NAME

       r.external.out   -  Redirects  raster  output  to  file utilizing GDAL library 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,  NITF, HFA, ELAS, AAIGrid, DTED, PNG, JPEG, MEM, GIF, XPM, BMP,
           PCIDSK, PCRaster, ILWIS, SGI, SRTMHGT, Leveller,  Terragen,  GMT,  netCDF,  HDF4Image,
           ISIS3,  ISIS2,  ERS,  JP2OpenJPEG,  FIT,  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, ENVI, EHdr, ISCE, ARG,
           USGSDEM, NWT_GRD, ADRG, BLX, EPSILON, PostGISRaster, SAGA, XYZ, HF2, ZMap, GPKG

       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 occur 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  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 $HOME/gisoutput/
       r.external.out directory=$HOME/gisoutput/ format="GTiff"
       # 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

       Last changed: $Date: 2017-02-28 17:48:37 +0100 (Tue, 28 Feb 2017) $

SOURCE CODE

       Available at: r.external.out source code (history)

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       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual