[gdal-dev] Reg: Getting center coordinates for the attributes in a geojson

[Even Rouault]

Le mercredi 18 février 2015 12:02:23, Manikanta Kondeti a écrit :
> Hello,
> 
> Thanks for the response.  Can I put a flag for the centroid computation?
> 
> For eg:  ogr2ogr -f GeoJSON -t_srs crs:84 [name].geojson [name].shp
>  (--flag for centroid??)

If your GDAL build is configured with spatialite support (and is at least GDAL 
1.10), you can try the ST_Centroid() SQL function with the SQLite dialect ( 
http://www.gdal.org/ogr_sql_sqlite.html )

Something like :

ogr2ogr -f geojson out.json poly.shp \
 -sql "select st_centroid(geometry) as geometry, * from poly" -dialect sqlite

> 
> 
> On Wed, Feb 18, 2015 at 4:20 PM, Even Rouault <even.rouault at spatialys.com>
> 
> wrote:
> > Le mercredi 18 février 2015 11:43:10, Manikanta Kondeti a écrit :
> > > Hi all,
> > > 
> > > I'm working on a project which aims  to visualize Spatial Vector Data
> > > on
> > 
> > a
> > 
> > > browser. Using gdal I will convert Shapefiles, kml, gml into geojson
> > > and send it back to the browser.
> > > 
> > > I want to draw labels(attributes) on the map, using GDAL can I get each
> > > feature's centre coordinates without computing them on the browser
> > > side,
> > 
> > so
> > 
> > > that I can easily draw them  on the map?
> > 
> > Mani,
> > 
> > OGR_G_Centroid() /  OGRGeometry::Centroid() should help.
> > 
> > See
> > http://www.gdal.org/ogr__api_8h.html#a23f5a19a81628af7f9cc59a37378cb2b
> > 
> > Even
> > 
> > --
> > Spatialys - Geospatial professional services
> > http://www.spatialys.com

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