[QGIS-trac] Re: [Quantum GIS] #2426: On-the-fly projection issues with large extents

[Quantum GIS]

#2426: On-the-fly projection issues with large extents
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        Reporter:  gislab                            |         Owner:  nobody       
            Type:  bug                               |        Status:  new          
        Priority:  major: does not work as expected  |     Milestone:  Version 1.5.0
       Component:  Projection Support                |       Version:  HEAD         
      Resolution:                                    |      Keywords:               
Platform_version:                                    |      Platform:  All          
        Must_fix:  No                                |   Status_info:  0            
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Changes (by lutra):

  * platform:  Windows => All

Comment:

 Well, you are right. I made a slightly different test:

 The vector you posted is defined in wgs84 crs and I exported it with
 "ftools" (I misunderstood your steps) to the system you describe, so I had
 obviously no problems.

 Now... your vector is geographically really wide(!), defined in a
 geographic crs, and what you do is to reproject it in a projected crs.
 Maybe the result cannot be the expected one, especially if/when the vector
 crosses/nears the 180◦ longitude line? Really not sure.

 [See also paragraph 5.2.6 of the qgis 1.3 user manual if you want to avoid
 to see the features crossing the 180º lon line separated from the others]

 Somehow related to #2349 ?

 In any case if you need the vector in the projected crs you describe, and
 the project in the same crs, an easy workaround is to export it to this
 projection with ftools, instead of having qgis reproject it on the fly.

 I'm not sure how arcview works, but I believe that gvsig (the only other
 gis program I can test now) works like it, but actually I can't understand
 its logic:

 I created a view and defined its projection as the crs you describe, then
 added to the view your vector "bnd-political-boundary-a". The vector shows
 fine (and no zoom problems), the only "detail" is that is not reprojected.
 It shows as in a wgs84 qgis project, but in the properties the vector crs
 is the one of the view.

-- 
Ticket URL: <https://trac.osgeo.org/qgis/ticket/2426#comment:4>
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