PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual210 / 310Units of radius are measured in units of the spatial reference system.The inputs can be POINTS, MULTIPOINTS, LINESTRINGS, MULTILINESTRINGS, POLYGONS, MULTIPOLYGONS, andGeometryCollections.NoteThis function ignores the third dimension (z) and will always give a 2-d buffer even when presented with a 3d-geometry.Performed by the GEOS module.This method implements the OpenGIS Simple Features Implementation Specification for SQL 1.1. s2.1.1.3This method implements the SQL/MM specification. SQL-MM 3: 5.1.17NotePeople often make the mistake of using this function to try to do radius searches. Creating a buffer to to a radius searchis slow and pointless. Use ST_DWithin instead.Examplesquad_segs=8 (default)SELECT ST_Buffer(ST_GeomFromText(’POINT(100 90)’),50, ’quad_segs=8’);quad_segs=2 (lame)SELECT ST_Buffer(ST_GeomFromText(’POINT(100 90)’),50, ’quad_segs=2’);