[QGIS-Developer] QGIS3: reminder of an annoying bug

[Tobias Wendorff]

Hi Jürgen,

thanks for your research.

Am Sa, 20.01.2018, 18:05 schrieb Jürgen E. Fischer:
> GDAL does detect the correct EPSG from prj it wrote itself.

Yes, this is true for GDAL, but as soon as the QPJ is missing,
QGIS switches back to 3044.

I figured out that adding AUTHORITY["EPSG","25832"] to the PRJ
makes QGIS parse it correctly. I'll write a small tool for my
co-workers. Or maybe even a QGIS plugin, which forces 25832
whenever 3044 is being detected. No good work-around :(

What about a feature to QGIS to force a CRS, if another one has
been detected? :)

> Apparently from the different name of the projection, because the
> rest of the prj is the same. There is no information about the
> different axis order in the prj (ie. the only
> actual difference between EPSG:3044 and EPSG:25832).

Yeah, see blow.

Axis order will matter with new Proj4. Many things will change/break
here in future. Also scripts might fail because of different CRS.

> How do your .prj actually look like?

I don't have ArcGIS PRJs at the moment. I can add them tomorrow.
I've completely switched from ArcGIS to QGIS some years ago.

Take this example from Geodatenzentrum:
http://www.geodatenzentrum.de/projektion/utm32s.prj

Funny, three names for the same projection:
- QPJ: ETRS89 / UTM zone 32N
- PRJ (QGIS): ETRS89_UTM_zone_32N
- PRJ (Geodatenzentrum): ETRS_1989_UTM_Zone_32N

> I guess we better let the user decide with CRS to use, when we
> don't find an accurate match.  Even if there wouldn't be so
> many duplicates, the frequency of> use may be different for
> different areas of application and any automatism might
> still fail and appear as a bug.

But even then, the user must be aware of which is the correct CRS.
I bet, it's complicated to code a notice to point out whether it
is a CRS of  national surveying or another...

Best regards,
Tobias