[OSM-dev] Extracting Great Britain and Ireland from planet.osm

Ludwig M Brinckmann ludwigbrinckmann at gmail.com
Tue Mar 13 09:50:00 GMT 2007


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.

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.

Ludwig

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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