.TH r.external.out 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBr.external.out\fR\fR  \- Redirects raster output to file utilizing GDAL library rather than storing in GRASS raster format.
.SH KEYWORDS
raster, export, output, external
.SH SYNOPSIS
\fBr.external.out\fR
.br
\fBr.external.out \-\-help\fR
.br
\fBr.external.out\fR [\-\fBfrp\fR] \fBdirectory\fR=\fIpath\fR  [\fBextension\fR=\fIstring\fR]  \fBformat\fR=\fIstring\fR  [\fBoptions\fR=\fIstring\fR[,\fIstring\fR,...]]   [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-f\fR" 4m
.br
List supported formats and exit
.IP "\fB\-r\fR" 4m
.br
Cease using GDAL and revert to native output
.IP "\fB\-p\fR" 4m
.br
Print current status
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBdirectory\fR=\fIpath\fR \fB[required]\fR" 4m
.br
Name of output directory
.IP "\fBextension\fR=\fIstring\fR" 4m
.br
Extension for output files
.IP "\fBformat\fR=\fIstring\fR \fB[required]\fR" 4m
.br
Format of output files
.br
Options: \fIVRT, 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, EPSILON, PostGISRaster, SAGA, XYZ, HF2, JPEGLS, ZMap, SIGDEM, GPKG, NGW, ENVI, EHdr, ISCE\fR
.IP "\fBoptions\fR=\fIstring[,\fIstring\fR,...]\fR" 4m
.br
Creation options
.SH DESCRIPTION
\fIr.external.out\fR 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.
.PP
Any new raster map is immediately written out through GDAL as a file.
.SH NOTES
A relative directory path (parameter \fIdirectory\fR) 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 \fIoutput\fR) results
in the output file being placed in the \(dqgdal/\(dq subdirectory of the
current mapset directory.
.SH EXAMPLES
.SS Storing results from raster data analysis directly as GeoTIFF
The module \fIr.external.out\fR is used to write out processing results
directly in GeoTIFF format (any GDAL supported format can be used here):
.br
.nf
\fC
# 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=\(dqGTiff\(dq option=\(dqBIGTIFF=YES,COMPRESS=DEFLATE\(dq
# 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 \(dqelev_filt.tif = if(elevation > 120.0, elevation, null() )\(dq
# ...the \(dqelev_filt.tif\(dq is immediately written.
# cease GDAL output connection and turn back to write out GRASS raster files:
r.external.out \-r
# verify resulting file
gdalinfo $HOME/gisoutput/elev_filt.tif
\fR
.fi
.SS Complete workflow using only external geodata while processing in GRASS GIS
The module \fIr.external.out\fR can be used along with
\fIr.external\fR to process external geodata in GRASS
while writing out the results directly in GeoTIFF:
.br
.nf
\fC
# register GeoTIFF file to be used in current mapset:
r.external input=terra_lst1km20030314.LST_Day.tif output=modis_celsius
# define output directory for files resulting from GRASS calculation:
r.external.out directory=$HOME/gisoutput/ format=\(dqGTiff\(dq
# perform GRASS calculation (here: extract pixels > 20 deg C)
# this stores the output map directly as GeoTIFF:
r.mapcalc \(dqwarm.tif = if(modis_celsius > 20.0, modis_celsius, null() )\(dq
# 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
\fR
.fi
.SH REFERENCES
GDAL Pages: http://www.gdal.org/
.br
.SH SEE ALSO
\fI
r.in.gdal,
r.out.gdal,
r.external
\fR
.SH AUTHOR
Glynn Clements
.SH SOURCE CODE
.PP
Available at: r.external.out source code (history)
.PP
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.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual