[postgis-users] distance() for 3d points

[Rick Schumeyer]

Does the distance() function work for 3d points, or is there a distance3d()
function?

 

My quick tests show that distance() seems to use only the first two
dimensions and ignore the third:

 

select AddGeometryColumn('t2','geom',-1,'POINT', 3);

 

insert into t2 (name, geom) values ('p1',GeomFromEWKT('POINT(0 0 0)'));

insert into t2 (name, geom) values ('p2',GeomFromEWKT('POINT(0 0 1)'));

insert into t2 (name, geom) values ('p3',GeomFromEWKT('POINT(0 1 1)'));

insert into t2 (name, geom) values ('p4',GeomFromEWKT('POINT(1 1 1)'));

 

select distance( geom ,GeomFromEWKT('POINT(0 0 0)')) from t2;

 

    distance     

-----------------

               0

               0

               1

 1.4142135623731

 

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