[Gvsig_english] calculating centre points of polygon and ascribing coordinates

[Wolfgang Qual]

Hi Simon,
well, I browsed a little bit and found an answer:
you can export your polygon layer to an annotation layer (export to...
annotation). Then edit this annotation layer (add x- and y-coordinates
using the field calculator). 

best,
wolfgang
Am Mittwoch, den 25.11.2009, 00:20 +1100 schrieb Simon Cropper
(Botanicus Australia Pty Ltd):
> Hi,
> 
> I have found some answers.
> 
> First X, Y can be extracted with the field calculator using the 
> functions x() and y().
> 
> Sextante can be used to extract the centre point of a polygon.
> 
> This aside is there any way of consolidating these tasks? Can you 
> calculate the centre point of a polygon in gvSIG?
> 
> Cheers Simon
> 
> Simon Cropper
> Botanicus Australia Pty Ltd
> PO Box 160, Sunshine, Victoria 3020.
> P: 9311 5822. M: 041 830 3437.
> mailto: scropper at botanicusaustralia.com.au 
> <mailto:scropper at botanicusaustralia.com.au>
> web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>
> 
> 
> 
> Simon Cropper (Botanicus Australia Pty Ltd) wrote:
> > Hi Everyone,
> >
> > Can someone tell me if gvSIG can be used to establish the centre point 
> > of a polygon?
> >
> > ... and subsequently place the X and Y coordinates in fields in the 
> > attribute table of the polygon shapefile?
> >
> > ... or alternatively create a point file representing the centrepoint 
> > and be able to assign the XY values to that shapefile.
> >
> > What I regularly do in alternative programs (OpenJUMP, Kosmo, Sextante) 
> > is create a point file showing the centrepoint of a set of polygons 
> > (usually representing the sites I have surveyed) and then using ArcView 
> > assign the XY coordinate of the points to the northing+easting fields. 
> > Reproject into Lat-Long and repeat. These coordinates are used to report 
> > the sites locations to government agencies.
> >
> > How would you do this in gvSIG?
> >
> > Can you use Jpython to do this?
> >   
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