On 20 Oct 2015 9:36 PM, "Giovanni Manghi" <[email protected]> wrote: > > > The thing is, I'm not convinced the area is wrong... it's just that > > QGIS' handling of units with OTF on/off ellipsoid ON/OFF is extremely > > confusing (ie, I don't even fully understand it). > > My understanding, at least until http://hub.qgis.org/issues/12057 , is > that the confusing bit is that sometimes areas measured on an > ellipsoid are smaller than the same ones measured on a plane, this > because not all projections are conservative for areas. Differences > are relatively small, of course if the area measured with OTF on > differs of several magnitudes then there is probably something wrong > (but do not seems the case anymore).
Yep, but that's expected/correct behaviour. Ellipsoidal area WILL differ from planar area and will differ between ellipsoids. So no issue there. > > There is also the issue with measurements being always in m for > projections in feet, this I can confirm after testing quickly (on > master) the dataset of http://hub.qgis.org/issues/13209 (but > transforming the result from square meters to acres give the right > results). Right, so that's more of a feature request/ui clarification. We need a way of notifying users what units the area will be in and also allow them to override this. I think removing the broken canvas units from project properties is a start, and maybe switching that to a selector for areal/distance unit calculations. Can't be solved for 2.12 though. Nyall > > cheers! > > -- G --
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