Check if point is inside unclosed linestring using POSTGIS ST Functions

Question

I have a table with spatial data. This table contains a single record which is a unclosed linestring.

I calculated the Centroid of this geometry using query

SELECT ST_AsText(ST_Centroid("geom")) FROM "public"."ha_ground"

I got the output "POINT(73.8180699704927 18.6281375643436)"

My aim is to check if this point is inside the unclosed linestring

I used the following query

SELECT ST_Contains("geom",ST_GeomFromText('POINT(73.8180699704927 18.6281375643436)', 4326)) FROM "public"."ha_ground"

As We know Centroid of this geometry is inside the unclosed linestring. But, This query returns false instead of true.

What is the possible reason for this.

And what is the solution to check if point is inside unclosed linestring

Answer 1

I believe this is what you have: a line and a disjoint point

First step you must do is to close the linestring but it is still a linestring and point is disjoint. All points which are not on the line are disjoint.

You must go on and convert the linearring into a polygon. Polygon does have a two-dimensional interior (area).

And only then you can get an answer to the question "Does a point locate inside a polygon which outer ring is is created by closing a linestring so that its end point is connected to its start point.