[Qgis-user] How Do I Set Field Calculator Units For Area

Alister Hood alister.hood at synergine.com
Thu Sep 1 15:51:53 PDT 2011


Oh,
I should also mention that if I copy a feature to another layer which uses a different CRS but the same units, then the field calculator returns a _slightly_ different area (e.g. NZGD2000 vs NZGD49).

> -----Original Message-----
> From: Alister Hood
> Sent: Friday, 2 September 2011 10:28 a.m.
> To: 'giovanni.manghi at gmail.com'
> Cc: qgis-user at lists.osgeo.org
> Subject: RE: [Qgis-user] How Do I Set Field Calculator Units For Area
> 
> Hi Giovanni,
> Either you are mistaken, or there is a bug.  I have OTFR enabled, and the field
> calculator returns the same area when I set the project CRS to EPSG:32074
> (which uses feet), as it does when I set the project CRS to any normal CRS
> which uses metres.
> 
> Alister
> 
> > -----Original Message-----
> > From: Giovanni Manghi [mailto:giovanni.manghi at gmail.com]
> > Sent: Thursday, 1 September 2011 7:58 p.m.
> > To: Alister Hood
> > Cc: qgis-user at lists.osgeo.org
> > Subject: RE: [Qgis-user] How Do I Set Field Calculator Units For Area
> >
> > Calculations are in the project CRS unit if OTFR is enabled, if not, the
> > layer CRS unit is set in the general tab of the project properties.
> >
> > cheers
> >
> > -- Giovanni --
> >
> > On Thu, 2011-09-01 at 11:18 +1200, Alister Hood wrote:
> > > Hi there,
> > > I *think* the area calculations are always in the unit for the layer's
> > > CRS.  So you could either:
> > > - find out what this unit is, and convert the areas to square feet by
> > > multiplying by the correct factor, or
> > > - convert the layer to a CRS which uses square feet.
> > > N.B. there is a feature request to enable coordinate conversion in the
> > > field calculator (although I didn't mention that it would be useful also
> > > for area and length calculations).  See http://hub.qgis.org/issues/4078
> > >
> > > Alister
> > >
> > > > Date: Wed, 31 Aug 2011 11:18:32 -0500
> > > > From: Andrew Novak <novak.andj at gmail.com>
> > > > Subject: [Qgis-user] How Do I Set Field Calculator Units For Area
> > > > 	Calcs?
> > > > To: qgis-user at lists.osgeo.org
> > > > Message-ID:
> > > >
> > > <CAO0Lqnon=aJMKGUb=BPacqxgn+PGn4G2vpe8sn=epxyT+pKtbw at mail.gmail.com>
> > > > Content-Type: text/plain; charset="iso-8859-1"
> > > >
> > > > The area calculations from my field calculator are in an unknown unit.
> > > I
> > > > simply want my units to be square feet. How can I set my units in the
> > > field
> > > > calculator??
> > > _______________________________________________
> > > Qgis-user mailing list
> > > Qgis-user at lists.osgeo.org
> > > http://lists.osgeo.org/mailman/listinfo/qgis-user
> >



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