I am using the scale bar of the QGIS composer (ver 1.8) and I don't understand how the whole thing works.
Where can I set the units properly? The layers have idential CRS (WGS84), the settings for map tools is in meters.
I have tried to get it correctly by changing segment size and map units per bar unit, but it doesn't work. However, I have to admit that I don't understand what these two fields actually mean.
Best Answer
WGS84 uses degrees as units. It is not possible to add a meaningful scalebar with meters/feet to a map which is projected to WGS84. Choose a different CRS (with units in meters/feet) and the scalebar should make more sense. If you want to stick with WGS84, just get rid of the scalebar. What would it be useful for anyway?
This thread discusses CRS for the northern Atlantic What's the best projection for rasterization of random latitude and longitude data in the northern Atlantic?