PostGIS

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PostGIS

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Basic data

Maintainer Open Source Geospatial Foundation
developer Refractions Research
Current  version 3.0.0
( October 20, 2019 )
operating system GNU / Linux , POSIX  -compatible, Windows , macOS
programming language C.
category Geographic information system
License GPL ( Free Software )
German speaking No
postgis.net

PostGIS is an extension for the PostgreSQL object-relational database that includes geographic objects and functions. PostgreSQL with PostGIS forms a geodatabase that can be integrated into geographic information systems. The project implements the Simple Feature Access specification of the Open Geospatial Consortium and is supervised by the Open Source Geospatial Foundation .

history

PostGIS has been developed by Refractions Research since 2000. Although PostgreSQL itself already supports geometry types, according to the developers these are not sufficient to be able to comprehensively store and analyze spatial data. PostgreSQL offers the possibility to define your own data types. These good prerequisites were the main motivation to start developing a spatial extension for PostgreSQL.

The first version was released in May 2001 under the GNU General Public License and was numbered 0.1. This early version had the ability to load and query spatial objects, simple spatial functions, a spatial index for quick access to the data, and a JDBC extension to connect to Java .

With version 0.5, PostGIS was supplemented by the OpenGIS well-known binary format and the names of existing functions were adapted to the OpenGIS specifications.

In the following versions, numerous spatial functions and operators were added. Refractions Research began to combine these functions in a separate library called GEOS , which takes the OpenGIS specifications into account and is a C ++ port of the JTS Topology Suite . From version 0.8 PostGIS uses the GEOS library.

The next developments were aimed primarily in the direction of more efficient memory management. The new data structure was called light-weight geometry and from version 1.0 only this is used.

The current development of PostGIS is increasingly taking into account the ISO - SQL / MM specification, which includes more geometry types such as B. Curves implemented as the OpenGIS specification.

Version 2.0 uses the PostgreSQL extension system that has existed since PostgreSQL 9.1.

properties

PostGIS supports the following geometry types:

  • OpenGIS Well-Known Text or Well-Known Binary: Point, Linestring, Polygon, Multipoint, Multilinestring, Multipolygon and Geometrycollection
  • Extended Well-Known Text or Extended Well-Known Binary: extends OpenGIS Well-Known Text with height information and / or with a measured value
  • SQL / MM (not yet fully supported): Circularstring, Compoundcurve, Curvepolygon, Multicurve, Multisurface

Functions and operators supported by PostGIS:

  • Spatial functions such as calculation of areas and distances, intersection, calculation of buffer zones, etc.
  • Spatial operators such as overlaps, within, containers etc.
  • Functions for creating geometries
  • Analysis of raster and vector data
  • Functions for querying geometries in the formats Well-Known Text, Well-Known Binary, GML , SVG , KML
  • Spatial indexing with the GiST index

Access to geometry data

PostGIS is accessed using the same tools as PostgreSQL databases. Examples of open source programs for database administration are psql or pgAdmin . All existing PostgreSQL interfaces to various programming languages ​​can also be used to access PostGIS databases, such as B. a Java / JDBC connection or the C library libpq .

A number of GIS programs or libraries support PostGIS natively, such as B. GeoTools , MapServer , QGIS or GDAL / OGR .

Then there are the command line programs pgsql2shp and shp2pgsql which to convert ESRI - shapefiles are used inversely to PostGIS tables and. OpenStreetMap data can also be imported using osm2pgsql .

Extensions

WKT grid

WKT Raster is an extension to support raster data in PostGIS. The main feature of this extension is the introduction of a raster data type analogous to the existing Geometry data type.

Route planning

Functionalities for route planning can be added to PostGIS databases with the pgRouting module . PgRouting allows you to create topologies and solve the following problems:

Web links

Individual evidence

  1. ↑ git.osgeo.org .
  2. ^ PostGIS 3.0.0 .
  3. ↑ The postgis Open Source Project on Open Hub: Languages Page . In: Open Hub . (accessed on July 18, 2018).
  4. ^ PostGIS History. In: refractions.net. Retrieved July 10, 2017 (English).
  5. ^ PostGIS Raster Beta Documentation. In: OSGeo. March 10, 2012, accessed July 10, 2017 .
  6. ↑ pgRouting Project. In: pgrouting.org. Retrieved July 10, 2017 (English).