[QGIS-Developer] [Qgis-user] New Features in Shape Tools 3.2.0

[Kristian Evers]

Hi Paolo,

I have some rought notes that I can try to polish up a bit and share here.
I'll see if I can find the time for that today. I didn't get to the bottom of
the problem but I am leaning towards the issue being that QGIS uses an
inferior algorithm to determine geodesics. Unfortunately I couldn't find out
from either the source code or the documentation which algorithm is used.
As far as I remember it differs from the otherwise popular algorithm by
Vincenty. That may be because a different algorithm is used or the
Implementation is wrong.

I'll get back with a better write-up later and some test data and results.

/Kristian

-----Oprindelig meddelelse-----
Fra: QGIS-Developer <qgis-developer-bounces at lists.osgeo.org> På vegne af Paolo Cavallini
Sendt: 25. september 2018 08:23
Til: qgis-developer at lists.osgeo.org
Emne: Re: [QGIS-Developer] [Qgis-user] New Features in Shape Tools 3.2.0

Hi Kristian,


Il 09/25/2018 07:24 AM, Kristian Evers ha scritto:
>
>
> On a related note, I have been meaning to raise a similar issue based
> on QGIS’s not so accurate polygon-area-on-the-ellipsoid calculations.
> A colleague of mine came across some differences between QGIS and
> CARIS LOTS while doing area calculations in relation to a border
> dispute at sea. After that I tested several popular closed source GIS
> apps and they all performed better than QGIS.
this is worth exploring in detail. could you please be more specific? do
you have a test case? could you share the results, or give us a way to
replicate them?
Thanks.

-- 
Paolo Cavallini - www.faunalia.eu
QGIS.ORG Chair:
http://planet.qgis.org/planet/user/28/tag/qgis%20board/

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