v.import(1grass) GRASS GIS User's Manual v.import(1grass)
NAME
v.import - Imports vector data into a GRASS vector map using OGR li-
brary and reprojects on the fly.
KEYWORDS
vector, import, projection
SYNOPSIS
v.import
v.import --help
v.import [-flo] input=string [layer=string[,string,...]] [out-
put=name] [extent=string] [encoding=string] [snap=float]
[epsg=integer] [datum_trans=integer] [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
Flags:
-f
List supported OGR formats and exit
-l
List available OGR layers in data source and exit
-o
Override projection check (use current location’s projection)
Assume that the dataset has the same projection as the current lo-
cation
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
input=string [required]
Name of OGR datasource to be imported
layer=string[,string,...]
OGR layer name. If not given, all available layers are imported
output=name
Name for output vector map (default: input)
extent=string
Output vector map extent
Options: input, region
Default: input
input: extent of input map
region: extent of current region
encoding=string
Encoding value for attribute data
snap=float
Snapping threshold for boundaries (map units)
A suitable threshold is estimated during import
Default: -1
epsg=integer
EPSG projection code
Options: 1-1000000
datum_trans=integer
Index number of datum transform parameters
-1 to list available datum transform parameters
Options: -1-100
DESCRIPTION
v.import imports vector data from files and database connections sup-
ported by the OGR library) into the current location and mapset. If the
projection of the input does not match the projection of the location,
the input is reprojected into the current location. In case that the
projection of the input map does match the projection of the location,
the input is imported directly.
Supported Vector Formats
v.import uses the OGR library which supports various vector data for-
mats including ESRI Shapefile, Mapinfo File, UK .NTF, SDTS, TIGER, IHO
S-57 (ENC), DGN, GML, GPX, AVCBin, REC, Memory, OGDI, and PostgreSQL,
depending on the local OGR installation. For details see the OGR web
site. The OGR (Simple Features Library) is part of the GDAL library,
hence GDAL needs to be installed to use v.in.ogr.
The list of actually supported formats can be printed by -f flag.
NOTES
v.import checks the projection metadata of the dataset to be imported
against the current location’s projection. If not identical a related
error message is shown.
To override this projection check (i.e. to use current location’s pro-
jection) by assuming that the dataset has the same projection as the
current location the -o flag can be used. This is also useful when geo-
data to be imported do not contain any projection metadata at all. The
user must be sure that the projection is identical in order to avoid to
introduce data errors.
Topology cleaning
When importing polygons, non-topological polygons are converted to
topological areas. If the input polygons contain errors (unexpected
overlapping areas, small gaps between polygons, or warnings about being
unable to calculate centroids), the import might need to be repeated
using a snap value as suggested in the output messages. The default
value of snap=-1 means that no snapping will be done.
The snap threshold defines the maximal distance from one to another
vertex in map units (for latitude-longitude locations in degrees). If
there is no other vertex within snap distance, no snapping will be
done. Note that a too large value can severely damage area topology,
beyond repair.
Post-processing: Snapped boundaries may need to be cleaned with
v.clean, using its tools break,rmdupl,rmsa. For details, refer to the
v.clean manual page.
EXAMPLE
# import SHAPE file at full extent and reproject to current location projection
v.import input=research_area.shp output=research_area extent=input
ERROR MESSAGES
SQL syntax errors
Depending on the currently selected SQL driver, error messages such as
follows may arise:
DBMI-SQLite driver error:
Error in sqlite3_prepare():
near "ORDER": syntax error
Or:
DBMI-DBF driver error:
SQL parser error:
syntax error, unexpected DESC, expecting NAME processing ’DESC
This indicates that a column name in the input dataset corresponds to a
reserved SQL word (here: ’ORDER’ and ’DESC’ respectively). A different
column name has to be used in this case. The columns parameter can be
used to assign different column names on the fly in order to avoid us-
ing reserved SQL words. For a list of SQL reserved words for SQLite
(the default driver), see here.
Projection errors
Projection of dataset does not appear to match the current location.
Here you need to create or use a location whose projection matches that
of the vector data you wish to import. Try using location parameter to
create a new location based upon the projection information in the
file. If desired, you can then re-project it to another location with
v.proj.
SEE ALSO
v.clean, v.in.lines, v.in.ogr, v.proj
AUTHORS
Markus Metz
Improvements: Martin Landa, Anna Petrasova
SOURCE CODE
Available at: v.import source code (history)
Accessed: unknown
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© 2003-2022 GRASS Development Team, GRASS GIS 7.8.7 Reference Manual
GRASS 7.8.7 v.import(1grass)
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