1r.import(1)                   Grass User's Manual                  r.import(1)
2
3
4

NAME

6       r.import   -  Imports  raster  data  into a GRASS raster map using GDAL
7       library and reprojects on the fly.
8

KEYWORDS

10       raster, import, projection
11

SYNOPSIS

13       r.import
14       r.import --help
15       r.import  [-enlo]  input=name    [band=integer[,integer,...]]     [mem‐
16       ory=integer]     [output=name]     [resample=string]    [extent=string]
17       [resolution=string]       [resolution_value=float]       [title=phrase]
18       [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]
19
20   Flags:
21       -e
22           Estimate resolution only
23
24       -n
25           Do not perform region cropping optimization
26
27       -l
28           Force  Lat/Lon  maps  to  fit  into  geographic coordinates (90N,S;
29           180E,W)
30
31       -o
32           Override projection check (use current location’s projection)
33           Assume that the dataset has the  same  projection  as  the  current
34           location
35
36       --overwrite
37           Allow output files to overwrite existing files
38
39       --help
40           Print usage summary
41
42       --verbose
43           Verbose module output
44
45       --quiet
46           Quiet module output
47
48       --ui
49           Force launching GUI dialog
50
51   Parameters:
52       input=name [required]
53           Name of GDAL dataset to be imported
54
55       band=integer[,integer,...]
56           Input band(s) to select (default is all bands)
57
58       memory=integer
59           Maximum memory to be used (in MB)
60           Cache size for raster rows
61           Default: 300
62
63       output=name
64           Name for output raster map
65
66       resample=string
67           Resampling method to use for reprojection
68           Options:  nearest,  bilinear,  bicubic,  lanczos, bilinear_f, bicu‐
69           bic_f, lanczos_f
70           Default: nearest
71           nearest: nearest neighbor
72           bilinear: bilinear interpolation
73           bicubic: bicubic interpolation
74           lanczos: lanczos filter
75           bilinear_f: bilinear interpolation with fallback
76           bicubic_f: bicubic interpolation with fallback
77           lanczos_f: lanczos filter with fallback
78
79       extent=string
80           Output raster map extent
81           Options: input, region
82           Default: input
83           input: extent of input map
84           region: extent of current region
85
86       resolution=string
87           Resolution of output raster map (default: estimated)
88           Options: estimated, value, region
89           Default: estimated
90           estimated: estimated resolution
91           value: user-specified resolution
92           region: current region resolution
93
94       resolution_value=float
95           Resolution of output raster map (use with option resolution=value)
96
97       title=phrase
98           Title for resultant raster map
99

DESCRIPTION

101       r.import imports a map or selected bands from a GDAL raster  datasource
102       into  the  current  location and mapset. If the projection of the input
103       does not match the projection of the location, the input is reprojected
104       into  the  current  location. If the projection of the input does match
105       the projection of the location, the input  is  imported  directly  with
106       r.in.gdal.
107

NOTES

109       r.import  checks  the projection metadata of the dataset to be imported
110       against the current location’s projection. If not identical  a  related
111       error message is shown.
112       To  override this projection check (i.e. to use current location’s pro‐
113       jection) by assuming that the dataset has the same  projection  as  the
114       current location the -o flag can be used. This is also useful when geo‐
115       data to be imported do not contain any projection metadata at all.  The
116       user must be sure that the projection is identical in order to avoid to
117       introduce data errors.
118
119   Resolution
120       r.import reports the estimated target resolution for each  input  band.
121       The  estimated  resolution  will usually be some floating point number,
122       e.g. 271.301. In case option resolution is set to estimated  (default),
123       this floating point number will be used as target resolution. Since the
124       target resolution should be typically the rounded estimated resolution,
125       e.g. 250 or 300 instead of 271.301, flag -e can be used first to obtain
126       the estimate without importing the raster bands.  Then the desired res‐
127       olution   is  set  with  option  resolution_value  and  option  resolu‐
128       tion=value.  For latlong locations, the resolution might be set to  arc
129       seconds, e.g. 1, 3, 7.5, 15, and 30 arc seconds are commonly used reso‐
130       lutions.
131
132   Resampling methods
133       When reprojecting a map to a new spatial  reference  system,  the  pro‐
134       jected  data  is  resampled with one of four different methods: nearest
135       neighbor, bilinear, bicubic iterpolation or lanczos.
136
137       In the following common use cases:
138
139       nearest is the simplest method and the only possible method  for  cate‐
140       gorical data.
141
142       bilinear  does  linear  interpolation and provides smoother output than
143       nearest. bilinear is recommended when reprojecting a DEM for hydrologi‐
144       cal  analysis  or  for  surfaces where overshoots must be avoided, e.g.
145       precipitation should not become negative.
146
147       bicubic produces smoother output than bilinear, at the  cost  of  over‐
148       shoots.
149
150       lanczos produces the smoothest output of all methods and preserves con‐
151       trast best. lanczos is recommended for imagery.  Both bicubic and lanc‐
152       zos preserve linear features. With nearest or bilinear, linear features
153       can become zigzag features after reprojection.
154
155       For explanation of the -l flag, please refer to the r.in.gdal manual.
156
157       When importing whole-world maps the user  should  disable  map-trimming
158       with the -n flag. For further explanations of -n flag, please refer the
159       to r.proj manual.
160

EXAMPLES

162   Import of SRTM V3 global data at 1 arc-seconds resolution
163       The SRTM V3 1 arc-second global data (~30 meters resolution) are avail‐
164       able  from  EarthExplorer  (http://earthexplorer.usgs.gov/).   The SRTM
165       collections are located under the "Digital Elevation" category.
166
167       Example  for  North  Carolina  sample  dataset  (the   tile   name   is
168       "n35_w079_1arc_v3.tif"):
169       # set computational region to e.g. 10m elevation model:
170       g.region raster=elevation -p
171       # Import with reprojection on the fly. Recommended parameters:
172       # resample   Resampling method to use for reprojection - bilinear
173       # extent     Output raster map extent - region: extent of current region
174       # resolution Resolution of output raster map
175       #  - region: current region resolution - limit to g.region setting from above
176       r.import input=n35_w079_1arc_v3.tif output=srtmv3_resamp10m resample=bilinear \
177         extent=region resolution=region title="SRTM V3 resampled to 10m resolution"
178       # beautify colors:
179       r.colors srtmv3_resamp10m color=elevation
180
181   Import of WorldClim data
182       Import  of  a subset from WorldClim Bioclim data set, to be reprojected
183       to current location projection (North Carolina sample  dataset).   Dif‐
184       ferent  resolutions  are  available,  in  this  example  we use the 2.5
185       arc-minutes resolution data. During import,  we  spatially  subset  the
186       world data to the North Carolina region using the extent parameter:
187       # download selected Bioclim data (2.5 arc-minutes resolution)
188       # optionally tiles are available for the 30 arc-sec resolution
189       wget http://biogeo.ucdavis.edu/data/climate/worldclim/1_4/grid/cur/bio_2-5m_bil.zip
190       # extract BIO1 from package (BIO1 = Annual Mean Temperature):
191       unzip bio_2-5m_bil.zip bio1.bil bio1.hdr
192       # prior to import, fix broken WorldClim extent using GDAL tool
193       gdal_translate -a_ullr -180 90 180 -60 bio1.bil bio1_fixed.tif
194       # set computational region to North Carolina, 4000 m target pixel resolution
195       g.region -d res=4000 -ap
196       # subset to current region and reproject on the fly to current location projection,
197       # using -n since whole-world map is imported:
198       r.import input=bio1_fixed.tif output=bioclim01 resample=bilinear \
199                extent=region resolution=region -n
200       # temperature data are in °C * 10
201       r.info bioclim01
202       r.univar -e bioclim01
203

SEE ALSO

205        r.in.gdal, r.proj
206

AUTHORS

208       Markus Metz
209       Improvements: Martin Landa, Anna Petrasova
210

SOURCE CODE

212       Available at: r.import source code (history)
213
214       Main  index  | Raster index | Topics index | Keywords index | Graphical
215       index | Full index
216
217       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual
218
219
220
221GRASS 7.8.2                                                        r.import(1)
Impressum