[QGIS-trac] Re: [Quantum GIS] #1433: measurements and scale broken in latlon

[Quantum GIS]

#1433: measurements and scale broken in latlon
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        Reporter:  msieczka                                   |         Owner:  timlinux                                      
            Type:  bug                                        |        Status:  new                                           
        Priority:  critical: causes crash or data corruption  |     Milestone:  Version 1.2.0                                 
       Component:  Projection Support                         |       Version:  HEAD                                          
      Resolution:                                             |      Keywords:  scale, projections, measure line, measure area
Platform_version:                                             |      Platform:  All                                           
        Must_fix:  Yes                                        |   Status_info:  0                                             
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Comment (by cfarmer):

 Replying to [comment:6 borysiasty]:
 > This is an important issue. Many users think the unit selector allows
 some kind of reprojection in the fly and feel confused.

 I agree, this is an important issue, and once a clear plan of action in
 set in place, likely won't take long to fix...
 >
 > Shouldn't we tie the units to the current CRS and take the selector
 away? Actually it's partially implemented: if I set the project CRS to any
 metric one and OTFR is enabled, the units are switched to meters
 automagically. But if OTFR is disabled, selecting a metric CRS doesn't
 switch the units.

 I don't agree here: I don't think the user should be tied down to the
 units of their input layer(s). If they want to calculate distance in
 metres or feet, then they should be able to calculate distance in metres
 or feet, regardless of the projection. This means that when a geographic
 CRS is used, distance/area calculations need to reflect this, and return
 the correct results (e.g. great circle distance).

 As far as I can tell, when using QgsMeasureTool, the QgsDistanceArea never
 has an ellipsoid set... is this correct?

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Ticket URL: <https://trac.osgeo.org/qgis/ticket/1433#comment:7>
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