Hi Nyall I'm afraid that 2.16 has still this issue. I've loaded an UTM-17 south layer (my zone) and a Lat-long layer and:
1. SRC was seted in UTM 2. In UTM layer, if OTF SRC transformation is active, I get different area than if it's deactivated. Correct value is the last one. 3. In Lat-long layer, if OTF SRC transformation is active, calculated area is same as the wrong value of first layer. I can't get the correct value in this layer, so I have to reproject into a new one and do step 2 (with OTF deactivated). What about a general option to set the prefered SRC to calculate areas and lengths with OTF active? Regards from Peru Carlos 2016-10-12 18:06 GMT-05:00 Nyall Dawson <[email protected]>: > On 12 Oct 2016 11:56 PM, "Carlos Cerdán" <[email protected]> wrote: > > > > AFAIK, It also is needed to turn off "on the fly SRC transformation" to > get correct area values.... Or QGIS has fixed this point? > > Everything should be fixed in recent versions, and I very (VERY) much want > to know if any issues are still encountered. > > Calculating area/length is a core task for a GIS and we need to make sure > it's rock solid. (Which it should be since 2.16!) > > Nyall > > > > > > If you can't get correct area values, check out about it.... > > > > > > 2016-10-12 7:40 GMT-05:00 DelazJ <[email protected]>: > >> > >> Hi, > >> To complete Nicolas answer, you should check what are the measurements > options set in Project --> Project Properties --> General tab. > >> See also http://docs.qgis.org/2.14/en/docs/user_manual/introduction/g > eneral_tools.html#measuring > >> > >> 2016-10-12 14:07 GMT+02:00 Nicolas Cadieux < > [email protected]>: > >>> > >>> Hi, > >>> You may be calculating square degrees and not metres. It can depend > on the crs depending on the tools you are using. > >>> Nicolas > >>> > >>> Le 11 oct. 2016 à 08:54, Martina Schäfer [via OSGeo.org] <[hidden > email]> a écrit : > >>> > >>>> I experienced some confusion with calculation of area using the field > calculator in QGIS version 2.16.3. Since I'm using MapInfo Professional as > well, I mainly use tab-files that I can open in both programmes, but > occasionally I save as shapefile since this used to be the default in QGIS. > >>>> > >>>> When comparing files, I coincidently realized that there was a > mismatch in calculated area for the shapefile and the tab-file for exactly > the same polygons! I used the field calculator in the attribute table in > both cases, but for the shapefile the resulting areas were almost doubled > in area compared to the tab-file. Any idea why this is happening? > >>>> > >>>> I also realized similar differences when calculating area in a file > where projection has been converted from SWEREF99TM (a Swedish national > projection) to WGS84. There differences occurred in both the tab and > shapefile compared to the area calculated for the same tab-file in MapInfo. > Again I find this very confusing! > >>>> > >>>> I need to rely on the area-calculations thus I really hope someone > here can explain to me what is happening! > >>>> > >>>> Thanks in advance, > >>>> Martina > >>>> > >>>> > >>>> > >>>> > >>>> ________________________________ > >>>> If you reply to this email, your message will be added to the > discussion below: > >>>> http://osgeo-org.1560.x6.nabble.com/inconsistenty-when-calcu > lating-area-depending-on-file-type-or-projection-tp5290228.html > >>>> To start a new topic under Quantum GIS - User, email [hidden email] > >>>> To unsubscribe from Quantum GIS - User, click here. > >>>> NAML > >>> > >>> > >>> ________________________________ > >>> View this message in context: Re: inconsistenty when calculating area > depending on file type or projection? > >>> Sent from the Quantum GIS - User mailing list archive at Nabble.com. > >>> > >>> _______________________________________________ > >>> Qgis-user mailing list > >>> [email protected] > >>> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > >>> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user > >> > >> > >> > >> _______________________________________________ > >> Qgis-user mailing list > >> [email protected] > >> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > >> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user > > > > > > > > _______________________________________________ > > Qgis-user mailing list > > [email protected] > > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user >
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