Urchn is like your friend who’s lived in the city forever. It’s a tool that uses persistent change monitoring to tell us where cities are changing, and where OSM is out of date. For planners and civil servants, it provides a building-by-building view on how neighborhoods develop. Above all, it’s a tool for mappers, and mapping campaign organizers, who need to know where they can make the most impact.

To power Urchn, we run consecutive overhead earth imagery passes through a machine recognition algorithm. This process filters out things like seasonal variation, and gives us outlines of newly paved roads, fresh building construction, and other persistent change. By overlaying this data over high-res imagery and analyzing it against a minutely updating OSM replication, we can detect in fine detail where a city has changed, and where that change requires a mapper’s attention.

When dense urban areas change faster than OSM volunteers can map, the result is a less useful map for everyone. We’re working with Radiant and Azavea to give mappers the tools to keep up with urban change. Urchn will be public soon, and we’d love to get the community’s feedback.