 1024),
  projection = "OGC:CRS84",
  n_bands = 1L,
  overwrite = FALSE,
  datatype = "Float32",
  options = vapour_create_options(driver)
)

Arguments

driver	GDAL driver to use (GTiff is default, and recommended)
filename	filename/path to create
extent	xmin,xmax,ymin,ymax 4-element vector
dimension	dimension of the output, X * Y
projection	projection of the output, best to use a full WKT but any string accepted
n_bands	number of bands in the output, default is 1
overwrite	not TRUE by default
datatype	the name of a GDAL datatype ('Float32', 'Int64', etc)
options	character vector of creation of options for the driver in use c('COMPRESS=DEFLATE') note how these are constructed (no '-co' element)

Details

If GeoTIFF is used (driver = "GTiff", recommended) then the output is tiled 512x512, and has DEFLATE compression, and is sparse when created (no values are initiated, so the file is tiny).

Note that there is no restriction on where you can read or write from, the responsibility is yours. There is no auto driver detection done for the file format, it's up to you to set the file extension and the driver.

File is created using CreateCopy from a VRT in memory. This is so that we can instantiate COG layer with 'driver = "COG"'. Please note that performance is best for GTiff itself, with 'SPARSE_OK=YES'. We don't yet know how to instantiate a large COG with overviews.

There are default creation options set for COG and GTiff drivers, see 'vapour_create_options(driver "GTiff")' for what those are.

Value

the file path that was created

Examples

tfile <- tempfile(fileext = ".tif")
if (!file.exists(tfile)) {
 vapour_create(tfile, extent = c(-1, 1, -1, 1) * 1e6, 
                     dimension = c(128, 128), 
                     projection = "+proj=laea")
 file.remove(tfile)
}

hypertidy/vapour documentation built on March 2, 2024, 7:59 p.m.