[Wikipedia-l] Galileo and others

Wed Jul 14 18:40:22 UTC 2004

Tomasz Wegrzanowski wrote:
> Once we have the data, the software itself isn't that difficult.

Actually, you can do a lot of fun with geo coordinates even if you
don't have access to mapping data.  For example, you can compute the
distance between two coordinates or you can list coordinates that are
within close range of each other.  In an article on Napoleon, you can
follow every [[link]] and see if the pointed-to page has a coordinate,
then you can put all these coordinates as numbered circles on a map
overlay, to trace Napoleon's world tour.  Then add this overlay to a
map if you have one.

Just like ISBN: numbers can be useful with any different online
bookshop or even without any online bookshop, GEO: coordinates can be
useful with different online map sources.  This could be selected with
individual user preferences.  If I am a subscriber to a commercial
online map source, my personalized view of Wikipedia could render GEO:
coordinates as a link to that source.  Since the contents with the
GEO: coordinates is distributed under GFDL, another website can do
something else with the GEO: coordinates.

On http://susning.nu/Wroclaw the wiki text map:51.11:17.03:100000
(i.e. geo 51.11 N, 17.03 E) is rendered as a link to
http://www.mapquest.com/maps/map.adp?latlongtype=decimal&latitude=51.11&longitude=17.03&zoom=6

The difficult thing is to agree on the exact shape of the world
(ellipsoid, geoid).  Converting between Greenwich and Paris meridian,
between decimal and non-decimal degrees, or between different
projections is trivial. But is 51.11 and 17.03 the official center of
Wroclaw?  Or is it a few dozen meters off?  Mapquest seems to draw
this coordinate at the Ratusz (town hall), which seems like a good
choice, but another map source might have a different opinion.  What
does your GPS tell you?  And which coordinate should be in the
Wikipedia page?  This is where some knowledge about cartography could
be very useful. See
http://en.wikipedia.org/wiki/Map_projection#Choosing_a_model_for_the_shape_of_the_Earth

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