[postgis-users] contains function with complex polygons

Gilbert, Antoine AGilbert at korem.com
Thu Sep 28 08:51:36 PDT 2006


I was posting my problem in the JTS forum too because when I realized I
was wrong in my PostGIS application I figured I was too in an old one
using JTS stuff! So I had to verify both.

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Markus Schaber
Sent: September 28, 2006 10:55 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] contains function with complex polygons

Hi, Antoine,

Gilbert, Antoine wrote:

> I was used to the object model of another software I'm using who is
> ogc compliant.

You're not the only one who got caught by this trap.

Differing geometry models are one of the ugliest problems in the GIS
area. Some problems are:

- Polygon vs. MultiPolygon and islands

- (Counter)Clockwiseness of rings

- Repeating the first vertex of a ring as last one

- Are duplicated vertices allowed

- Which kind of "degenerated" geometries are allowed
  (1-point lines, 2-point polygons, polygons with area of 0)



Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in Europe! www.ffii.org
postgis-users mailing list
postgis-users at postgis.refractions.net

More information about the postgis-users mailing list