[Qgis-user] results Measure Tool vs. length()

[Michel Stuyts]

$length gives the same result as length($geometry)


Michel

Van: Springfield Harrison [mailto:stellargps at gmail.com]
Verzonden: vrijdag 18 mei 2018 2:52
Aan: Michel Stuyts <michel.stuyts at edegem.be>
CC: qgis-user <qgis-user at lists.osgeo.org>
Onderwerp: Re: [Qgis-user] results Measure Tool vs. length()


Interesting and alarming observation.

And how do those results compare with output from the $length variable?

Cheers . . . . .   Springfield
Samsung Tab 4
On May 17, 2018 5:26 AM, "Michel Stuyts" <michel.stuyts at edegem.be<mailto:michel.stuyts at edegem.be>> wrote:
In the length() function QGIS uses the CRS unit of the layer to calculate the result. When I use for example a layer in a local CRS like EPSG:31370 or EPSG:5439 and a layer in EPSG:3857 (that all use meters as unit) the results are very different (+40% difference). Changing the project CRS makes no difference. When I check the length using the Measure Tool the results are very similar to the local CRS.

How can I measure the length of a line and use it as a label independent from the layer CRS and get results similar to the results of the Measure Tool?

Michel

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