On Fri, 19 Jul 2019 at 00:38, Andreas Neumann <[email protected]> wrote: > > Hi, > > We are having issues on the QGIS 3.4 release that the difference between and > ellipsoidical and planimetric distance (and area) is huge. Too huge. > > We have this issue on Windows 3.4.9, but on Linux (a bit newer commit) I > don't have the same huge difference, but rather a very reasonable one. > > I noticed that while the Windows version was built with proj 520 and the > Linux version with 493, so a bit older. > > But I don't know if the measurement tool in QGIS is using proj at all or not? > If yes, could it be that newer proj releases made things worse regarding > ellipsoidical measurements?
It's possible. The actual measurement calculation uses code ported from GRASS (and not the proj implementation of these algorithms), but proj IS used in transforming map/measure coordinates prior to calculating the distance. Possibly something has changed there which is impacting this. Could you please test: 1. Do you see the same distance values when measuring feature lengths? I.e. setup a layer with a feature with the same line as you are measuring, and check the identify tool derived attributes or $length value for it. 2. Can you confirm that the project ellipsoid settings are identical between the windows & linux builds? 3. Can you share an example I can test with? Nyall _______________________________________________ QGIS-Developer mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
