PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual255 / 310NoteSince ST_Extent3D returns a bounding box, the SRID meta-data is lost. Use ST_SetSRID to force it back into ageometry with SRID meta data. The coordinates are in the units of the spatial ref of the orginal geometries.This function supports 3d and will not drop the z-index.This method supports Circular Strings and CurvesExamplesSELECT ST_Extent3D(foo.the_geom) As b3extentFROM (SELECT ST_MakePoint(x,y,z) As the_geomFROM generate_series(1,3) As xCROSS JOIN generate_series(1,2) As yCROSS JOIN generate_series(0,2) As Z) As foo;b3extent--------------------BOX3D(1 1 0,3 2 2)--Get the extent of various elevated circular stringsSELECT ST_Extent3D(foo.the_geom) As b3extentFROM (SELECT ST_Translate(ST_Force_3DZ(ST_LineToCurve(ST_Buffer(ST_MakePoint(x,y),1))),0,0, ←↪z) As the_geomFROM generate_series(1,3) As xCROSS JOIN generate_series(1,2) As yCROSS JOIN generate_series(0,2) As Z) As foo;b3extent--------------------BOX3D(1 0 0,4 2 2)See AlsoST_Extent, ST_Force_3DZ7.12.8 Find_SRIDFind_SRID — The syntax is find_srid(, , ) and the function returns the integer SRID of thespecified column by searching through the GEOMETRY_COLUMNS table.Synopsisinteger Find_SRID(varchar a_schema_name, varchar a_table_name, varchar a_geomfield_name);DescriptionThe syntax is find_srid(, , ) and the function returns the integer SRID of the specified column bysearching through the GEOMETRY_COLUMNS table. If the geometry column has not been properly added with the AddGeometryColumns()function, this function will not work either.