0

I am using QGIS.

Which projections / CRS are best to use for Switzerland and Germany, which I can use to buffer points and lines in metres rather than degrees?

PolyGeo
  • 65,136
  • 29
  • 109
  • 338
Shona Guthrie
  • 19
  • 4
  • @Taras Does that mean that this question should really be split into separate questions for Germany and Switzerland? – PolyGeo Oct 25 '21 at 05:44
  • I think this question should not be closed as a duplicate, rather as one that need more details. @PolyGeo, splitting into two questions IMHO does make that much sense, because maybe the OP wants to perform some calculations within these two countries. – Taras Oct 25 '21 at 05:47
  • @Taras If they're looking for a "mutual CRS for DACH" (Deutschland, Austria, Confoederatio Helvetica,) then perhaps they should edit their question to ask for that. Alternatively if they're looking for the "best" to use individually for each of Germany and Switzerland than I think two questions would be appropriate. Making a question into a duplicate can often lead to potential duplicates becoming disambiguated. – PolyGeo Oct 25 '21 at 06:03
  • 1
    Depends on where in Germany and/or Switzerland you "are". Depends on how detailled/correct calculations have to be. Depends on whether you're willing to work with different projects and CRS, or not. – Erik Oct 25 '21 at 07:02
  • 2
    Please do not ever use EPSG:3857 (Web Mercator) to carry out any sort of distance related analysis. The longitude (X) axis is distorted to infinity as you move north or south of the Equator. – Ian Turton Oct 25 '21 at 07:18
  • For Switzerland, use one of the official projections, the Swiss coordinate system (Swiss grid), see: https://en.wikipedia.org/wiki/Swiss_coordinate_system . See also: https://www.swisstopo.admin.ch/en/knowledge-facts/surveying-geodesy/reference-frames/local/lv95.html Have a look at EPSG:2056 = CH1903+ / LV95 (ellipsoid: Bessel 1841, local reference system) and EPSG:4932 = CHTRS95 (Swiss Terrestrial Reference System 1995, ellipsoid GRS80, thus compatible with European Terrestrial Reference System 1989). The older system still in use is EPSG:21781 = CH1903 / LV03 (ellipsoid: Bessel 1841) – Babel Oct 25 '21 at 07:23
  • @IanTurton, I absolutely agree with your statement, however, I do not understand the most correct approach in handling measurements (e.g. distances) that are not within the same country, e.g. measuring distance from London to Berlin? – Taras Oct 25 '21 at 07:34
  • ETRS89 is probably suitable for you needs if you want to use the same CRS for all three countries - EPSG:4258 – Babel Oct 25 '21 at 07:36
  • @Taras: using ellipsoidal measurements instead of planar ones is always a great way to calculate such distances - then even with EPSG:3857 returns good results. See especially https://gis.stackexchange.com/a/408399/88814, but also Two-point equidistant projection, see: https://gis.stackexchange.com/a/395766/88814 and https://gis.stackexchange.com/a/396041/88814 – Babel Oct 25 '21 at 07:47
  • Details on swiss coordinate system by Swisstopo, swiss federal office of Topography: https://www.swisstopo.admin.ch/content/swisstopo-internet/en/swisstopo/documents.download/swisstopo-internet/en/documents/geo-documents/SwissProjectionGIS-Version1-2.pdf – Babel Oct 25 '21 at 08:18

0 Answers0