I'm using QGIS 3.4.1 on Windows. I am trying to use a point vector source from a public authority with OpenStreetMap data, but the points do not align with their expected locations.
Try the following:
- Create a new project.
- From the browser, go to the XYZ Tileserver category and add the OpenStreetMap layer to the project.
- Zoom in to Berlin, Germany.
- In the browser, right-click on WFS and choose "New connection..."
- Enter https://fbinter.stadt-berlin.de/fb/wfs/data/senstadt/s_messpunkte in the URL field, name the layer "emissions" (these are air quality testing stations) and click "OK".
- Add the layer from the provider to the project (Entwicklung Luftqualität - Immissionen (Umweltatlas))
The default CRS is EPSG:4326, the OSM "CRS" is EPSG:3857 and the CRS of the point layer with the air quality testing stations is EPSG:25833. (After adding the OSM data, the project's projection changes to EPSG:3857, as expected.)
The emissions layer seems to be displaced. Consider the point (1493533,6893411) in the emissions layer (the top point in the image below). Taking the OSM image as a reference, this point should actually be at (1493539,6893156) (roughly where the bottom point is).
Why are these layers not aligned? The potential causes I have considered are:
- EPSG:3857 is incompatible with the CRS (EPSG:25833 - ETRS 89 UTM Zone 33N) of the point layer. But I pulled a set of street data from the same provider (which uses the EPSG:25833) and it is reprojected so that it accurately matches the streets in the OSM data.
- I have a poor combination of CRS and/or am using the wrong CRS for the project.
- The data source ("emissions") is somehow broken.
- There is a bug in QGIS :P
This installation is using proj 5.2.0 and GDAL 2.3.2.
EDIT: The cause turned out to be an error in the data source.