[gdal-dev] Using -overwrite to create empty feature class

[Donovan Cameron]

I will definitely not recommend it then. Seems I got lucky in this case
scenario.

Thanks.



Donovan

On Fri, Feb 3, 2012 at 3:19 PM, Even Rouault
<even.rouault at mines-paris.org>wrote:

> Le vendredi 03 février 2012 22:59:36, Donovan Cameron a écrit :
> > FYI
> >
> > Further testing with -overwrite given your explanation
> > *ogr2ogr -overwrite output.shp output.shp -progress*
> > ...works as well but only if the files are in the same output directory
>
> Overwriting the source file with itself is definitely not supported. Do at
> your
> own risk ! The DBF error isn't surprising in that context.
>
> >
> > But it does report a dbf error:
> > *ERROR 1: fread(631) failed on DBF file.*
> >
> > But I can still open the output for appending and view the results in a
> GIS
> > viewer like QGIS.
> >
> > Though the -where or -fid trick works as well
> >
> > On Wed, Feb 1, 2012 at 2:38 PM, Even Rouault
> >
> > <even.rouault at mines-paris.org>wrote:
> > > Le mercredi 01 février 2012 22:22:42, Donovan Cameron a écrit :
> > > > Afternoon List.
> > > >
> > > > I am trying to generate an empty feature (shp or gml) from a template
> > >
> > > that
> > >
> > > > retains both the attribute-table schema and map projection.
> > > >
> > > > I can't get the *-overwrite *flag to work, it just copies the entire
> > > > feature (ie, makes a duplicate):
> > > > *ogr2ogr -overwrite -f "GML" geoname.gml /vsizip/vsicurl/
> > > > ${inZIP}/${inGML}* *
> > > > *
> > > > The next commands <http://gis.stackexchange.com/a/16510/1297>[1]
> work
> > >
> > > using
> > >
> > > > *-where *or *-fid*:
> > > > *ogr2ogr -f "GML" geoname.gml /vsizip/vsicurl/ ${inZIP}/${inGML}
> -where
> > > > "FID < 0"*
> > > > *ogr2ogr -f "GML" geoname.gml /vsizip/vsicurl/ ${inZIP}/${inGML} -fid
> > > > "< 0"*
> > > >
> > > > I thought the* -overwrite* flag would delete the output layer and
> > >
> > > recreate
> > >
> > > > it empty <http://www.gdal.org/ogr2ogr.html>[2]?
> > >
> > > -overwrite deletes the output layer, so that the new features added by
> > > ogr2ogr
> > > aren't added to the previously existing one, but in no way it creates
> an
> > > empty
> > > layer.
> > >
> > > The -where "fid < 0" trick is actually an interesting one. I've no
> better
> > > suggestion.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20120204/e5f10974/attachment.html