PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual234 / 3107.9.18 ST_SymDifferenceST_SymDifference — Returns a geometry that represents the portions of A and B that do not intersect. It is called a symmetricdifference because ST_SymDifference(A,B) = ST_SymDifference(B,A).Synopsisgeometry ST_SymDifference(geometry geomA, geometry geomB);DescriptionReturns a geometry that represents the portions of A and B that do not intersect. It is called a symmetric difference becauseST_SymDifference(A,B) = ST_SymDifference(B,A). One can think of this as ST_Union(geomA,geomB) - ST_Intersection(A,B).Performed by the GEOS moduleNoteDo not call with a GeometryCollection as an argumentThis 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: 5.1.21This function supports 3d and will not drop the z-index. However it seems to only consider x y when doing the differenceand tacks back on the Z-IndexExamplesThe original linestrings shown togetherThe symmetric difference of the two linestrings