[OSM-talk] JOSM and scale

[Lars Aronsson]

At the equator, each degree of latitude or longitude represents a 
distance of 111 km.  At latitude 60° (N or S), each latitude 
degree is still 111 km but since cos 60° = 0.5, each longitude 
degree is just half of that or 55.5 km.

In JOSM, when I use the Mercator projection method, look at the 
equator and zoom out until the little scale bar in the top left 
corner is 111 km, the difference in longitude between the ends of 
this bar is one degree.  That's fine.

But if I look at 60° N (e.g. Stockholm) and repeat the exercise, 
the end points of the 111 km scale bar is still one degree.  
That's an error, it should be two degrees.  Or rather, when the 
bar represents one degree, the label should say 55.5 km instead of 
111 km.

I've never cared too much about that scale, but now I know that 
these apartment buildings along Syrengatan are 11 x 32 metres and 
not 22 x 64 metres as JOSM would lead you to believe, 
http://www.openstreetmap.org/?lat=58.407&lon=15.600&zoom=17&layers=0BFT

Also, returning to cycle lanes, the "secondary" road 
Malmslättsvägen is now marked with cycleway=lane, but this doesn't 
show on the map here.  And how can I indicate that this bus stop 
is only on the southern side of the street (buses going east)?  
Buses going in the other direction stop at another place.

"Micromapping" is fun.  I want zoom=18 now.  Hmmm... and higher 
GPS accuracy.


-- 
  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se