[postgis-users] [Question] Point returned in ST_LineLocatePoint and ST_ClosestPoint is not able to detect in ST_Contains

Dharshan Bharathur dharshan4help at gmail.com
Tue Sep 29 21:59:00 PDT 2015

Hi all, Need experts advice.

This is the same question I have asked here.

I am using postgis's ST_LineLocatePoint to find out the closest point on a
LineString to the given Point, and using  ST_LineInterpolatePoint to
extract a Point from the returned float number.(as referred here

This is my ST_LineLocatePoint Query

SELECT ST_AsText(ST_LineInterpolatePoint(foo.the_line,
         77.584841)')))) AS g FROM (SELECT ST_GeomFromText('LINESTRING(12.96145
         77.58408,12.96219 77.58447,12.96302 77.58489,12.96316
         77.58511)') AS the_line) AS foo;


 POINT(12.9624389808159 77.5845959902924)

Which exactly lies on the linestring I have passed. Demonstration is
displayed here <http://jsfiddle.net/2p3zekae/2/>.

query with St_Closest function also returns the same points.

But when I check whether this point lies in the same linestring using
ST_Contains it always return false, even though the point lies within.

My ST_Contains Query:
SELECT ST_Contains(ST_GeomFromText('LINESTRING(12.96145 77.58408,12.96219
77.58447,12.96302 77.58489, 12.96316 77.58496, 12.96348 77.58511)'),
ST_GeomFromText('POINT(12.9624389808159 77.5845959902924)'));


I am not getting where I am doing wrong, why I am getting false. Can anyone
help me in this.

I am using Postgresql : 9.4, postgis : 2.1

*Thanks & RegardsDharshan*
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