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Improving the quality of OSM using the GNIS data set

Posted by watmildon on 3/2/2023

Some background

If you’re new to this wonderful dataset I encourage you to read the OSM GNIS wiki entry or play around with the public GNIS web portal. Try feature ID 1629903!

The most important bits from a summary record are the feature Name, Class, and Coordinates.

Last fall, a group of mappers coordinated to address the name updates for Department of Interior Secretarial Order 3404. We cobbled together a collection of data scrapers and spreadsheets and declared victory a few weeks later. Since then, Kai and I have been thinking “there has to be a better way”.

What can the matcher do?

For any entry in the GNIS National File we can ask the matcher to search OSM. It does this using a private Overpass instance and a set of heuristics about likely tag combination and feature types. With reasonably high fidelity we can:

  • Find GNIS entries that are very likely not yet added to OSM
  • Find OSM objects that look incomplete or incorrect
    • Missing GNIS tag
    • Missing/different name from GNIS
    • Have a geographic bounds that does not agree with GNIS
  • Generate MapRoulette challenges for subsets of the full GNIS dataset

What does it look like in practice?

We’ve generated a handful of MapRoulette challenges to check the functionality and see how it improves mapping. Here’s some examples that show off different feature types:

Sq___ Rename Validation - Final cleanup of rivers and other natural features listed in Department of Interior Secretarial Order 3404. It’s very good at noticing if a named waterway is mapped up the wrong tributary.

King County WA Place Update and San Diego County CA Place Update - Urban neighborhood names for the most part. This kind of task really does require local knowledge as the geo information for this class isn’t super precise.

Add and update Mobile Home Parks in AZ - Also from the “place” feature class but for an under-mapped feature type in OSM. This one ties nicely into a project run by MapSwipe and YouthMappers.

What’s next?

We would love any and all questions/feedback you have! If there’s a feature class you’re super interested in, let us know. If there’s a particular area/region you’d like to check all the GNIS entries for, let us know. If mountains are your jam and you want to map the 10% of “Summit” entries that aren’t on OSM, let us know!

PS, if you like this idea… you will LOVE Edward Betts’ OSM wikidata matcher!