[teiid-issues] [JBoss JIRA] (TEIID-4580) ST_PointOnSurface returns point on the boundary of the polygon

[Andrej Šmigala (JIRA)]

Andrej Šmigala created TEIID-4580:
-------------------------------------

             Summary: ST_PointOnSurface returns point on the boundary of the polygon
                 Key: TEIID-4580
                 URL: https://issues.jboss.org/browse/TEIID-4580
             Project: Teiid
          Issue Type: Bug
    Affects Versions: 9.x, 8.12.7.6_3
            Reporter: Andrej Šmigala
            Assignee: Steven Hawkins


Calling ST_PointOnSurface with a polygon argument returns one of the points of the polygon boundary. 

E.g.
{code:sql}
SELECT ST_AsText(ST_PointOnSurface(ST_GeomFromText('POLYGON ((67 13, 67 18, 59 18, 59 13, 67 13))')));
{code}
returns {{POINT (67 13)}}

The spec says
bq. PointOnSurface( ):Point—A point guaranteed to be on this Surface.

which might not be completely clear, but [several|http://gis.stackexchange.com/questions/76498/how-is-st-pointonsurface-calculated] [sources|http://workshops.boundlessgeo.com/postgis-intro/geometry_returning.html] indicate that "on this surface" means _inside_ the surface.

When running the same query against a postgis instance (not through teiid), the result is {{POINT(63 15.5)}}, which is actually inside the polygon.



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