[OSM-talk] CLC2000

[Robin Paulson]

On 18/01/2008, Tom Hughes <tom at compton.nu> wrote:
> > why is this an issue? i would assume the link has to appear whenever
> > some of their data is displayed on screen? setting a tag to some
> > value, that then triggers a link to display at bottom-right should not
> > be too much of an issue. or is it some non-technical issue?
>
> I take it you're volunteering to write the code to track changes
> to tags and update a database that maps bounding boxes to attribution
> strings and then allows a set of strings to be retrieved on the fly
> to display over the slippy map as you move it?

not necessarily, i was asking the question to prompt some discussion
over the problem and some solutions. i'd love to do it, lots of ideas
in my head, but time is finite

> What do you propose to do when zoomed out to show the whole world
> and there are three hundred attribution strings to display by the
> way? It might be quite hard to see the map with them all displayed...

well, the serious answer to a flippant question begins with asking if
we can get away without showing them at these zoom levels? there's no
discernible/usable data at these levels - it appears to be turned off
by the renderers, so we can easily get away without showing it.

i had a quick look at google maps, gradually zooming out step-by-step,
and this appears to be what they do. there's only one attribution
string for world

and look for yourself at the main osm map zoomed out to 'world' -
nothing shows except land, sea and country boundaries. no data = no
attribution string

roads start showing at zoom level 5, so this would be a better place
to start looking at how many attribution labels there would be on
screen at one time.

and realistically, there are only going to be a small number of
compatible data sets that are usable, most are released under very
restrictive licenses, so the list of attribution strings will never be
that high - how many are there so far that are being considered?