[QGIS-trac] Re: [Quantum GIS] #1875: A few problems with crs definitions with TOWGS parameters

Quantum GIS qgis at qgis.org
Wed Aug 19 13:02:32 EDT 2009

#1875: A few problems with crs definitions with TOWGS parameters
        Reporter:  lutra                                      |         Owner:  homann       
            Type:  bug                                        |        Status:  closed       
        Priority:  critical: causes crash or data corruption  |     Milestone:  Version 1.2.0
       Component:  Projection Support                         |       Version:  HEAD         
      Resolution:  fixed                                      |      Keywords:               
Platform_version:                                             |      Platform:  All          
        Must_fix:  No                                         |   Status_info:  0            
Comment (by hamish):

 Replying to [comment:43 homann]:
 > Again, the WKT you have supplied is not translated by OGR into
 > the proj-string you think it should be. OGR library is used
 > for that. The proj-string is then used by PROJ4 to do the actual
 > projection. OGR library is used for that translataion also.

 Ok, got it.

 > If you use the GDAL/OGR program "testepsg <your-WKT-definition>"
 > you will see that OGR does not pick up the datum.

 Well, at least it got the SPHEREOID[] numbers correct...

 for the archives, my testepsg setup,
 GRASS65.svn> gdal/svn/trunk/apps/testepsg "`g.proj -wf`" | less

 > The error (if any) is reproducable outside QGIS. If you are sure
 > the WKT is correct, please file a bug with OGR, where the problem
 > (if any) can be solved.
 > Posting more comments here will not fix the problem.

 It is not my intention to spam the ticket or waste anyone's time, only to
 smash away at the problem until I/we/them understand it and each other
 well enough to solve the thing. :)

 Replying to [comment:44 warmerdam]:
 > Reviewing the ogr_srs_proj4.cpp code the +datum=nzgd49 is only
 > generated when exporting to PROJ.4 if a 6272 datum authority
 > code is present in the WKT. There is no attempt to recognize
 > this datum by datum name.


 > If you wish to take exception to this you might want to file a
 > ticket in the GDAL/OGR trac. I'm willing to contemplate improved
 > logic.

 patch filed as gdal/ogr ticket # 3104 for your consideration.


Ticket URL: <https://trac.osgeo.org/qgis/ticket/1875#comment:45>
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