Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here
NAME
v.external - Creates a new pseudo-vector map as a link to an OGR-supported layer or a PostGIS feature table.
KEYWORDS
vector,
import,
external,
OGR,
PostGIS
SYNOPSIS
v.external
v.external --help
v.external [-fltb] input=string layer=name [output=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -f
- List supported formats and exit
- -l
- List available layers in data source and exit
- -t
- List available layers including feature type in data source and exit
- Format: layer name,type,projection check,geometry
- -b
- Do not build topology
- --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 input OGR or PostGIS data source
- Examples:
ESRI Shapefile: directory containing a shapefile
MapInfo File: directory containing a mapinfo file
PostGIS database: connection string, eg. 'PG:dbname=db user=grass'
- layer=name [required]
- Name of OGR layer or PostGIS feature table to be linked
- Examples:
ESRI Shapefile: shapefile name
MapInfo File: mapinfo file name
PostGIS database: table name
- output=name
- Name for output GRASS vector map (default: input layer)
v.external creates new vector map as a link to external OGR
layer or PostGIS feature table. OGR (Simple Features Library) is part
of the
GDAL library, so you need to install
GDAL to use
v.external for external OGR layers. Note that a
PostGIS feature table can be linked also using built-in
GRASS-PostGIS
data driver (requires GRASS to be built with PostgreSQL support).
To list supported OGR formats, type
For details see
OGR web site.
Assuming that 'test_shape.shp' is located in directory
'/home/user/shape_data'.
v.external input=/home/user/shape_data layer=test_shape output=grass_map
v.external input=./ layer=mapinfo_test output=grass_map
Note: you have to select the CATD file
v.external input=CITXCATD.DDF output=cities
v.external input=input/2000/56015/ layer=CompleteChain,PIP output=t56015_all
PostGIS links are by default created by built-in PostGIS support,
ie. using
GRASS-PostGIS data driver. If the environment
variable
GRASS_VECTOR_OGR exists, or GRASS is compiled
without PostgreSQL support then GRASS will use OGR-PostgreSQL driver
for creating a link.
v.external input="PG:host=localhost user=postgres dbname=postgis" layer=polymap
The simple feature data model used by OGR (or PostGIS) is very
different from the topological format used by GRASS. Instead of true
topology, so called 'pseudo topology' is created for data linked by
v.external. User should learn the difference between those
two formats, because some modules working correctly with GRASS native
data, can produce wrong results with input vector maps created
by
v.external.
See v.db.connect for an example of
maintaining attributes in external DBMS in also writable mode.
OGR vector library C API documentation
v.external.out,
v.clean,
v.db.connect,
v.import,
v.in.db,
v.in.ogr,
v.out.ogr
OGR Library
PostGIS
See
also GRASS user wiki page for more examples.
Radim Blazek, ITC-Irst, Trento, Italy
PostGIS support by Martin Landa, Czech Technical University in Prague, Czech Republic
Last changed: $Date: 2016-01-13 01:20:46 -0800 (Wed, 13 Jan 2016) $
SOURCE CODE
Available at: v.external source code (history)
Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here
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GRASS Development Team,
GRASS GIS 7.0.7svn Reference Manual