From: Regina Obe Date: Tue, 10 Nov 2009 12:13:45 +0000 (+0000) Subject: Put in ST_Intersection proto for geography X-Git-Tag: 1.5.0b1~267 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a6509bd80265b346628faca40466ea0ab153f6a2;p=postgis Put in ST_Intersection proto for geography git-svn-id: http://svn.osgeo.org/postgis/trunk@4772 b70326c6-7e19-0410-871a-916f4a2858ee --- diff --git a/doc/reference.xml b/doc/reference.xml index 1836ee950..cec6eace6 100644 --- a/doc/reference.xml +++ b/doc/reference.xml @@ -12220,7 +12220,7 @@ SELECT ST_Buffer(ST_GeomFromText('POINT(50 50)'), 20) As smallc, ST_Buffer - For geometry: Returns a geometry that represents all points whose distance + (T) For geometry: Returns a geometry that represents all points whose distance from this Geometry is less than or equal to distance. Calculations are in the Spatial Reference System of this Geometry. For geography: Uses a planar transform 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=#.# @@ -12267,7 +12267,7 @@ SELECT ST_Buffer(ST_GeomFromText('POINT(50 50)'), 20) As smallc, are in the Spatial Reference System of the geometry. Introduced in 1.5 support for different end cap and mitre settings to control shape. Geography: For geography this is really a thin wrapper around the geometry implementation. It first determines the best SRID that - fits the bounding box of the geography object (favoring UTM and falling back on mercator in worst case scenario) and then buffers in that planar spatial ref and retransforms back to WGS84 geography. + fits the bounding box of the geography object (favoring UTM, polar stereographic and falling back on mercator in worst case scenario) and then buffers in that planar spatial ref and retransforms back to WGS84 geography. For geography this may not behave as expected if object is sufficiently large that it falls between two UTM zones or crosses the dateline Availability: 1.5 - ST_Buffer was enhanced to support different endcaps and join types. These are useful for example to convert road linestrings @@ -13235,7 +13235,8 @@ SELECT ST_AsEWKT(geom) As the_geom, path ST_Intersection - Returns a geometry that represents the shared portion of geomA and geomB + (T) Returns a geometry that represents the shared portion of geomA and geomB. The geography implementation + does a transform to geometry to do the intersection and then transform back to WGS84. @@ -13251,6 +13252,17 @@ SELECT ST_AsEWKT(geom) As the_geom, path geomB + + geography ST_Intersection + + geography + geogA + + + geography + geogB + + @@ -13266,11 +13278,16 @@ SELECT ST_AsEWKT(geom) As the_geom, path ST_Intersection in conjunction with ST_Intersects is very useful for clipping geometries such as in bounding box, buffer, region queries where you only want to return that portion of a geometry that sits in a country or region of interest. + + Geography: For geography this is really a thin wrapper around the geometry implementation. It first determines the best SRID that + fits the bounding box of the geography object (favoring UTM, polar stereographic and falling back on mercator in worst case scenario) and then buffers in that planar spatial ref and retransforms back to WGS84 geography. Do not call with a GEOMETRYCOLLECTION as an argument Performed by the GEOS module + + Availability: 1.5 support for geography data type was introduced.