[GRASS-user] v.to.db area calculations

[James Duffy]

Hello,

Thanks for the reply. I don't have SAGA or PostGIS set up at the moment.
(have sent Stefan the shapefile off-list).

Moritz - I know that the QGIS value is true. The polygon has been drawn
over a feature on a raster image (which I know is correct in its
dimensions).

Thanks

James

On 19 May 2017 at 08:36, Moritz Lennert <mlennert at club.worldonline.be>
wrote:

> On 18/05/17 18:41, Blumentrath, Stefan wrote:
>
>> Hi James,
>>
>> QGIS uses a ellipsoidal area measurement, while GRASS (like most of the
>> other GIS) uses a Cartesian measurement (others, please correct me if that
>> is not the case in WGS84).
>>
>> See amongst others:
>> https://issues.qgis.org/issues/12057 and
>> https://issues.qgis.org/issues/14675
>>
>> Would you mind comparing area measurement of a third software (SAGA,
>> PostGIS, ...)?
>>
>
> I would suggest making tests with polygons of which you know the area
> (e.g. simple squares to begin with)
>
> Moritz
>



-- 
*James Duffy*
PhD Researcher
Environment and Sustainability Institute
Penryn Campus
University of Exeter
Penryn
Cornwall
TR10 9FE
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