Finding a point inside a polygon

Mark Maunder · *nix forums beginner Joined: 20 Jul 2006 Posts: 3

I'd like to test whether a point is truly inside a polygon, not just
insude the minimum bounding rectangle. Is there a way to do this in
MySQL with the spatial extensions? I love mysql but I'm forced to
consider migrating to postgresql (ugh!) because it has built in
support for testing spatial relationships between polygons and points.

Thanks.

Mark.

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Mark Maunder · *nix forums beginner Joined: 20 Jul 2006 Posts: 3

Thanks, but according to the documentation the Contains() function is
the same as the MBRContains() function which only tests if the point
is inside the minimum bounding rectangle of the polygon, not the
actual polygon.

See the following:
http://dev.mysql.com/doc/refman/5.0/en/functions-that-test-spatial-relationships-between-geometries.html

From the manual:

"Currently, MySQL does not implement these functions according to the
specification. Those that are implemented return the same result as
the corresponding MBR-based functions."

On 7/21/06, ViSolve DB Team <mysql_support@visolve.com> wrote:

Visolve DB Team · *nix forums beginner Joined: 21 Jul 2006 Posts: 3

Hello Mark,

You can locate a point, whether inside or outside a polygon area using the
query below:

SELECT contains(geomfromtext(@poly),geomfromtext(@p));

where @poly,@p are variables.
Eg: set @p='Point(3 2)';
set @poly= 'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))
';

If the return value of the select statement is
0 -> Outside the polygon
1 -> Inside the polygon

Thanks,
ViSolve MySQL Support Team.
----- Original Message -----
From: "Mark Maunder" <mmaunder@gmail.com>
To: <mysql@lists.mysql.com>
Sent: Friday, July 21, 2006 4:40 AM
Subject: Finding a point inside a polygon

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