r.external.out(1grass)

1r.external.out(1)           GRASS GIS User's Manual          r.external.out(1)
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NAME

6       r.external.out   -  Redirects  raster output to file utilizing GDAL li‐
7       brary rather than storing in GRASS raster format.
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KEYWORDS

10       raster, export, output, external
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SYNOPSIS

13       r.external.out
14       r.external.out --help
15       r.external.out [-frp] directory=path  [extension=string]  format=string
16       [options=string[,string,...]]      [--help]    [--verbose]    [--quiet]
17       [--ui]
18
19   Flags:
20       -f
21           List supported formats and exit
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23       -r
24           Cease using GDAL and revert to native output
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26       -p
27           Print current status
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29       --help
30           Print usage summary
31
32       --verbose
33           Verbose module output
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35       --quiet
36           Quiet module output
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38       --ui
39           Force launching GUI dialog
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41   Parameters:
42       directory=pathÂ [required]
43           Name of output directory
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45       extension=string
46           Extension for output files
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48       format=stringÂ [required]
49           Format of output files
50           Options: VRT, GTiff, COG, NITF, HFA, ELAS, AAIGrid, DTED, PNG, GTA,
51           JPEG,  MEM,  GIF,  FITS,  XPM,  BMP,  PCIDSK, PCRaster, ILWIS, SGI,
52           SRTMHGT, Leveller, Terragen, GMT, netCDF, HDF4Image, ISIS3,  ISIS2,
53           PDS4,  VICAR, ERS, JP2OpenJPEG, FIT, GRIB, JPEG2000, RMF, WMS, RST,
54           INGR, GSAG, GSBG, GS7BG, R, KMLSUPEROVERLAY, WEBP, PDF, Rasterlite,
55           MBTiles,  CALS, WMTS, MRF, PNM, PAux, MFF, MFF2, BT, LAN, IDA, LCP,
56           GTX, NTv2, CTable2, KRO, ROI_PAC, RRASTER, BYN, ARG, USGSDEM,  BAG,
57           NWT_GRD,  ADRG,  BLX,  PostGISRaster, SAGA, XYZ, HF2, ZMap, SIGDEM,
58           GPKG, NGW, ENVI, EHdr, ISCE, Zarr
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60       options=string[,string,...]
61           Creation options
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DESCRIPTION

64       r.external.out instructs GRASS  GIS  to  write  subsequently  generated
65       raster  maps as data files (e.g. GeoTIFF) using GDAL instead of storing
66       them in GRASS raster format in the current mapset.
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68       Any new raster map is immediately written out through GDAL as a file.
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NOTES

71       A relative directory path (parameter directory) is interpreted relative
72       to  the  current  mapset directory, not the current directory where the
73       command was launched. An unspecified or empty directory (which will oc‐
74       cur  if  the  user  passes a simple filename for output) results in the
75       output file being placed in the "gdal/"  subdirectory  of  the  current
76       mapset directory.
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EXAMPLES

79   Storing results from raster data analysis directly as GeoTIFF
80       The  module  r.external.out is used to write out processing results di‐
81       rectly in GeoTIFF format (any GDAL supported format can be used here):
82       # define output directory for files resulting from GRASS calculation(s)
83       # and target format:
84       mkdir $HOME/gisoutput/
85       # hint: the create options are not mandatory
86       r.external.out directory=$HOME/gisoutput/ format="GTiff" option="BIGTIFF=YES,COMPRESS=DEFLATE"
87       # prepare sample analysis
88       g.region raster=elevation -p
89       # perform GRASS calculation (here: filter by height, write > 120m, NULL otherwise)
90       # this will store the output map directly as GeoTIFF, so we use .tif extension:
91       r.mapcalc "elev_filt.tif = if(elevation > 120.0, elevation, null() )"
92       # ...the "elev_filt.tif" is immediately written.
93       # cease GDAL output connection and turn back to write out GRASS raster files:
94       r.external.out -r
95       # verify resulting file
96       gdalinfo $HOME/gisoutput/elev_filt.tif
97
98   Complete workflow using only external geodata while processing in GRASS GIS
99       The module r.external.out can be used along with r.external to  process
100       external  geodata  in  GRASS  while writing out the results directly in
101       GeoTIFF:
102       # register GeoTIFF file to be used in current mapset:
103       r.external input=terra_lst1km20030314.LST_Day.tif output=modis_celsius
104       # define output directory for files resulting from GRASS calculation:
105       r.external.out directory=$HOME/gisoutput/ format="GTiff"
106       # perform GRASS calculation (here: extract pixels > 20 deg C)
107       # this stores the output map directly as GeoTIFF:
108       r.mapcalc "warm.tif = if(modis_celsius > 20.0, modis_celsius, null() )"
109       # cease GDAL output connection and turn back to write GRASS raster files:
110       r.external.out -r
111       # now use the resulting file elsewhere
112       gdalinfo $HOME/gisoutput/warm.tif
113

REFERENCES

115       GDAL Pages: http://www.gdal.org/
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AUTHOR

121       Glynn Clements
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SOURCE CODE

124       Available at: r.external.out source code (history)
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126       Accessed: Mon Jun 20 16:46:01 2022
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128       Main index | Raster index | Topics index | Keywords index  |  Graphical
129       index | Full index
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131       Â© 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
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135GRASS 8.2.0                                                  r.external.out(1)