[postgis-users] Reference Grid

[Bob Pawley]

Hi Regina

Thanks for the help.

I don't understand " INNER JOIN reference As r ON".

I get the error - > relation "reference" does not exist.

It doesn't like my substitution for reference either.

Bob

Bob
  ----- Original Message ----- 
  From: Paragon Corporation 
  To: 'PostGIS Users Discussion' 
  Sent: Sunday, April 19, 2009 8:58 PM
  Subject: RE: [postgis-users] Reference Grid


  Bob,

  Does the below help any.  The below will give you the centroid of the portion of geometries that intersect a reference grid where the grid of the reference is defined by reference.the_geom

  SELECT r.gid, r.the_geom, ST_Centroid(ST_Collect(ST_Intersection(r.the_geom,p.the_geom))) As the_centroid
  FROM tblpolygons As p INNER JOIN reference As r ON ST_Intersects(p.the_geom, r.the_geom)
  GROUP BY r.gid, r.the_geom


  Hope that helps,
  Regina



------------------------------------------------------------------------------
  From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Bob Pawley
  Sent: Sunday, April 19, 2009 1:58 PM
  To: PostGIS Users Discussion
  Subject: [postgis-users] Reference Grid


  Hi

  I'm using a reference grid of small polygons.

  I have been trying to collect concurrent polygons into one geometry in order to establish the centroid of the region covered. I've tried a number of operations such as union, contains, accum etc.

  I haven't been successful.

  Can anyone give me some ideas??

  Bob





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