= The Sandbox =

This is just a page to practice and learn WikiFormatting. 

Go ahead, edit it freely.

!!What is PostGIS

PostGIS is an extension  to the  [http://www.postgresql.org/ PostgreSQL] object-relational database system that allows [http://en.wikipedia.org/wiki/Geographic_information_system/ GIS] (Geographic Information System) [[BR]]
objects to be stored in the database. PostGIS does for PostgreSQL what Oracle Spatial does for Oracle, ArcSDE does[[BR]]
 for Microsoft SQL Server/Oracle.

!!Overview

* [FeaturesOfPostgis/Features of PostGIS]
* [http://www.postgresonline.com/journal/index.php?/archives/7-PostGIS-for-geospatial-analysis-and-mapping.html/PostGIS as a part of PostgreSQL (Article)]
* [Tools that support PostGIS | ToolsSupportPostgis]
* [Gallery] Collection of applications using PostGIS in the backend.
* [PostgresqlCaseStudies | PostgreSQL Case Studies]
* [PostGIS Hosters | PostGISHosters]
* [PostGIS Wikipedia entry | http://en.wikipedia.org/wiki/PostGIS]
* [PostGIS and ArcSDE/ArcGIS 9.3 Articles | Postgisarcgis]

!!Installation Guides

* Directions for [PostGIS RPM Installation|PostgisRpmInstallation].
* Directions for [PostGIS on Ubuntu| PostgisOnUbuntu].

!!Examples of Spatial SQL

* [Find Nearby Features|ExamplesFindNearby]
* [Find Features far from nearest neighbor - Anti-Near Neighbor | ExamplesAntiNear]
* [Find Overlapping Features|ExamplesFindOverlapping]
* [Join Spatial and Non-Spatial Tables|ExamplesJoinTables]
* [Overlay Geometries in one table with Geometries in another|ExamplesOverlayTables]
* [Find Features Inside a Particular Polygon|ExamplesInsidePolygon]
* [Clean Invalid Polygon Topology|CleanPolygons]
** [Find points on interior rings within a certain distance to exterior ring|ExamplesInsidePolygon2]
* [Splitting a Polygon with a Linestring|SplitPolygonWithLineString]
* [Generating a hexagonal grid|GenerateHexagonalGrid]
* [MultiPoint centroids from Multi geometries |ComputeMultiCentroid]
* [OGR Examples]

!!Extending PostGIS

* [PostGIS EJB3 Integration| SpatialEJB3]
* PostgisTopology - to be moved somewhere else ;)
* [Raster support|RasterNotes]
** [WKT Raster - The new proposed raster implementation in PostGIS|WKTRasterHomePage]
** [PGCHIP - The GDAL Postgis driver for raster data | http://simon.benjamin.free.fr/pgchip/] - a corrected version can be found in current GDAL CVS
* [WishList] of features for the future
* [Code Sprint 2009 Notes|Sprint2009Notes]

!!Newbie Common Problems and Questions

* [function addgeometrycolumn("unknown", "unknown", integer, "unknown", integer) does not exist]
* [What is the measurement returned by ST_Distance?]
* [What unit of measurement do PostGIS functions use? | PostGISFunctionMeasurement]
* [How to get distance measurement in meters|distance_in_meters]

!!Extras

* [TigerGeocoder | Tiger Geocoder]

!!Summer of Code

* [SummerOfCode2006]

!!Notes

* SpatialAlgorithmWebSites

!!Useful Additional PL/PGSQL Functions
* [PL/PGSQL Functions|plpgsqlfunctions]
* [Nearest Neighbor Search]
* [PL/PGSQL Pseudo Cascade Union Aggregate Function | upgis_cascadeunion]

!!Known issues/patches pending review
* [IssuesPatchesPending]

!!What is GEOS

[GEOS] is a C++ port of the JTS Topology Suite.
It is used by PostGIS to implement Topological functions.

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