Dealing with historical data in OpenStreetMap

OpenStreetMap history challenges – methods – reasons

Relevance of Historical Data What did the map look like two years ago? Who was involved in editing object X / region Y? What exactly happened in changeset Z?

Relevance of Historical Data Historical visualization Retracing vandalism Data analysis

OpenStreetMap consists of • nodes • ways • relations

• nodes• ways• relations each of those have a version and a timestamp, among other things

each of those have a version and a• nodes timestamp, among other things• ways• relations So in theory it’s possible to recreate the full history of all objects in OpenStreetMap

in practicethis is morecomplicated

in practicethis is morecomplicated ways and relations only have references to node IDs

in practicethis is morecomplicatedways andrelations this poses twoonly have problems.referencesto node IDs

1. Moving a node does not cause a new way version

1. Moving a node does not cause a new way version 2. References in ways and relations do not point to a speciﬁc version

way version 11v1 3 2 v1 v1 1. Moving a node does not cause a new way version

way version 1 2 v21v1 3 v1 1. Moving a node does not cause a new way version

2. References in ways andrelations do not point to a speciﬁc version

Also, the data is not readily accessible

Also, the data is not readily accessible Full history dump is 451GB of XML, containing 1.7 billion node versions, 170 million way versions, and 4.5 million relation versions.

What is needed?

What is needed? • A suitable DB schema • PBF format support • importer (support)

What is needed? • A suitable DB schema • PBF format support • importer (support) .....and ideally, a history API

• A suitable DB schema• PBF format support• importer support (osmosis, imposm)

• A suitable DB schema• PBF format support• importer support (osmosis, imposm) History Hack Weekend http://bit.ly/osmhistoryhack

History Hack Weekendhttp://bit.ly/osmhistoryhack June 10-12 LinuxHotel Essen, Germany

thanks OSM > mvexeltwitter > @mvexelMartijn van Exelall photos from ﬂickr commons

Dealing with historical data in OpenStreetMap

by Martijn van Exel

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