[OSM-dev] Too many decimal places in permalinks

Tom Hughes tom at compton.nu
Tue Oct 23 11:56:39 BST 2007

In message <C99BFB9F-688F-46D4-9588-2415A4EEDE65 at mckerrell.net>
        John McKerrell <john at mckerrell.net> wrote:

> That's within 3 pixels of the position at zoom factor 2 though.  
> Actually as I try it out I see that I'm having to push it to get  
> something bad, e.g., "here's a map of Lime Street Station in  
> Liverpool, I've zoomed out a bit to give you some context but zoom in  
> and you'll see where it is":
> http://www.openstreetmap.org/?lat=53.41&lon=-2.98&zoom=6&layers=B0T
> As you see, I had to zoom out quite far to get it to break by not  
> very much, but I'd argue it's not worth losing the accuracy anyway,  
> there might be more problematic cases I'm not thinking of (e.g., if I  
> copied the lat/lon fields from that link to get a marker, the marker  
> would then be off).

Well yes, if you take that zoom 2 example and zoom in to zoom 17 (on
my display) then the station slips off the edge.

Who is going to send somebody a z2 link and tell them to zoom
in 15 times to see the relevant detail though? If you said somebody
a z2 link then you're trying to show them something large scale. If
you wanted to send somebody a map of Lime Street Station then you
would send them a z16 link or something sensible like that.


Tom Hughes (tom at compton.nu)

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