New PostGIS Functions

The functions given below are PostGIS functions that were introduced in this major release.

• Populate_Geometry_Columns – Ensures geometry columns have appropriate spatial constraints and exist in the geometry_columns table. Availability: 1.4.0
• ST_Collect – Return a specified ST_Geometry value from a collection of other geometries. Availability: 1.4.0 – ST_Collect(geomarray) was introduced. ST_Collect was enhanced to handle more geometries faster.
• ST_ContainsProperly – Returns true if B intersects the interior of A but not the boundary (or exterior). A does not contain properly itself, but does contain itself. Availability: 1.4.0 – requires GEOS >= 3.1.0.
• ST_GeoHash – Return a GeoHash representation (geohash.org) of the geometry. Availability: 1.4.0
• ST_IsValidReason – Returns text stating if a geometry is valid or not and if not valid, a reason why. Availability: 1.4 – requires GEOS >= 3.1.0.
• ST_LineCrossingDirection – Given 2 linestrings, returns a number between -3 and 3 denoting what kind of crossing behavior. 0 is no crossing. Availability: 1.4
• ST_LocateBetweenElevations – Return a derived geometry (collection) value with elements that intersect the specified range of elevations inclusively. Only 3D, 4D LINESTRINGS and MULTILINESTRINGS are supported. Availability: 1.4.0
• ST_MakeLine – Creates a Linestring from point geometries. Availability: 1.4.0 – ST_MakeLine(geomarray) was introduced. ST_MakeLine aggregate functions was enhanced to handle more points faster.
• ST_MinimumBoundingCircle – Returns the smallest circle polygon that can fully contain a geometry. Default uses 48 segments per quarter circle. Availability: 1.4.0 – requires GEOS
• ST_Union – Returns a geometry that represents the point set union of the Geometries. Availability: 1.4.0 – ST_Union was enhanced. ST_Union(geomarray) was introduced and also faster aggregate collection in PostgreSQL. If you are using GEOS 3.1.0+ ST_Union will use the faster Cascaded Union algorithm described in http://blog.cleverelephant.ca/2009/01/must-faster-unions-in-postgis-14.html

The functions given below are PostGIS functions that were introduced in the 1.3 release.

• ST_AsGeoJSON – Return the geometry as a GeoJSON element. Availability: 1.3.4
• ST_SimplifyPreserveTopology – Returns a “simplified” version of the given geometry using the Douglas-Peuker algorithm. Will avoid creating derived geometries (polygons in particular) that are invalid. Availability: 1.3.3