A Google Earth hiking map for the Säntis region with Open Street Map data

After I have loaded a Switzerland pbf file (see download-switzerland-pbf.py or download-switzerland-pbf.bat) into an sqlite database (see OpenStreetMap: convert an pbf to an sqlite database with Python ), I can use this data to create a Google Earth kml file that highlights objects found in Open Street Map.

I am particularly intersted in creating an SAC hiking map for the Säntis region. For that end, I chose osm ways that have a tag named sac_scale.
Additionally, I restricted the respective nodes to the lattitude longitude for the Säntis region.

These ways are kept in a specific table:

create table sac_ways_around_saentis as select distinct wy.id way_id from tag tg join way wy on wy.id = tg.way_id join node_in_way nw on wy.id = nw.way_id join node nd on nd.id = nw.node_id where nd.lat > 47.2210118322 and nd.lat < 47.2604651483 and nd.lon > 9.3149215728 and nd.lon < 9.3959004678 and tg.k = 'sac_scale'

With this table, I can now extract the lattitude/longitude pairs for each node in the relevant ways and write them into a kml file.

The algorithm basically boils down to:

select way_id from sac_ways_around_saentis -- with each way_id: select node_id from node_in_way where way_id = ? order by order_ -- with node_id select lat, lon from node where id = ? -- Emit lat, lon into kml file

Of course, I would use a Python script for this (sac_ways_saentis.py on github).

Here's a screen shot of the result: