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NAME

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

KEYWORDS

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

SYNOPSIS

v.in.ogr
v.in.ogr --help
v.in.ogr [-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] [project=name] [columns=name[,name,...]] [encoding=string] [key=string] [geometry=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-f
List supported OGR formats and exit
-l
List available OGR layers in data source and exit
-c
Do not clean polygons (not recommended)
-2
Force 2D output even if input is 3D
Useful if input is 3D but all z coordinates are identical
-t
Do not create attribute table
-o
Override projection check (use current project's CRS)
Assume that the dataset has the same coordinate reference system (CRS) as the current project
-j
Perform projection check only and exit
-r
Limit import to the current region
-e
Extend region extents based on new dataset
Also updates the default region if in the PERMANENT mapset
-w
Change column names to lowercase characters
-i
Create the project specified by the "project" parameter and exit. Do not import the vector data.
--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
Examples:
        ESRI Shapefile: directory containing shapefiles
        MapInfo File: directory containing mapinfo files
gdal_config=string
GDAL configuration options
Comma-separated list of key=value pairs
gdal_doo=string
GDAL dataset open options
Comma-separated list of key=value pairs
layer=string[,string,...]
OGR layer name. If not given, all available layers are imported
Examples:
        ESRI Shapefile: shapefile name
        MapInfo File: mapinfo file name
output=name
Name for output vector map
spatial=xmin,ymin,xmax,ymax[,xmin,ymin,xmax,ymax,...]
Import subregion only
Format: xmin,ymin,xmax,ymax - usually W,S,E,N
where=sql_query
WHERE conditions of SQL statement without 'where' keyword
Example: income < 1000 and population >= 10000
min_area=float
Minimum size of area to be imported (square meters)
Smaller areas and islands are ignored. Should be greater than snap^2
Default: 0.0001
type=string[,string,...]
Optionally change default input type
Options: point, line, boundary, centroid
Default:
point: import area centroids as points
line: import area boundaries as lines
boundary: import lines as area boundaries
centroid: import points as centroids
snap=float
Snapping threshold for boundaries (map units)
'-1' for no snap
Default: -1
project=name
Name for new project (location) to create
columns=name[,name,...]
List of column names to be used instead of original names, first is used for category column
encoding=string
Encoding value for attribute data
Overrides encoding interpretation, useful when importing ESRI Shapefile
key=string
Name of column used for categories
If not given, categories are generated as unique values and stored in 'cat' column
geometry=name
Name of geometry column
If not given, all geometry columns from the input are used

Table of contents

DESCRIPTION

v.in.ogr imports vector data from files and database connections supported by the OGR library) into the current project (previously called 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

v.in.ogr 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 v.in.ogr.

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 projects 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.

Project Creation

v.in.ogr attempts to preserve coordinate reference system (CRS) information when importing datasets if the source format includes such information, and if the OGR driver supports it. If the CRS of the source dataset does not match the CRS of the current project v.in.ogr will report an error message ("Coordinate reference system of dataset does not appear to match current project").

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

If the user wishes to import the data with the full CRS definition, it is possible to have v.in.ogr automatically create a new project based on the CRS and extents of the file being read. This is accomplished by passing the name to be used for the new project via the project parameter. Upon completion of the command, a new project 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 v.in.ogr is v.import which reprojects (if needed) the vector dataset during import to the CRS of the current project.

NOTES

Table column names: supported characters

The characters which are eligible for table column names are limited by the SQL standard. Supported are: 
[A-Za-z][A-Za-z0-9_]*
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.

v.in.ogr 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 v.in.ogr will produce an error. In this case you will either have to modify the input data or use v.in.ogr'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 v.in.ogr 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).

EXAMPLES

The command imports various vector formats:

SHAPE files

v.in.ogr input=/home/user/shape_data/test_shape.shp output=grass_map
Alternate method: 
v.in.ogr 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). 
v.in.ogr input=/home/user/shape_data/test_shape.shp output=grass_map encoding=cp1250

MapInfo files

v.in.ogr input=./ layer=mapinfo_test output=grass_map

Arc Coverage

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

E00 file

See also v.in.e00.

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
v.in.ogr input=coverage layer=LAB,ARC type=centroid,boundary output=mymap

SDTS files

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

TIGER files

v.in.ogr input=input/2000/56015/ layer=CompleteChain,PIP output=t56015_all \
type=boundary,centroid snap=-1

PostGIS tables

Import polygons as areas: 
v.in.ogr 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: 
v.in.ogr input="PG:host=localhost dbname=postgis user=postgres" \
layer=myschema.polymap \
output=polygons type=boundary,centroid
Generally, v.in.ogr 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 
v.in.ogr 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 

v.in.ogr 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
v.in.ogr 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. 
v.in.ogr 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
...
Okresy,point,1,DefinicniBod
Okresy,multipolygon,1,OriginalniHranice
Okresy,multipolygon,1,GeneralizovaneHranice
...
In our example layer "Okresy" has three geometry columns: "DefinicniBod", "OriginalniHranice" and "GeneralizovanaHranice". By default v.in.ogr 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. 
v.in.ogr input=20141130_ST_UKSH.xml.gz layer=Okresy geometry=OriginalniHranice

WARNINGS

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.

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 using reserved SQL words. For a list of SQL reserved words for SQLite (the default driver), see here.

Projection errors

Coordinate reference system of dataset does not appear to match the current project.
Here you need to create or use a project whose CRS matches that of the vector data you wish to import. Try using project parameter to create a new project based upon the CRS information in the file. If desired, you can then reproject it to another project with v.proj.

REFERENCES

SEE ALSO

db.connect, v.clean, v.extract, v.build.polylines, v.edit, v.external, v.import, v.in.db, v.in.e00, v.out.ogr

GRASS GIS Wiki page: Import of Global datasets

AUTHORS

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

SOURCE CODE

Available at: v.in.ogr source code (history)

Latest change: Wednesday Oct 23 17:12:02 2024 in commit: 533070dbc9807657e96ec376f23ab6db64fbdc9a

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