[postgis-users] Problem with functions contains

Martin Davis mbdavis at VividSolutions.com
Wed Oct 5 11:50:59 PDT 2005

>From my testing in JUMP & JTS, it is the case that the table2 geometry
(b) is completely contained in the table1 geometry (a).   I can see the
same thing as shown in the image, but that's correct - b is the blue
geometry, and it contains the red geometry (a).
To me it looks like PostGIS, JUMP and JTS are all saying the same thing,
and it matches the geometric situation.
Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046

	-----Original Message-----
	From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Miguel de la Fuente
	Sent: October 4, 2005 2:10 PM
	To: postgis-users at postgis.refractions.net
	Subject: [postgis-users] Problem with functions contains
	strk: I' have the following problem, when I use the function
contains it returns true when the polygons is not totally contains.
	I have applied snaptogrid in my geometry column.
	I did the following :
	update table1 set new_geom=snaptogrid(the_geom,1e-2)
	update table2 set new_geom=snaptogrid(the_geom,1e-2))
	When I use the function contains()
	from table2 b, table1 a
	where   contains (b.new_geom,a.new_geom)  
	it returns true,but I see visually that b not contains
completely a.
	I don't understand why??
	I attach the data and a image showing the problem.

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