r.external.out(1grass) GRASS GIS User's Manual r.external.out(1grass)
NAME
r.external.out - Redirects raster output to file utilizing GDAL li-
brary rather than storing in GRASS raster format.
KEYWORDS
raster, export, output, external
SYNOPSIS
r.external.out
r.external.out --help
r.external.out [-frp] directory=path [extension=string] format=string
[options=string[,string,...]] [--help] [--verbose] [--quiet]
[--ui]
Flags:
-f
List supported formats and exit
-r
Cease using GDAL and revert to native output
-p
Print current status
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
directory=path [required]
Name of output directory
extension=string
Extension for output files
format=string [required]
Format of output files
Options: VRT, GTiff, COG, NITF, HFA, ELAS, AAIGrid, DTED, PNG,
JPEG, MEM, GIF, FITS, XPM, BMP, PCIDSK, PCRaster, ILWIS, SGI,
SRTMHGT, Leveller, Terragen, GMT, netCDF, HDF4Image, ISIS3, ISIS2,
PDS4, VICAR, ERS, JP2OpenJPEG, FIT, GRIB, RMF, WMS, RST, INGR,
GSAG, GSBG, GS7BG, R, KMLSUPEROVERLAY, WEBP, PDF, Rasterlite,
MBTiles, CALS, WMTS, MRF, PNM, PAux, MFF, MFF2, BT, LAN, IDA, LCP,
GTX, NTv2, CTable2, KRO, ROI_PAC, RRASTER, BYN, ARG, USGSDEM, BAG,
NWT_GRD, ADRG, BLX, PostGISRaster, SAGA, XYZ, HF2, JPEGLS, ZMap,
SIGDEM, GPKG, NGW, ENVI, EHdr, ISCE, Zarr
options=string[,string,...]
Creation options
DESCRIPTION
r.external.out instructs GRASS GIS to write subsequently generated
raster maps as data files (e.g. GeoTIFF) using GDAL instead of storing
them in GRASS raster format in the current mapset.
Any new raster map is immediately written out through GDAL as a file.
NOTES
A relative directory path (parameter directory) is interpreted relative
to the current mapset directory, not the current directory where the
command was launched. An unspecified or empty directory (which will oc-
cur if the user passes a simple filename for output) results in the
output file being placed in the "gdal/" subdirectory of the current
mapset directory.
EXAMPLES
Storing results from raster data analysis directly as GeoTIFF
The module r.external.out is used to write out processing results di-
rectly in GeoTIFF format (any GDAL supported format can be used here):
# define output directory for files resulting from GRASS calculation(s)
# and target format:
mkdir $HOME/gisoutput/
# hint: the create options are not mandatory
r.external.out directory=$HOME/gisoutput/ format="GTiff" option="BIGTIFF=YES,COMPRESS=DEFLATE"
# prepare sample analysis
g.region raster=elevation -p
# perform GRASS calculation (here: filter by height, write > 120m, NULL otherwise)
# this will store the output map directly as GeoTIFF, so we use .tif extension:
r.mapcalc "elev_filt.tif = if(elevation > 120.0, elevation, null() )"
# ...the "elev_filt.tif" is immediately written.
# cease GDAL output connection and turn back to write out GRASS raster files:
r.external.out -r
# verify resulting file
gdalinfo $HOME/gisoutput/elev_filt.tif
Complete workflow using only external geodata while processing in GRASS GIS
The module r.external.out can be used along with r.external to process
external geodata in GRASS while writing out the results directly in
GeoTIFF:
# register GeoTIFF file to be used in current mapset:
r.external input=terra_lst1km20030314.LST_Day.tif output=modis_celsius
# define output directory for files resulting from GRASS calculation:
r.external.out directory=$HOME/gisoutput/ format="GTiff"
# perform GRASS calculation (here: extract pixels > 20 deg C)
# this stores the output map directly as GeoTIFF:
r.mapcalc "warm.tif = if(modis_celsius > 20.0, modis_celsius, null() )"
# cease GDAL output connection and turn back to write GRASS raster files:
r.external.out -r
# now use the resulting file elsewhere
gdalinfo $HOME/gisoutput/warm.tif
REFERENCES
GDAL Pages: http://www.gdal.org/
SEE ALSO
r.in.gdal, r.out.gdal, r.external
AUTHOR
Glynn Clements
SOURCE CODE
Available at: r.external.out source code (history)
Accessed: unknown
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© 2003-2022 GRASS Development Team, GRASS GIS 7.8.7 Reference Manual
GRASS 7.8.7 r.external.out(1grass)
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