[postgis-users] Point in Polygon Problem

[Marc Jansen]

  Hi Paul,

AFAICT you are using ST_Cointains correctly, and MultiPolygons shouldn't 
be an issue. I assume that your geometries have the same SRID, otherwise 
PostGIS would complain.

Can you post a full example (including the WKT of both geometries) where 
you get false but expect true for ST_Contains(geomA, geomB)?

Something like:

SELECT ST_Contains('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))', 'POINT(5 
5)')  or
SELECT ST_Contains('MULTIPOLYGON(((0 0, 0 10, 10 10, 10 0, 0 0)))', 
'POINT(5 5)')

so everyone can easily test this.

Both yield true for my -- ancient ;-) -- POSTGIS="1.3.5" 
GEOS="3.0.3-CAPI-1.4.2" PROJ="Rel. 4.4.9, 29 Oct 2004" USE_STATS

Regards,
Marc




Am 22.10.2010 08:37, schrieb Marcos Paul:
> Hi Folks,
>
> I am trying to solve a simple problem: the point in polygon. First of 
> all, I have a CSV file with the polygons in list similar to the WKT 
> Format, that is something like:
>
> BUILT_UP_AREA_ID 	VERTEX_SEQ 	LATITUDE 	LONGITUDE
> 1081 	0 	152.6657 	-25.5206
> 1081 	1 	152.6662 	-25.5211
> 1081 	2 	152.6666 	-25.5216
> 1081 	3 	152.6673 	-25.5224
> 1081 	4 	152.668 	-25.523
> 1081 	5 	152.6694 	-25.5247
> 1081 	6 	152.67 	-25.5255
> 1081 	7 	152.6707 	-25.5263
> 1081 	8 	152.6734 	-25.5291
> 1081 	9 	152.6741 	-25.5295
> 1081 	10 	152.6745 	-25.5299
> 1081 	11 	152.675 	-25.5301
> 1081 	12 	152.676 	-25.5313
> 1081 	13 	152.6762 	-25.5317
> 1081 	14 	152.6764 	-25.5321
> 1081 	15 	152.6764 	-25.5333
> 1081 	16 	152.6766 	-25.534
> 1081 	17 	152.6766 	-25.5341
> 1081 	18 	152.6771 	-25.5341
> 1081 	19 	152.6774 	-25.534
> 1081 	20 	152.6788 	-25.5354
> 1081 	21 	152.6797 	-25.5361
> 1081 	22 	152.6788 	-25.5368
>
>
>
> From there I want to export that to my postgis data base, I solved 
> that converting the CSV to a Shape file and then applying the shp2psql 
> gui.
>
> When I am trying to check if a particular point is inside my table I 
> am just applying the following command:
>
> select ST_ASTEXT(the_geom) as multipolygons FROM Table_Polygons WHERE 
> ST_Contains(Table_Polygons.the_geom, ST_GeometryFromText('POINT(X,Y)'));
>
> So after that, I am getting that the point X,Y is not inside one of 
> the polygons of my file, when I am completely sure that this point is 
> actually inside a polygon.
>
> What I am doing wrong?  Does the fact that I am using Multipolygons 
> affect at all?
>
> Thank you for your help,
>
> Paul
>
>
>
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