[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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Changes (by lutra):

  * keywords:  => scale, projections, measure line, measure area
  * owner:  nobody => timlinux
  * milestone:  Version 1.0.3 => Version 1.2.0

Comment:

 These are my latest observations on this annoying bug. Maybe a few of the
 following situations doesn't make sense at all (in these cases a warning
 should be issued?), maybe others are puzzling.


 == a) project in wgs 84, layer with a geographic system, OTFR disabled ==

 *) Map Units in Degrees: map scale seems right. Measure Line and Measure
 Area Tools seems to return right values.

 *) Map Units in Meters or Feet: map scale is wrong, as it seems to just
 exchange the value in degrees with the value in meters/degrees (ex: 30
 degrees -> 30 meters). Measure Line and Measure Area Tools return wrong
 values.



 == b) project in wgs 84, layer with a geographic projection, OTFR enabled
 ==

 *) Map Units in Degrees: map scale seems right. Measure Line and Measure
 Area Tools return wrong values (several times too big).

 *) Map Units in Meters: map scale is wrong. Measure Line and Measure Area
 Tools seems to return right values.

 *) Map Units in Feet: map scale is wrong. Measure Line and Measure Area
 Tools seems return wrong values (a few times less than supposed).



 == c) project in wgs 84, layer with a projected system, OTFR disabled ==

 QGIS notice you that as the project is a G.C.S. and the layer is in a
 P.C.S., Measure Line and Measure Area Tools will return wrong values.


 *) Map Units in Degrees: map scale is wrong. Measure Line and Measure Area
 Tools return wrong values (several times too big).

 *) Map Units in Meters: map scale seems right. Measure Line and Measure
 Area Tools seems to return right values, at least they are consistent with
 the values returned by other tools, for example Google Earth.

 *) Map Units in Feet: map scale is wrong. Measure Line and Measure Area
 Tools seems return wrong values (a few times less than supposed).



 == d) project in wgs 84, layer with a projected system, OTFR enabled ==

 *) Map Units in Degrees: map scale is wrong. Measure Line and Measure Area
 Tools return wrong values (several times too big).

 *) Map Units in Meters: map scale is wrong. Measure Line and Measure Area
 Tools seems to return right values.

 *) Map Units in Feet: map scale is wrong. Measure Line and Measure Area
 Tools seems return wrong values (a few times less than supposed).

-- 
Ticket URL: <https://trac.osgeo.org/qgis/ticket/1433#comment:5>
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