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, netCDF, HDF4Image, ISIS3, ISIS2, PDS4, VICAR, ERS, JP2OpenJPEG, FIT, GRIB, RMF, WMS, RST, GSAG, GSBG, GS7BG, R, KMLSUPEROVERLAY, WEBP, PDF, Rasterlite, MBTiles, CALS, WMTS, MRF, PNM, PAux, MFF, MFF2, BT, LAN, LCP, GTX, NTv2, CTable2, KRO, ROI_PAC, RRASTER, BYN, ARG, USGSDEM, BAG, NWT_GRD, ADRG, BLX, PostGISRaster, SAGA, XYZ, HF2, ZMap, SIGDEM, GPKG, NGW, ENVI, EHdr, ISCE, Zarr

options=string[,string,...]

Creation options

Storing results from raster data analysis directly as GeoTIFF¶

The module r.external.out is used to write out processing results directly 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