[Qgis-user] Measurement tool

[Nyall Dawson]

On Sat, 3 Nov 2018 at 01:54, Martin Weis <martin.weis.newsadress at gmx.de> wrote:
>
> Am 02.11.18 um 13:36 schrieb Josh Hull:
> > inaccurate measurement when I am measuring both area and straight line
>
> > and its using WGS 84 / Pseudo-Mercator. I primarily use the software for
> > maps in north central United States.
>
> Pseudo-mercator might be your issue here, it might have large
> distortions, since your region is far away from equator.
> Consider using UTM for metric units and measurements.

I suspect this is the issue - psuedo mercator is totally unsuitable
for any distance/area measurements.

Try using QGIS 3.4.1 and comparing the area/distances using the
identify tool on features. This will report both an ellipsoidal based
area/distance calculation and direct cartesian calculation (using
psuedo mercator in your case). You'll see huge discrepancies between
the values.

The real solution is to use an appropriate, well selected local
projection, which is deemed suitable for distance and area
measurements within your area of interest. Finding out what projection
this is is left as an exercise for the reader ;)

Nyall

>
> And have a look for the CRS of your project,according to:
> https://docs.qgis.org/2.8/en/docs/user_manual/introduction/general_tools.html#measuring
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