Line/Area Ruler: algorithm for measuring

[arimonma]

Line/Area Ruler The algorithm for measuring needs improvement and should mention the different scale in north-south and west-east extension, depending on chosen projection.

Example for Germany:

North end of Sylt Island (WGS84: x=8.41 y=55.06) to south end of Königsee Lake (WGS84: x=12.97 y=47.52) EPSG:25832, EPSG:31467 ~ 900 km (what is OK) EPSG:4326 ~ 980 km (what is acceptable)

West / Aachen (WGS84: x=6.05 y=50.78) to East / Görlitz (WGS84: x=14.97 y=51.16) EPSG:25832, EPSG:31467 ~ 625 km (what is OK) EPSG:4326 ~ 990 km (what is NOT OK)

QGis for example calculates correct distances.

[AxxL]

Think this is related to the inability to measure correct values with WGS84. We'll see what we can do - for example to project to a different system for measuring.

[arimonma]

Hi Axel, couldn’t you try to find out how QGIS does this? There it works correctly, even with EPSG:4326. Also have a look at https://www.kompf.de/gps/distcalc.html. It should be possible with PROJ.4 (I guess Mapbender3 uses it, too). Cheers, Martin

Von: Axel Schaefer [mailto:notifications@github.com] Gesendet: Freitag, 1. Juli 2016 14:11 An: mapbender/mapbender mapbender@noreply.github.com Cc: Arimont, Martin Martin.Arimont@ble.de; Author author@noreply.github.com Betreff: Re: [mapbender/mapbender] Line/Area Ruler: algorithm for measuring (#417)

Think this is related to the inability to measure correct values with WGS84. We'll see what we can do - for example to project to a different system for measuring.

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[AxxL]

Okey, wir schauen uns das an.

[AxxL]

https://github.com/mapbender/mapbender/tree/hotfix/measure-add-geodesic

Will be part of the next bugfix release.