[postgis-users] Point in Polygon Problem

[pcreso at pcreso.com]

Paul

I suggest you chaeck the XY coords in your data, it looks like you have mislabeled lat & lon, your "lat" values are > 90 & <180.

If you have loaded these into Postgis with the coords reversed, then they will not be in the correct location, which could be why ST_contains fails

Brent Wood

--- On Sat, 10/23/10, Marc Jansen <jansen at terrestris.de> wrote:

From: Marc Jansen <jansen at terrestris.de>
Subject: Re: [postgis-users] Point in Polygon Problem
To: postgis-users at postgis.refractions.net
Date: Saturday, October 23, 2010, 8:50 AM



  

    
  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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