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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 - Imports vector data into a GRASS vector map using OGR library.


vector, import, OGR, topology, geometry, snapping, create location

SYNOPSIS --help [-flc2tojrewi] input=string [gdal_config=string] [gdal_doo=string] [layer=string[,string,...]] [output=name] [spatial=xmin,ymin,xmax,ymax[,xmin,ymin,xmax,ymax,...]] [where=sql_query] [min_area=float] [type=string[,string,...]] [snap=float] [location=name] [columns=name[,name,...]] [encoding=string] [key=string] [geometry=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


List supported OGR formats and exit
List available OGR layers in data source and exit
Do not clean polygons (not recommended)
Force 2D output even if input is 3D
Useful if input is 3D but all z coordinates are identical
Do not create attribute table
Override projection check (use current location's projection)
Assume that the dataset has the same projection as the current location
Perform projection check only and exit
Limit import to the current region
Extend region extents based on new dataset
Also updates the default region if in the PERMANENT mapset
Change column names to lowercase characters
Create the location specified by the "location" parameter and exit. Do not import the vector data.
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


input=string [required]
Name of OGR datasource to be imported
        ESRI Shapefile: directory containing shapefiles
        MapInfo File: directory containing mapinfo files
GDAL configuration options
Comma-separated list of key=value pairs
GDAL dataset open options
Comma-separated list of key=value pairs
OGR layer name. If not given, all available layers are imported
        ESRI Shapefile: shapefile name
        MapInfo File: mapinfo file name
Name for output vector map
Import subregion only
Format: xmin,ymin,xmax,ymax - usually W,S,E,N
WHERE conditions of SQL statement without 'where' keyword
Example: income < 1000 and population >= 10000
Minimum size of area to be imported (square meters)
Smaller areas and islands are ignored. Should be greater than snap^2
Default: 0.0001
Optionally change default input type
Options: point, line, boundary, centroid
point: import area centroids as points
line: import area boundaries as lines
boundary: import lines as area boundaries
centroid: import points as centroids
Snapping threshold for boundaries (map units)
'-1' for no snap
Default: -1
Name for new location to create
List of column names to be used instead of original names, first is used for category column
Encoding value for attribute data
Overrides encoding interpretation, useful when importing ESRI Shapefile
Name of column used for categories
If not given, categories are generated as unique values and stored in 'cat' column
Name of geometry column
If not given, all geometry columns from the input are used

Table of contents

DESCRIPTION imports vector data from files and database connections supported by the OGR library) into the current location and mapset.

If the layer parameter is not given, all available OGR layers are imported as separate GRASS layers into one GRASS vector map. If several OGR layer names are given, all these layers are imported as separate GRASS layers into one GRASS vector map.

The optional spatial parameter defines spatial query extents. This parameter allows the user to restrict the region to a spatial subset while importing the data. All vector features completely or partially falling into this rectangle subregion are imported. The -r current region flag is identical, but uses the current region settings as the spatial bounds (see g.region).

Supported Vector Formats 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 format overview. The -f prints a list of the vector formats supported by the system's OGR (Simple Features Library). The OGR (Simple Features Library) is part of the GDAL library, hence GDAL needs to be installed to use

The list of actually supported formats can be printed by -f flag.

Topology cleaning

Topology cleaning on areas is automatically performed, but may fail in special cases. In these cases, a snap threshold value is estimated from the imported vector data and printed out at the end. The vector data can then be imported again with the suggested snap threshold value which is incremented by powers of 10 until either an estimated upper limit for the threshold value is reached or the topology cleaning on areas was successful. In some cases, manual cleaning might be required or areas are truly overlapping, e.g. buffers created with non-topological software.

The min_area threshold value is being specified as area size in map units with the exception of latitude-longitude locations in which it is being specified solely in square meters.

The snap threshold value is used to snap boundary vertices to each other if the distance in map units between two vertices is not larger than the threshold. Snapping is by default disabled with -1. See also the v.clean manual.

Overlapping polygons

When importing overlapping polygons, the overlapping parts will become new areas with multiple categories, one unique category for each original polygon. An original polygon will thus be converted to multiple areas with the same shared category. These multiple areas will therefore also link to the same entry in the attribute table. A single category value may thus refer to multiple non-overlapping areas which together represent the original polygon overlapping with another polygon. The original polygon can be recovered by using v.extract with the desired category value or where statement and the -d flag to dissolve common boundaries.

Location Creation attempts to preserve projection information when importing datasets if the source format includes projection information, and if the OGR driver supports it. If the projection of the source dataset does not match the projection of the current location will report an error message ("Projection of dataset does not appear to match current location").

If the user wishes to ignore the difference between the apparent coordinate system of the source data and the current location, they may pass the -o flag to override the projection check.

If the user wishes to import the data with the full projection definition, it is possible to have automatically create a new location based on the projection and extents of the file being read. This is accomplished by passing the name to be used for the new location via the location parameter. Upon completion of the command, a new location will have been created (with only a PERMANENT mapset), and the vector map will have been imported with the indicated output name into the PERMANENT mapset.

An interesting wrapper command around is v.import which reprojects (if needed) the vector dataset during import to the projection of the current location.


Table column names: supported characters

The characters which are eligible for table column names are limited by the SQL standard. Supported are:
This means that SQL neither supports '.' (dots) nor '-' (minus) nor '#' in table column names. Also a table name must start with a character, not a number. converts '.', '-' and '#' to '_' (underscore) during import. The -w flag changes capital column names to lowercase characters as a convenience for SQL usage (lowercase column names avoid the need to quote them if the attribute table is stored in a SQL DBMS such as PostgreSQL). The columns parameter is used to define new column names during import.

The DBF database specification limits column names to 10 characters. If the default DB is set to DBF and the input data contains longer column/field names, they will be truncated. If this results in multiple columns with the same name then will produce an error. In this case you will either have to modify the input data or use's columns parameter to rename columns to something unique. (hint: copy and modify the list given with the error message). Alternatively, change the local DB with db.connect.

File encoding

When importing ESRI Shapefiles the OGR library tries to read the LDID/codepage setting from the .dbf file and use it to translate string fields to UTF-8. LDID "87 / 0x57" is treated as ISO8859_1 which may not be appropriate for many languages. Unfortunately it is not clear what other values may be appropriate (see example below). To change encoding the user can set up SHAPE_ENCODING environmental variable or simply to define encoding value using encoding parameter.

Value for encoding also affects text recoding when importing DXF files. For other formats has encoding value no effect.

Defining the key column

Option key specifies the column name used for feature categories. This column must be integer. If not specified, categories numbers are generated starting with 1 and stored in the column named "cat".

Supports of multiple geometry columns

Starting with GDAL 1.11 the library supports multiple geometry columns in OGR. By default reads all geometry columns from given layer. The user can choose desired geometry column by geometry option, see example below.

Latitude-longitude data: Vector postprocessing after import

For vector data like a grid, horizontal lines need to be broken at their intersections with vertical lines (v.clean ... tool=break).


The command imports various vector formats:

SHAPE files input=/home/user/shape_data/test_shape.shp output=grass_map 
Alternate method: input=/home/user/shape_data layer=test_shape output=grass_map 
Define encoding value for attribute data (in this example we expect attribute data in Windows-1250 encoding; ie. in Central/Eastern European languages that use Latin script, Microsoft Windows encoding). input=/home/user/shape_data/test_shape.shp output=grass_map encoding=cp1250

MapInfo files input=./ layer=mapinfo_test output=grass_map

Arc Coverage

We import the Arcs and Label points, the module takes care to build areas. input=gemeinden layer=LAB,ARC type=centroid,boundary output=mymap

E00 file

See also

First we have to convert the E00 file to an Arc Coverage with 'avcimport' (AVCE00 tools, use e00conv first in case that avcimport fails):

avcimport e00file coverage input=coverage layer=LAB,ARC type=centroid,boundary output=mymap

SDTS files

You have to select the CATD file. input=CITXCATD.DDF output=cities

TIGER files input=input/2000/56015/ layer=CompleteChain,PIP output=t56015_all \
type=boundary,centroid snap=-1

PostGIS tables

Import polygons as areas: input="PG:host=localhost dbname=postgis user=postgres" layer=polymap \
output=polygons type=boundary,centroid
If the table containing the polygons are in a specific schema, you can use: input="PG:host=localhost dbname=postgis user=postgres" \
layer=myschema.polymap \
output=polygons type=boundary,centroid
Generally, just follows the format-specific syntax defined by the OGR library.

OpenStreetMap (OSM)

OSM data are available in .osm (XML based) and .pbf (optimized binary) formats. The .pbf format is recommended because file sizes are smaller. The OSM driver will categorize features into 5 layers : It is recommended to import one layer at a time, and to select features with the where option, e.g. to import roads, use where="highway <> ''"
i.e. the OSM tag highway must be set.

When importing administrative boundaries from OSM, it is important to not only select administrative boundaries, but also the admin level to be imported (valid range is 1 - 11), e.g. with where="boundary = 'administrative' and admin_level = '1'"

The OSM topological model differs from the GRASS topological model. OSM topologically correct connections of lines can be on all vertices of a line. During import, lines are automatically split at those vertices where an OSM connection to another line exists.

Import of OSM data requires a configuration file, defined with the OSM_CONFIG_FILE configuration option. In the data folder of the GDAL distribution, you can find a osmconf.ini file that can be customized to fit your needs. See OSM map features for keys and their values. You should set "other_tags=no" to avoid problems with import or querying the imported vector. Once a OSM_CONFIG_FILE has been created, OSM data can be imported with e.g.

export OSM_CONFIG_FILE=/path/to/osmconf.ini input=name.pbf layer=lines output=osm_data

Oracle Spatial

Note that you have to set the environment-variables ORACLE_BASE, ORACLE_SID, ORACLE_HOME and TNS_ADMIN accordingly. input=OCI:username/password@database_instance output=grasslayer layer=roads_oci

Multiple geometry columns

This example shows how to work with data which contain multiple geometry per feature. The number of geometry columns per feature can be checked by v.external together with -t flag.
v.external -t input=20141130_ST_UKSH.xml.gz
In our example layer "Okresy" has three geometry columns: "DefinicniBod", "OriginalniHranice" and "GeneralizovanaHranice". By default reads data from all three geometry columns. The user can specify desired geometry column by geometry option, in this case the module will read geometry only from the specified geometry column. In the example below, the output vector map will contain only geometry saved in "OriginalniHranice" geometry column. input=20141130_ST_UKSH.xml.gz layer=Okresy geometry=OriginalniHranice


If a message like
WARNING: Area size 1.3e-06, area not imported
appears, the min_area may be adjusted to a smaller value so that all areas are imported. Otherwise tiny areas are filtered out during import (useful to polish digitization errors or non-topological data).

If a message like

Try to import again, snapping with at least 1e-008: 'snap=1e-008'
appears, then the map to be imported contains topological errors. The message suggests a value for the snap parameter to be tried. For more details, see above in Topology Cleaning.


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
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 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.



db.connect, v.clean, v.extract,, v.edit, v.external, v.import,,, v.out.ogr

GRASS GIS Wiki page: Import of Global datasets


Original author: Radim Blazek, ITC-irst, Trento, Italy
Location and spatial extent support by Markus Neteler and Paul Kelly
Various improvements by Markus Metz
Multiple geometry columns support by Martin Landa, OSGeoREL, Czech Technical University in Prague, Czech Republic


Available at: source code (history)

Latest change: Wednesday Jan 27 21:15:26 2021 in commit: 2cf7e08b679327053f39d01060dd6a9e08e34f71

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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