Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.
NAME
v.import - Imports vector data into a GRASS vector map using OGR library and reprojects on the fly.
KEYWORDS
vector,
import,
projection
SYNOPSIS
v.import
v.import --help
v.import [-flo] input=string [layer=string[,string,...]] [output=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 location
- --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
v.import imports vector data from files and database connections
supported 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.
v.import uses the OGR library which supports various vector data
formats 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.
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 projection)
by assuming that the dataset has the same projection as the current location
the
-o flag can be used. This is also useful when geodata 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.
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.
# import SHAPE file at full extent and reproject to current location projection
v.import input=research_area.shp output=research_area extent=input
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 using reserved SQL words.
For a list of SQL reserved words for SQLite (the default driver),
see
here.
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.
v.clean,
v.in.lines,
v.in.ogr,
v.proj
Markus Metz
Improvements: Martin Landa, Anna Petrasova
SOURCE CODE
Available at:
v.import source code
(history)
Latest change: Sat Feb 20 11:06:03 2021 in commit: eafabb743aa3bea1b4e09baf84ed860dbcd1fe2c
Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.
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© 2003-2023
GRASS Development Team,
GRASS GIS 7.8.8dev Reference Manual