[postgis-users] Roeck test

[Lee Meilleur]

Yes and yes to both questions, but the Roeck test is required by some states.  And some states don't allow their politicians to draw their political boundaries.

Thanks Martin, I'll test the convex hull and compare with the Roeck from our commercial software.

Brent, thanks for the link, not sure if Paul will get the algorithm into the final release of PostGIS 1.3.4.  I have two years to figure this out.


-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Martin Davis
Sent: Friday, October 24, 2008 11:40 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Roeck test


Wouldn't it be easier and more accurate to use the convex hull of the polygon instead of the minimum enclosing ball? The CH will have smaller area (i.e. be a tighter bound on the area covered by the polygon), so it seems like it would give a more accurate basis for comparison.

Lee Meilleur wrote:
> Has anyone calculated the Roeck test using PostGIS?  This is an area
> based measure that computes the ratio of the area of a polygon to the
> area of the minimum enclosing circle for the polygon.  It's used to
> measure compactness of districts for redistricting applications,
> basically a way to test for gerrymandering.  Thanks.
>
> Lee Meilleur
> LCC-GIS Office
> Minnesota Legislature
> 100 Rev. Dr. MLK Jr Blvd.
> 55 State Office Building
> St. Paul, MN 55155
> 651.296.0098  Fax: 651.297.3697
> lee.meilleur at gis.leg.mn
> http://www.gis.leg.mn
>
>
> _______________________________________________
> postgis-users mailing list postgis-users at postgis.refractions.net
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>
>

--
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022

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