[postgis-users] filing the holes in the swiss cheese?

[Burgholzer,Robert]

I am trying to do a query of cities that are contained by counties (in
Virginia, US), so that I can have a list that cross-references by FIPS
these relationships.

 

My query looks like this:

 

select b.poli1 as fips, b.name, a.poli1 as contained_by_fips, a.name

from poli_bounds as a , poli_bounds as b 

where a.poli1 <> b.poli1 and a.the_geom && b.the_geom 

and contains(convexhull(a.the_geom), b.the_geom) 

and a.projectid = 1 

and b.projectid = 1;

 

 

This works fairly well, but omits a handful of cities that are most
definitely within the boundaries of the county. 

 

Is "convexhull()" the correct function for this?  Are my geometries
goofed up?

 

Thanks!

 

Robert W. Burgholzer

Surface Water Modeler

Office of Water Supply and Planning

Virginia Department of Environmental Quality

rwburgholzer at deq.virginia.gov

804-698-4405

Open Source Modeling Tools:

http://sourceforge.net/projects/npsource/

 

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