AW: [postgis-users] Centroid Calculation Error???

[Düster Horst]

Martin

Here the WKT of the polygon (Swiss Coordinates)


SRID=-1;POLYGON((594029.238 227076.667,594066.353 226989.68,594127.292
227001.806,594210.769 227017.778,594218.472 227018.871,594224.075
227019.225,594328.615 227028.385,594331.241 227028.382,594333.724
227027.428,594336.024 227026.092,594346.999 227019.388,594348.032
227020.432,594350.97 227023.404,594356.685 227031.13,594362.592
227040.194,594366.079 227045.735,594370.242 227053.048,594373.478
227060.511,594376.985 227068.785,594382.289 227079.941,594382.488
227080.884,594382.962 227087.377,594384.064 227093.667,594385.213
227096.506,594387.354 227100.144,594389.542 227101.84,594391.487
227102.947,594393.32 227104.067,594394.477 227104.395,594397.771
227090.279,594396.953 227091.474,594395.743 227091.446,594394.556
227090.976,594393.277 227089.864,594391.045 227085.427,594384.128
227069.284,594378.54 227057.05,594376.497 227052.679,594373.552
227046.879,594368.451 227038.839,594362.221 227029.185,594356.649
227021.43,594350.262 227013.202,594317.432 226980.488,594257.534
226946.253,594070.893 226878.908,593881.138 226809.861,593622.716
226735.129,593566.768 226904.993,593642.974 226925.582,593723.166
226942.676,593749.26 226939.353,593782.779 226940.175,593829.131
226935.872,594029.238 227076.667))

Horst

-----Ursprüngliche Nachricht-----
Von: Martin Davis [mailto:mbdavis at VividSolutions.com]
Gesendet am: Dienstag, 28. Oktober 2003 18:11
An: PostGIS Users Discussion
Betreff: RE: [postgis-users] Centroid Calculation Error???

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
> 

_______________________________________________
postgis-users mailing list
postgis-users at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users