DESCRIPTION
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.
Supported Vector Formats
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.
NOTES
Topology cleaning
When importing polygons, non-topological polygons are converted to
topological areas. By default, a very small snapping threshold is applied
(1e-13 map units) to avoid topological errors caused by numerical inaccuracy
of the input data format. If the original polygons contain errors (unexpected
overlapping areas or small gaps between polygons), the import might
need to be repeated using a larger snap value.
The snap threshold defines the maximal distance from one to another
vertex in map units (for latitude-longitude locations in degree). 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
SEE ALSO
v.clean,
v.in.ogr,
v.proj
AUTHORS
Markus Metz
Improvements: Martin Landa, Anna Petrasova
Last changed: $Date$