[Qgis-user] QGIS GNSS NMEA Transformation Problem WGS84 to MGI Austria

[Peter Hartl]

Thanks, answers below 

Von meinem iPhone gesendet

> Am 08.02.2025 um 19:35 schrieb Greg Troxel via QGIS-User <qgis-user at lists.osgeo.org>:
> 
> Peter Hartl via QGIS-User <qgis-user at lists.osgeo.org> writes:
> 
>> QGIS interprets NMEA data as WGS84 geographic data which is correct!
> 
> No, it is not correct.  It is only correct it the receiver is operating
> in WGS84.  That is true *only* for non-differential solutions.  That
> means not with SBAS, not with RTK.
> 
> And, it's also not correct because WGS84 is an ensemble.

I use EMLID Receivers with RTK, in their Software EMLID Flow and QField it Works perfekt
> 
>> I could not find to say to QGIS that it should use ETRS89 datum!
> 
> I think that's a missing feature.  The feature is missing in QField too:
> 
>  https://github.com/opengisch/QField/issues/2855
> 
> 
> There's another problem, which is that proj, when asked to transform
> from WGS84 to NAD83(2011) 2010.0, uses a null transform.  That
> technically makes sense because WGS84(TRANSIT) is roughly equal to
> NAD83(1986).  But it doesn't actually make sense.
> 
>> We are using *QField*, here Transformation in X, Y from GNNS into our
>> MGI with gridshift is working correkt (Vertical girdshift works too
>> very goo in cm accuracy)!
> 
> But what is the actual datum your NMEA is in?  What kind of GNSS are you
> using?
> 
I use EMLID Receivers with RTK, in their Software EMLID Flow and QField it Works perfekt!
Will Check next week which Datum is used in Receivers!

>> The *same QGIS projekt behind with QGIS* shows data in map correct
>> (set to 25832) but in saving to 31254 it gets shift, without
>> possibiltity for changing that for me.
>> 
>> For me it looks like a issue in QGIS!
> 
> Maybe but you have not answered my questions about what is really going
> on, and you may be operating in a mode where multiple bugs sometimes
> cancel and sometimes do not.

I use QField, is perfekt no need for QGIS with GNSS.
Just wanted to know why nearly same Software behaves different with same Input data!
Until now I found no Solution in QGIS (I Like it)!

Greeting
Peter
> _______________________________________________
> QGIS-User mailing list
> QGIS-User at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user