[Qgis-user] print composer scalebar help?

[Carson Farmer]

Hi Ross,
> The print composer has me kind of stumped...
>
> What I'd like is a simple scale bar to indicate how long a mile (or 
> perhaps 2,5, or 10 miles) is on my map. The project units are in feet 
> (but I'm not sure that's relevant in the composer?).
No this doesn't matter to much to the composer, but it does to you...

Essentially all you have to think about is this:

If your map scale is say 1:20 000 (feet), then in the 'Map units per bar 
unit', you'll probably want 1, and in the 'Segment size (map units)' 
you'll likely want 20 000. This will give you a nice scale bar, and you 
can specify how many segments to display etc.

Now in your case, if your map units are in feet, but you want to show 
miles in the scale bar, then you have to do the conversion yourself. 
Since 1 foot = 0.000189393939 miles, or 1 mile = 5280 feet you can 
simply change the 'Map units per bar unit' value from 1 to 5280.

Now, if you are still getting funny things happening, it could be that 
your map units are indeed not in feet, in which case, you'll have to 
figure out what they really are ;-)

If I'm completely wrong here, please someone let me know, otherwise, I 
hope this helps...

Cheers,

Carson

-- 
Carson J. Q. Farmer
ISSP Doctoral Fellow
National Centre for Geocomputation (NCG),
Email: Carson.Farmer at gmail.com
Web:   http://www.carsonfarmer.com/
       http://www.ftools.ca/