[OSM-dev] Extracting Great Britain and Ireland from planet.osm
nickblack1 at gmail.com
Tue Mar 13 11:04:16 GMT 2007
On 3/13/07, Ludwig M Brinckmann <ludwigbrinckmann at gmail.com> wrote:
> Thank you, thank you, thank you.
> While I have not tried it yet, scripts like this will make OSM usable again
> for those who actually want to use the data (wasn't that one of the main
> goals?) When - at a recent mapping event - I was told by one of the key OSM
> people 'Who wants to download the whole of London?' when I complained that
> the API does not work for this anymore I seriously began to doubt the
> project's sanity. And stopped using it -- life is a bit too short.
The "sanity" of the decision to cap downloads based on the number of
features was that the API was being hammered by large request and
consequently was not functioning. The "insanity" would have been to
ignore the situation to the point where only those people who happen
to have a script on cron at 4am can download anything, whilst someone
trying to do a bit of mapping at lunchtime, can't get the applet
download any data because the API is being nailed.
> Two suggestions:
> 1) have this script generate the gb/irl data on the server and store it next
> to the planet.osm. This will seriously cut down the amount of data have to
> download and make it easier to work with up to date data. I assume there
> will be a lot of interest in the UK/IRL/Germany only data.
> 2) start a collection of interesting polygons (cities, counties, regions
> etc). While it might not make sense producing the cut down data files for
> all these polygons, it will help people get started.
> On 3/13/07, Keith Sharp <kms at passback.co.uk> wrote:
> > Hello,
> > Following on from last weeks discussion about reducing the size of the
> > planet.osm data set for particular use cases I have modified a script
> > written by Frederik Ramm that extracted data for Germany so that it
> > extracts data for Great Britain, Ireland, the Channel Islands, the Isles
> > of Scilly, St Kilda, Orkney, and Shetland. The polygon I used can be
> > seen:
> > http://www.passback.co.uk/maps/gbirl.html
> > You can download the script from:
> > http://www.passback.co.uk/maps/extract-gb-irl.pl
> > You run the script as follows:
> > ./extract-gb-irl.pl < planet-070307.osm > gb-irl.osm
> > On my system a run took just over 5 minutes wall clock time, I have not
> > looked at memory usage in any detail, but it looked about 50MB max
> > resident size in top (not the best measure, I know). The uncompressed
> > file is reduced from 3.40Gb to 0.22Gb, bzip2 compressed size is 16Mb.
> > I have done a little checking of the data and it looks like it is
> > working as expected, but I would appreciate if others could check as
> > well. Would it be possible to get the script added to the OSM SVN,
> > preferably next to Frederiks script.
> > A final question, I created the visualisation of the polygon in Google
> > Maps because I could not see how to do the same thing using the OSM
> > infrastructure, am I correct in thinking that there is no public API for
> > OSM at this stage?
> > Thanks,
> > Keith.
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