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Fixing Polygons in OSM

As of August 2017 this effort has now been finished! Thanks to everybody who contributed. See some results in this blog post. I'll keep this repository around for the time being.

There are many different ways (multi)polygons in OpenStreetMap can be mapped correctly and there are even more ways in which they can be mapped incorrectly. Of the over 220 million (multi)polygons in OSM more than 100,000 contain mapping errors of one kind or another and about 250,000 are tagged old style with tags on the outer ways instead of on the relation making multipolygon tagging and processing much more complicated and much more expensive than it needs to be.

We are trying to fix all this and this repository is here to organize this effort.

Note that this is not about inventing some new way of representing (multi)polygons in OSM. This is about fixing wrong tagging and simplifying the current way of tagging. There are no changes needed or planned to the core of OSM.

This will make mapping easier, because there will be only one canonical way of tagging multipolygons. Editors can take this into account and help mappers in better ways. And it will make using the data easier and faster because the programs (such as Osm2pgsql and Osmium) converting OSM data into multipolygons for rendering or other uses can be simplified. It will also make it easier to detect mapping errors raising the quality of the OSM data.

Database and extracts

Start fixing things

Read this for instructions.


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If you have any questions or want to contribute in any way, here are some ways to get involved: