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I use QGIS Lisboa and need the lenght of some shapefiles. When I use the field calculator the results are always around 30 % higher than in real, also than a measuring in the map. Does anybody have a similar problem or knows about a solution.

Thank you very much in advance!

Paul

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Which CRS are you using? –  nhopton Feb 23 '13 at 18:40
    
By "length of some shapefiles" do you mean the length of all features in each shapefile? I assume you are dealing with LineString features. –  steko Feb 23 '13 at 18:49
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1 Answer

Field calculator uses the CRS of the shapefile, while measurement tool uses the projects CRS, until you uncheck Use ellipsoid

The two CRS may be the same, or not.

You can right-click on the layer -> Set Layer CRS for Project, unless you are using openlayers plugin for background layer.

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I always was wondering which CRS it uses. Thanks –  nickves Jul 10 '13 at 1:13
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