[OSM-talk] JOSM and scale

Robert (Jamie) Munro rjmunro at arjam.net
Tue Mar 25 17:26:30 GMT 2008

Hash: SHA1

Juan Lucas Dominguez Rubio wrote:
| Yes, they are probably using the same scale bar for WGS84 and Mercator.
| As far as I know, in WGS84, the scale bar is correct vertically (lat),
| but in Mercator, that scale bar is wrong both vertically and
| horizontally if you are far away from the Equator.
| As you say, one easy way would be to consider the latitude of, for
| example, the center of the map when calculating the length of the
scale bar.

Please make the scale bar accurately measure what is under it, rather
scaling it to the center of the map. I like to move the map around so
that things are near the scale bar to get an approximation of how big
something is.

If the scale bar cannot be to within about 5% of correct for the whole
screen (e.g. when zoomed out to see the whole world), I think it should
be hidden, or maybe some kind of max and min scale could be shown -
perhaps with another scale bar at the bottom of the screen.


Robert (Jamie) Munro
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