[gdal-dev] New OGR_GEOM_AREA special field

[Daniel Morissette]

No comments? I'll go ahead and commit support for the new OGR_GEOM_AREA 
special field to trunk tomorrow then...

Daniel


Daniel Morissette wrote:
> Hi GDAL Dev's,
> 
> I'd like to use a OGR SQL statement to filter features from a shapefile 
> based on their area. e.g. keep only the large lakes in a water layer for 
> instance.
> 
> A simple way to allow this would be to add a new OGR_GEOM_AREA special 
> field on OGRFeatures that calls the OGRSurface::getArea() method and 
> would be handled similar to the OGR_GEOM_WKT and other special fields in 
> OGRFeature::GetFieldAsString?().
> 
> Another option could be to add operators on geometries in the SQL parser 
> but that could be a bit more involved (e.g. "select ST_Area(geom) from 
> ...").
> 
> I have created a ticket about this which includes a patch for the new 
> OGR_GEOM_AREA special field:
> 
> http://trac.osgeo.org/gdal/ticket/2949
> 
> What would you think of adding this to the SVN trunk? Or can anyone 
> provide hints on the way to implement operators on geometries since that 
> would clearly be a better solution but I'm not clear on the best way to 
> add this to the OGR SQL engine.
> 
> Daniel


-- 
Daniel Morissette
http://www.mapgears.com/