[OSM-talk] OSM in Europe Statistics

Wed Apr 30 09:32:10 BST 2008

Hi,

One funny alternative would be to compute not the size of the data (nodes and tags) but the size of the tiles in a compressed format (PNG or JPG or compressed BMP). An empty tile can be compressed to a few bytes, but a dense tile with a lot of ways and place-names cannot be compressed so much. In this way, we would compute the amount of "graphic information" available for each country/zone, and this would not be influenced by uploads of tracks with too many nodes or untagged, disconnected nodes.

On the other hand, one very visible difference between Mediterranean cities and, for example, English cities is the population density of the urban areas. For example, a medium-size English city like Liverpool is probably almost as big as Barcelona, even though their population is much smaller, so the ratio kms of streets divided by number of people will be very different in the South and in the North of Europe... not to mention those endless suburbs in the United States, for example...  so yes, it's very complicated to compute a map quality index properly.

Regards,
Lucas

________________________________

De: talk-bounces at openstreetmap.org en nombre de Frederik Ramm
Enviado el: mié 30/04/2008 1:45
Para: talk at openstreetmap.org
Asunto: [OSM-talk] OSM in Europe Statistics

Hi,

   a very crude statistic:

Country       osm.bz2 size    population    ratio (bytes per capita)
--------------------------------------------------------------------
UK                73M            60M                1.2
Germany          110M            82M                1.3
Netherlands       51M            16M                3.2
France            29M            60M                0.5
Finland           20M             5M                4.0
Italy             14M            58M                0.2
Norway            21M             5M                4.2
Sweden            24M             9M                2.6
Spain             17M            40M                0.4

I suspect that disregarding the coastline (which is included in my
figures) would probably cost the Scandinavian countries a few ranks in
this league. Coastline factor doesn't affect larger countries that much
(but still strange that Italy should have so little - must investigate
quality of border polygon).

It is probably not unreasonable that once the road network is complete
in a European country, we'll look at a ratio not unlike the NL figure.
This would suggest that both the UK and Germany are about 1/3 there.

Of course this is very simplistic and I believe you will come up with
much better measures of progress. Let's hear your numbers ;-)

(Among other things, NL is known as a very densely populated place - UK
has 9 times the area of NL but only 3 times the population -, so those
map features that tend to fill the available land even if sparsely
populated will mean that the "destination bytes per capita" ratio for
places like UK or DE will be higher than 3.)

Bye
Frederik

--
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"

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