Importing vector data using ogr2ogr

ogr2ogr is the GDAL's vector transform utility. It is - not without reason - considered a Swiss Army knife for vector transformations. Despite its size, ogr2ogr can handle a wide range of formats and this makes it a really worthy tool.

We'll use ogr2ogr to import a few data formats other than SHP, although ogr2ogr can obviously import SHP too. For this scenario, we'll use some data downloaded earlier:

• OS GB address base in GML format
• OS GB code point polygons in MapInof MIF & TAB formats
• USGS earthquakes in KML format

Some of the most common ogr2ogr params are:

• -f: The format of the output (when importing to PostGIS it will be PostgreSQL).
• -nln: Assigns a name to the layer. In the case of importing the data to PostGIS this will be the table name.
• -select: Lets you specify a comma separated list of columns to pick.
• -where: Lets you specify a sql like query to filter out the data.
• append: Appends data to the output dataset.
• overwrite: Overwrites the output datasource - in case of PostgreSQL it will drop and re-create a table.
• s_srs: Specifies the input SRID.
• t_srs: Transforms coordinates to the specified SRID.
• a_srs: Specifies the output SRID.
  • lco NAME=VALUE: Layer creation options - these are driver specific; for pgsql options, see http://www.gdal.org/drv_pg.html. The most commonly used layer creation options are:
  • LAUNDER: This defaults to YES. It is responsible for converting column names into pgsql compatible ones (lower case, underscores).
  • PRECISION: This defaults to YES. It is responsible for using numeric and char types over float and varchar.
  • GEOMETRY_NAME: Defaults to wkb_geometry.