[OSM-dev] Massive building import - thoughts
frederik at remote.org
Fri Feb 6 22:29:49 GMT 2009
sly (sylvain letuffe) wrote:
> In france, next to the cadastre's agreement of using their data for OSM, we
> might soon be able to import something like 60% of France's builings.
Assuming that most houses will have 4 nodes, you're talking about
importing roughly 10 million ways and 40 million nodes.
We currently have about 304 million nodes and 25 million ways. Your
import would raise that to 344 million nodes and 35 million ways;
looking at the recent development, you would be importing half a year's
worth of normal OSM growth within, perhaps, a month or so.
On the whole it seems to me that there is nothing to worry on the
database side, provided of course the import itself does not use too
Your import would have a node:way ratio of 4:1, whereas the current data
has about 12:1 (after the import it would be 9:1). This is probably not
a cause for concern. You would be importing about 80 nodes per square km
on average. France would jump from 5 million nodes total to 45 million
nodes total, from an average of 10 nodes per square km to an average of
90 nodes per square km. The Dutch are already at 100 nodes per square
km, and I don't hear them complain, so it seems that such a data density
can be handled sufficiently by the existing tools.
I would imagine some complaints from those users who are not interested
in buildings, and for whom 90% of the data they download is useless
after the import. You might have to provide filtered extracts for them.
Frederik Ramm ## eMail frederik at remote.org ## N49°00'09" E008°23'33"
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