Fossgis: vandalism in openstreetmap - Pascal Neis

Tags: fossgis, geo

(One of my summaries of a talk at the 2017 fossgis conference).

The number of daily users has almost doubled in the recent years.

Vandalism? Deleting an entire city block? You must distinguish between accidental changes and real vandalism. It is easy to try out an editor and change something in the real database.

  • Vandalism. Deleting items.

  • Bad editing behaviour.

    • Mass edits. Imports and bots.

    • “Edit wars”.

    • Missing knowledge. Trying things out. Adding material with the wrong copyright. Removing a railroad because it looks better on their map and not knowing that they’re editing the real map.

An example: pokemon. People thought that the pokemon app uses openstreetmap data to locate footpaths and parks. So suddenly people started adding parks and footpaths around their house. Luckily they often added “park for pokemon” in the comments.

He invested 15-45 minutes a day during a month to try and detect vandalism. Lists of new users: review their edits. For instance. The best solution if you see something that’s not right: ask them in a friendly way. Stay relaxed. As a second step, notify local mappers. As a last ditch measure: revert the edit.

What he saw:

  • 20% real vandalism.

  • 24% had already been reverted (but not documented and such).

  • 23% was test data.

  • 13% fictive data.

Regarding the answers he got back: out of 300 comments, he got only 70 answers. 20 of those were of the original author of the changeset. All those 20 answers were friendly! He did have to wait about 24 hours on average before getting an answer. So don’t expect an email right away.

He showed a lots of nice statistics. For that, you’ll probably have to look at his blog. Start at, you’ll find links to the tools he used there. For instance .

He has some ideas for future tools. Push instead of pull notifications. Coordination of reviews. etc. logo

About me

My name is Reinout van Rees and I work a lot with Python (programming language) and Django (website framework). I live in The Netherlands and I'm happily married to Annie van Rees-Kooiman.

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