Combine OpenStreetMap extracts

We discussed previously how to import a single OpenStreetMap extract and avoid processing the huge, complete OSM dataset. What if your area of interest is smaller than the whole planet, but larger than a single extract?

This is what the Luxembourg extract from the previous article looks like.

But what if we want Belgium, Netherlands and Luxembourg?

Osmosis to the rescue. Osmosis is a powerful tool with many options, we'll look at only at the merge option.

1. Download the extracts - These were from GEOFABRIK
• Belgium extract.
• Luxembourg extract.
• Netherlands extract.
2. Merge the extracts with osmosis.

cd ~/osmosis/bin/osmosis
./osmosis --rx ~/extracts/belgium.osm.bz2 --rx ~/extracts/netherlands.osm.bz2 --rx ~/extracts/luxembourg.osm --merge --merge --wx ~/mapnik/benelux.osm from this example you can see that the --read-xml task will work on the bz2-compressed files as well as plain .osm files. If you are merging only two .osm files, omit the second --merge.

3. Import the merged extract.

cd ../src/osm2pgsql/
./osm2pgsql --slim -d gis ~/mapnik/benelux.osm

4. Set your chosen bounding box in ~/mapnik/generate_image.py. I used ll = (2.54695,49.44722, 7.22760,53.62990) # Benelux
5. Render your custom area of interestcd ~/mapnik
source ./set-mapnik-env
./customize-mapnik-map >$MAPNIK_MAP_FILE
./generate_image.py

And enjoy your newly created, custom area of interest.

Credits

Article © 2009 CCBY R.Weait.
Map images and data © 2009 CCBYSA OpenStreetMap and contributors.