[postgis-users] Centroid Calculation Error???

[Martin Davis]

Can you submit the WKT for the feature?  I'm curious how JTS/GEOS handle this.

Martin Davis, Senior Technical Architect
Vivid Solutions Inc.
Suite #1A-2328 Government Street   Victoria, B.C.   V8T 5G5
Phone: (250) 385 6040 - Local 308      Fax: (250) 385 6046



> -----Original Message-----
> From: Düster Horst [mailto:Horst.Duester at bd.so.ch]
> Sent: Tuesday, October 28, 2003 6:18 AM
> To: postgis-users at postgis.refractions.net
> Subject: [postgis-users] Centroid Calculation Error???
> 
> 
> I try to calculate a centroid for a polygon with 
>  
> select centroid(wkb_geometry) from polygon_table;
>  
> You can see the result of the calculation in the attached 
> image. The red
> point is the place of the calculated centroid. This place is obviously
> wrong. I think the reason for this wrong placement is the 
> weight of the
> vertex points (yellow with black center). The centroid point 
> is shifted to
> the north east edge of the polygon due to the heavy 
> concentration of vertex
> points in this area of the polygon. In my opinion the 
> distribution of vertex
> points shouldn't have an influence of the centroid position.
>  
> Perhaps I'm wrong?? Any hints?
>  
> Horst
>