[gdal-dev] Buffering geometries

[Even Rouault]

Le mardi 01 octobre 2013 22:05:55, Federico Jurio a écrit :
> Thank you for your advice Even, it works perfectly!
> i have another issue, what is the unit of dfDist from
> Buffer<http://www.gdal.org/ogr/classOGRGeometry.html#ab34b27e2c8812a0fc1dcc
> f055b11d1a2> ?

The same unit as the coordinates of your geometries : degrees if your 
coordinates are in degrees, meters if they are in meters, etc...

> 
> 
> On Tue, Oct 1, 2013 at 4:02 PM, Even Rouault
> 
> <even.rouault at mines-paris.org>wrote:
> > Le lundi 30 septembre 2013 23:12:30, federico a écrit :
> > > Dear all, i'm trying buffer some geometries with GDAL. I have success
> > 
> > with
> > 
> > > poligons and lines but i can't create the buffer when i try to do the
> > 
> > same
> > 
> > > procedure with an OGRPoint.
> > > 
> > > Here is a screenshot with the buffer http://i.imgur.com/rRQuooc.jpg
> > > 
> > > I'm using the Buffer function from OGRGeometry Class in a map with WGS
> > > 84 coordinates reference system.
> > > 
> > > Anyone know what could be wrong?
> > 
> > This should work. Make sure your target layer can contain polygons. Your
> > code
> > sample isn't sufficient to detect what might go wrong in your case.
> > 
> > Just a few remarks : you are going to suffer from 3 memory leaks in your
> > code
> > sample (if it isn't an extract of your real code) :
> > * Buffer() returns a new geometry object. So use SetGeometryDirectly() so
> > that
> > it is owned by pnewfeature
> > * you should delete pnewfeature after having passed it to CreateFeature()
> > * you should delete pfeature when it is no longer used
> > 
> > > Code example
> > > 
> > >    OGRFeature *pfeature = player->GetNextFeature(); // Apunta al primer
> > > 
> > > feature
> > > 
> > >    while (pfeature) {
> > >    
> > >       OGRFeature* pnewfeature = pfeature->Clone();
> > 
> > pnewfeature->SetGeometry(pnewfeature->GetGeometryRef()->Buffer(bufferdist
> > ))
> > 
> > > ; pdestlayer->CreateFeature(pnewfeature);
> > > 
> > >       pfeature = player->GetNextFeature();
> > >    
> > >    }
> > > 
> > > --
> > > View this message in context:
> > > http://osgeo-org.1560.x6.nabble.com/Buffering-geometries-tp5081031.html
> > > Sent from the GDAL - Dev mailing list archive at Nabble.com.
> > > _______________________________________________
> > > gdal-dev mailing list
> > > gdal-dev at lists.osgeo.org
> > > http://lists.osgeo.org/mailman/listinfo/gdal-dev
> > 
> > --
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> > http://even.rouault.free.fr/services.html

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