OpenStreetMap
www.openstreetmap.org
Jochen Topf

A community project
to map the world.

Worldwide project
Everybody can contribute
We are collecting geodata
Open tagging, no fixed schema
Free license (CC­BY­SA)

Berlin beginning of 2007

Routing / Navigation

Collecting GPS data...

Collecting attributes
● On foot, by bike, car, train, ...
● Tracks and waypoints
● Notes on paper
● Audio notes
● Photos
● Out of copyright maps

Aerial Images
● Aerial/Satellite Images
● From Landsat
● From Yahoo
● ...

Data model
● “The simplest thing that could possibly work.”
(Ward Cunningham)
● All data stored in central database
● Geometric objects
● With history

Data model
Nodes
Ways
Relations

Tags
waterway=river highway=stairs
highway=cycleway
highway=
residential
bridge=yes,
layer=1
leisure=
park
highway=
footway railway=
light_rail
highway=secondary
railway=halt

Data model
● Objects with
– A position/extent
– A number of Tags (key=value)
● No
– class/attributes
– complete list of attributes
– no ontology
– no hierarchy

Where do tags come from?
● Invented as needed by people needing them
● Discussion on mailing lists and wiki
● Documentation in wiki
● Voting process (mostly ignored)
● Reorganization needed?
● Coexisting schemes?

Rough consensus
We reject: kings, presidents and voting.
We believe in: rough consensus and running
code.
(David D. Clark)

Problems
● Tagging “for the renderers”
● Tagging only for current use of data
● Much of the available information is therefore
not stored and will be lost
● Might need costly re­acquisition of data

We don't need no metadata....
● No formal metadata
● Just freetext wiki explanations
● Work needed to extract usable data

Data mining
Full­text vs. meta­data
Google vs. Library
Data mining vs. lookup

Tagwatch
● Statistics about actual use
● Look at the data and infer metadata
● Needs large body of data
● Doesn't work for new tags

www.openstreetmap.org
www.geofabrik.de
Jochen Topf
jochen.topf@geofabrik.de
All maps in this talk are Copyright 2008 OpenStreetMap Contributors
The talk itself is Copyright 2008 Jochen Topf
Licence for maps and talk: Creative Commons CC­BY­SA