[OSGeoLive] Mis-projection in OSgeo-Live 16' QGIS only

Even Rouault even.rouault at spatialys.com
Wed Sep 25 09:19:07 PDT 2024 

Jochen,

I just looked at your shapefiles. The issue is not with the CRS. It is 
with the actual geometry coordinates. They are all in the [0,1000] x 
[0,1000] range, which is totally outside of the area of validity of the 
CRS (the false easting / northing valus of the CRS are 400,000, so close 
to 0, you're 400 km off the center of the projection). So displaying it 
offboard of France is the *right* thing to do. There must be have some 
processing done at some point on your original shapefiles to alter their 
coordinates and normalize them to [0,1000].

Even

Le 25/09/2024 à 17:04, Jochen Albrecht a écrit :
> Dear Brian:
>
>     how is it that you have never reached out before today?
>
>
> Because the problem occured only this week and I spent the last two 
> days trying to figure out what is going on. The last time I used this 
> lab exercise was a year ago, and hence with OSgeo-Live v15.
>
>     did you take any steps to identify what projection system is being
>     used to misplace this shp file?
>
>
> QGIS (as well as ArcGIS) claim that they are using the correct 
> coordinate system.
>
>     did you try to install and run any other version of QGIS on this
>     version 16 base, in any way?
>
>
> No, I did not because I am trying to avoid this for the sake of not 
> killing the carefully aligned libraries of OSgeo-Live.
>
> I am attaching the mini archive of the sample data that now causes 
> these problems. I am also attaching screenshots of the automatic 
> pop-up window when I load the same file into the stand-alone version 
> of QGIS, which prompts me to confirm a coordinate system 
> transformation procedure.
>
> Cheers,
>       Jochen
>
> transform1.png
> transform2.png
>
> On Tue, Sep 24, 2024 at 7:22 PM Brian M Hamlin <maplabs at light42.com> 
> wrote:
>
>     Dear Dr Albrecht -
>
>       this is the first time I have heard of this issue.. we are
>     building the newer, alpha1 version 17 now using a newer QGIS LTS. 
>     Due to this combination of factors, your email raises more questions
>
>     * how is it that you have never reached out before today?  no one
>     on the #osgeolive team can know all the places that the disk is
>     used. If I understand, this condition of one particular QGIS
>     misplacing a shp file would have been the case on the day that
>     version 16 was released?  therefore you have taught many times yet
>     never one email here. Why now, on the week that we start the
>     anticipated alpha1 version 17 based on Ubuntu noble and GDAL v3.9x.
>
>     * did you take any steps to identify what projection system is
>     being used to misplace this shp file?  for example, does it say in
>     the bottom corner of the window of QGIS ?  do you have any guesses
>     as to what the errant projection might be, and if so did you
>     include that in your description of this bug, below?  maybe I 
>     missed a section..
>
>     * did you try to install and run any other version of QGIS on this
>     version 16 base, in any way?  I am not a QGIS expert but I am
>     guessing there are several alternatives that would install something.
>
>        today I am busy running and testing a build of #osgeolive 17,
>     which promises improvements and stability.. as with the dozen or
>     so #osgeolive linux that have shipped reliably, without cost to
>     you, for the last decade.
>
>        --Brian M Hamlin    /  MAPLABS  /  OSGeoLive PSC
>
>
>
>     On 9/24/24 11:13, Jochen Albrecht via osgeolive wrote:
>>     Hi
>>
>>     I am teaching with the latest version of OSgeo-Live 16, which
>>     runs QGIS 3.28.
>>     I am using for my class a small demo shapefile, which happens to
>>     be in EPSG:31287 (Austria, Styria). QGIS 3.28 places this file
>>     into the Mediterranean Sea, off the coast of Italy/France.
>>     Earlier versions of QGIS (in previous years of teaching), as well
>>     as my current stand-alone version 3.36 are placing the data
>>     correctly into the province of Styria in Austria. The problem
>>     occurs only in version 3.28.
>>
>>     The problem is aggravated by the fact that any attempt at
>>     transforming the data is rendered futile in this particular
>>     version of QGIS because none of the reprojection dialogues allow
>>     me to specify a transformation. I even tried to define a new
>>     coordinate system using the transformation parameters given by
>>     QGIS 3.38 (see the bottom of this email). Applying these, places
>>     the data again into the Mediterranean.
>>
>>     I have been teaching with QGIS for over 20 years, and this is a
>>     new one for me. The easy solution would be to just not use
>>     version QGIS 3.28. But it is the one that has been burned into
>>     the current OSgeo-Live distribution. The whole purpose of
>>     OSgeo-Live is to work with versions of the individual software
>>     packages that have proven to play nice with each other and I do
>>     not want to experiment and have students upgrade to a
>>     newer version of GIS.
>>
>>     At this point, I am at a loss to advise my students what to do,
>>     or to even explain what is happening here. It is as if the
>>     particular coordinate system library for this version has a bug
>>     that nobody has come across before. Am I missing something?
>>     Last minute update: the same error occurs in the latest
>>     version of ArcGIS Pro 3.3. I have no idea what those two have in
>>     common, but it suggests to me that it has something to do with a
>>     flawed coordinate system library rather than the
>>     application software itself.
>>     Again, any suggestion for how to address this (or even explain it
>>     to my students) would be appreciated.
>>
>>     Cheers,
>>           Jochen
>>
>>     Dr. Jochen Albrecht, GISP (he/him/his)
>>
>>     Professor for Computational and Theoretical Geography
>>
>>     Department of Geography and Environmental Science
>>     <http://www.geo.hunter.cuny.edu/>
>>
>>     Hunter College CUNY
>>
>>     695 Park Avenue
>>
>>     New York, NY 10065
>>
>>     Immediate Past-President, GIS Certification Institute
>>     <https://www.gisci.org/>
>>
>>
>>     	
>>
>>
>>     Recently published: GIS and Housing: Principles and Practices
>>     <https://sites.google.com/rojasap.com/gisandhousing/>*
>>     *
>>
>>     _______________________________________________
>>     osgeolive mailing list
>>     osgeolive at lists.osgeo.org
>>     https://lists.osgeo.org/mailman/listinfo/osgeolive
>
-- 
http://www.spatialys.com
My software is free, but my time generally not.
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