PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual270 / 310• ST_Union - Returns a geometry that represents the point set union of the Geometries. This method implements the SQL/MMspecification. SQL-MM 3: 5.1.19 the z-index (elevation) when polygons are involved.• ST_WKBToSQL - Return a specified ST_Geometry value from Well-Known Binary representation (WKB). This is an aliasname for ST_GeomFromWKB that takes no srid This method implements the SQL/MM specification. SQL-MM 3: 5.1.36• ST_WKTToSQL - Return a specified ST_Geometry value from Well-Known Text representation (WKT). This is an alias namefor ST_GeomFromText This method implements the SQL/MM specification. SQL-MM 3: 5.1.34• ST_Within - Returns true if the geometry A is completely inside geometry B This method implements the SQL/MM specification.SQL-MM 3: 5.1.30• ST_X - Return the X coordinate of the point, or NULL if not available. Input must be a point. This method implements theSQL/MM specification. SQL-MM 3: 6.1.3• ST_Y - Return the Y coordinate of the point, or NULL if not available. Input must be a point. This method implements theSQL/MM specification. SQL-MM 3: 6.1.4• ST_Z - Return the Z coordinate of the point, or NULL if not available. Input must be a point. This method implements theSQL/MM specification.8.3 PostGIS Geography Support FunctionsThe functions and operators given below are PostGIS functions/operators that take as input or return as output a geography datatype object.NoteFunctions with a (T) are not native geodetic functions, and use a ST_Transform call to and from geometry to do theoperation. As a result, they may not behave as expected when going over dateline, poles, and for large geometries orgeometry pairs that cover more than one UTM zone. Basic tranform - (favoring UTM, Lambert Azimuthal (North/South),and falling back on mercator in worst case scenario)• ST_Area - Returns the area of the surface if it is a polygon or multi-polygon. For "geometry" type area is in SRID units. For"geography" area is in square meters.• ST_AsBinary - Return the Well-Known Binary (WKB) representation of the geometry/geography without SRID meta data.• ST_AsGML - Return the geometry as a GML version 2 or 3 element.• ST_AsGeoJSON - Return the geometry as a GeoJSON element.• ST_AsKML - Return the geometry as a KML element. Several variants. Default version=2, default precision=15• ST_AsSVG - Returns a Geometry in SVG path data given a geometry or geography object.• ST_AsText - Return the Well-Known Text (WKT) representation of the geometry/geography without SRID metadata.• ST_Buffer - (T) For geometry: Returns a geometry that represents all points whose distance from this Geometry is less thanor equal to distance. Calculations are in the Spatial Reference System of this Geometry. For geography: Uses a planartransform wrapper. Introduced in 1.5 support for different end cap and mitre settings to control shape. buffer_style options:quad_segs=#,endcap=round|flat|square,join=round|mitre|bevel,mitre_limit=#.#• ST_CoveredBy - Returns 1 (TRUE) if no point in Geometry/Geography A is outside Geometry/Geography B• ST_Covers - Returns 1 (TRUE) if no point in Geometry B is outside Geometry A. For geography: if geography point B is notoutside Polygon Geography A• ST_DWithin - Returns true if the geometries are within the specified distance of one another. For geometry units are in thoseof spatial reference and For geography units are in meters and measurement is defaulted to use_spheroid=true (measure aroundspheroid), for faster check, use_spheroid=false to measure along sphere.