1v.import(1) GRASS GIS User's Manual v.import(1)
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6 v.import - Imports vector data into a GRASS vector map using OGR li‐
7 brary and reprojects on the fly.
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10 vector, import, projection
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13 v.import
14 v.import --help
15 v.import [-flo] input=string [layer=string[,string,...]] [out‐
16 put=name] [extent=string] [encoding=string] [snap=float]
17 [epsg=integer] [datum_trans=integer] [--overwrite] [--help]
18 [--verbose] [--quiet] [--ui]
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20 Flags:
21 -f
22 List supported OGR formats and exit
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24 -l
25 List available OGR layers in data source and exit
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27 -o
28 Override projection check (use current location’s projection)
29 Assume that the dataset has the same projection as the current lo‐
30 cation
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32 --overwrite
33 Allow output files to overwrite existing files
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35 --help
36 Print usage summary
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38 --verbose
39 Verbose module output
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41 --quiet
42 Quiet module output
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44 --ui
45 Force launching GUI dialog
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47 Parameters:
48 input=string [required]
49 Name of OGR datasource to be imported
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51 layer=string[,string,...]
52 OGR layer name. If not given, all available layers are imported
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54 output=name
55 Name for output vector map (default: input)
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57 extent=string
58 Output vector map extent
59 Options: input, region
60 Default: input
61 input: extent of input map
62 region: extent of current region
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64 encoding=string
65 Encoding value for attribute data
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67 snap=float
68 Snapping threshold for boundaries (map units)
69 A suitable threshold is estimated during import
70 Default: -1
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72 epsg=integer
73 EPSG projection code
74 Options: 1-1000000
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76 datum_trans=integer
77 Index number of datum transform parameters
78 -1 to list available datum transform parameters
79 Options: -1-100
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82 v.import imports vector data from files and database connections sup‐
83 ported by the OGR library) into the current location and mapset. If the
84 projection of the input does not match the projection of the location,
85 the input is reprojected into the current location. In case that the
86 projection of the input map does match the projection of the location,
87 the input is imported directly.
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89 Supported Vector Formats
90 v.import uses the OGR library which supports various vector data for‐
91 mats including ESRI Shapefile, Mapinfo File, UK .NTF, SDTS, TIGER, IHO
92 S-57 (ENC), DGN, GML, GPX, AVCBin, REC, Memory, OGDI, and PostgreSQL,
93 depending on the local OGR installation. For details see the OGR web
94 site. The OGR (Simple Features Library) is part of the GDAL library,
95 hence GDAL needs to be installed to use v.import.
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97 The list of actually supported formats can be printed by -f flag.
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100 v.import checks the projection metadata of the dataset to be imported
101 against the current location’s projection. If not identical a related
102 error message is shown.
103 To override this projection check (i.e. to use current location’s pro‐
104 jection) by assuming that the dataset has the same projection as the
105 current location the -o flag can be used. This is also useful when geo‐
106 data to be imported do not contain any projection metadata at all. The
107 user must be sure that the projection is identical in order to avoid to
108 introduce data errors.
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110 Topology cleaning
111 When importing polygons, non-topological polygons are converted to
112 topological areas. If the input polygons contain errors (unexpected
113 overlapping areas, small gaps between polygons, or warnings about being
114 unable to calculate centroids), the import might need to be repeated
115 using a snap value as suggested in the output messages. The default
116 value of snap=-1 means that no snapping will be done.
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118 The snap threshold defines the maximal distance from one to another
119 vertex in map units (for latitude-longitude locations in degrees). If
120 there is no other vertex within snap distance, no snapping will be
121 done. Note that a too large value can severely damage area topology,
122 beyond repair.
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124 Post-processing: Snapped boundaries may need to be cleaned with
125 v.clean, using its tools break,rmdupl,rmsa. For details, refer to the
126 v.clean manual page.
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129 # import SHAPE file at full extent and reproject to current location projection
130 v.import input=research_area.shp output=research_area extent=input
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133 SQL syntax errors
134 Depending on the currently selected SQL driver, error messages such as
135 follows may arise:
136 DBMI-SQLite driver error:
137 Error in sqlite3_prepare():
138 near "ORDER": syntax error
139 Or:
140 DBMI-DBF driver error:
141 SQL parser error:
142 syntax error, unexpected DESC, expecting NAME processing ’DESC
143 This indicates that a column name in the input dataset corresponds to a
144 reserved SQL word (here: ’ORDER’ and ’DESC’ respectively). A different
145 column name has to be used in this case. The columns parameter can be
146 used to assign different column names on the fly in order to avoid us‐
147 ing reserved SQL words. For a list of SQL reserved words for SQLite
148 (the default driver), see here.
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150 Projection errors
151 Projection of dataset does not appear to match the current location.
152 Here you need to create or use a location whose projection matches that
153 of the vector data you wish to import. Try using location parameter to
154 create a new location based upon the projection information in the
155 file. If desired, you can then re-project it to another location with
156 v.proj.
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159 v.clean, v.in.lines, v.in.ogr, v.proj
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162 Markus Metz
163 Improvements: Martin Landa, Anna Petrasova
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166 Available at: v.import source code (history)
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168 Accessed: Saturday Jan 21 21:17:03 2023
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170 Main index | Vector index | Topics index | Keywords index | Graphical
171 index | Full index
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173 © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
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177GRASS 8.2.1 v.import(1)