[OSM-dev] map projection and scale distortion

Iván Sánchez Ortega ivansanchez at escomposlinux.org
Wed Apr 16 17:42:33 BST 2008


<quote who="Tom Hughes">
> Iván Sánchez Ortega <ivansanchez at escomposlinux.org> wrote:
>
>> Yes, the slippy map scale should change with the latitude in
>> focus.
>
> Well that rather depends really - the amount the scale changes by
> depends what direction you are measuring in.

And even more, it depends on the pixel you're looking at - pixels at the
top of the map have a different scale than pixels at the bottom of the
map.

I dare to raise the question: Does a scale bar make any sense at all in a
map with an spherical mercator projection?

>> However, keep in mind that OpenLayers 2.6 was released, and deployed
>> into OSM's slippy map just today - give it a couple o' days, and the
>> scale bar will change depending on the latitude.
>
> I doubt that because (a) somebody would have to write code to make
> it dynamic and (b) somebody would have to convince me to patch our
> copy of OL instead of waiting for the next release ;-)

My bad, I just supposed that the feature was already in OL 2.6 and that
the deployment into OSM's slippy map was a bit hasty. O:-)


Cheers,
-- 
Iván Sánchez Ortega <ivan at sanchezortega.es>

Un ordenador no es un televisor ni un microondas, es una herramienta
compleja.




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