General raster read and convert

Source: R/00_warpgeneral.R

The warper is used to convert source/s to an output file or to data in memory.

gdal_raster_data(
  dsn,
  target_crs = NULL,
  target_dim = NULL,
  target_ext = NULL,
  target_res = NULL,
  resample = "near",
  bands = 1L,
  band_output_type = NULL,
  options = character()
)

gdal_raster_dsn(
  dsn,
  target_crs = NULL,
  target_dim = NULL,
  target_ext = NULL,
  target_res = NULL,
  resample = "near",
  bands = NULL,
  band_output_type = NULL,
  options = character(),
  out_dsn = tempfile(fileext = ".tif")
)

gdal_raster_image(
  dsn,
  target_crs = NULL,
  target_dim = NULL,
  target_ext = NULL,
  target_res = NULL,
  resample = "near",
  bands = NULL,
  band_output_type = NULL,
  options = character()
)

Arguments

dsn

data sources, files, urls, db strings, vrt, etc

target_crs

projection of the target grid

target_dim

dimension of the target grid

target_ext

extent of the target grid

target_res

resolution of the target grid

resample

resampling algorithm used

bands

band or bands to include, default is first band only (use NULL or a value less that one to obtain all bands)

band_output_type

specify the band type, see vapour_read_raster

options

general options passed to gdal warper

out_dsn

use with gdal_raster_dsn optionally set the output file name (or one will be generated)

Value

pixel values in a list vector per band, or a list of file paths

Details

Two functions 'gdal_raster_data' and 'gdal_raster_dsn' act like the gdalwarp command line tool, a convenience third function 'gdal_raster_image()' works especially for image data.

Examples

dsn <- system.file("extdata/sst.tif", package = "vapour")
par(mfrow = c(2, 2))
## do nothing, get native
X <- gdal_raster_data(dsn)

## set resolution (or dimension, extent, crs, or combination thereof - GDAL 
## will report/resolve incompatible opts)
X1 <- gdal_raster_data(dsn,  target_res = 1)

## add a cutline, and cut to it using gdal warp args
cutline <- system.file("extdata/cutline_sst.gpkg", package = "vapour")
X1c <- gdal_raster_data(dsn,  target_res = .1, options = c("-cutline",cutline, "-crop_to_cutline" ))
#> Error: data source could not be processed with GDALWarp api

## warp whole grid to give res
X2 <- gdal_raster_data(dsn,  target_res = 25000, target_crs = "EPSG:32755")
#> Warning: no source crs, target crs is ignored

## specify exactly (as per vapour originally)
X3 <- gdal_raster_data(dsn,  target_ext = c(-1, 1, -1, 1) * 8e6, 
 target_dim = c(512, 678), target_crs = "+proj=stere +lon_0=147 +lat_0=-90")
#> Warning: no source crs, target crs is ignored
 
X4 <- gdal_raster_dsn(dsn, out_dsn = tempfile(fileext = ".tif"))