Polygons do not contain their holes. For a point P in a MultiPolygon M
which is inside a hole in one of the component Polygons you should have:
ST_within(P, M) = false
ST_contains(M, P) = false
Best to post your WKT and your query to confirm that's the problem.
Jorge wrote:
Hello,
I have a question. If a multipolygon has inner "holes", are these holes
part of the multipolygon? I mean, if I want to check if a given point is
inside of a multipolygon (using "within" or "contains") and this point
is in the hole, should "within" and "contains" return "true"?
Being more specific, I have a multypolygon that represents a forest, in
a map. This multipolygon has a hole inside. Then, I have another
multipolygon that fits exactly into the hole, and represents an airport.
If I select a point from the airport, this point is inside the second
multipolygon, of course, but should it be inside the first one too?
Because my problem is that I have to decide if the point is part of the
airport or part of the forest, and "within" and "contains" methods
return both multipolygon, instead of only the second one (the airport).
Maybe is more clear with an image:
http://www.nebulared.com/tmp_geo/multipolygon.jpg
Thanks in advance!
Regards
Jorge
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Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022
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