You chose an area to map, print it, walk outside with the paper copy and mark things up, then scan or take a pic with the QR code and it’s added as a layer to OpenStreetMap (OSM). From there you can add your data to the largest public, editable map in the world.
It’s a project from Stamen and the U.S. Agency for International Development (USAID). Because it’s an open-source project whose last major changes were made five years ago and many tutorials showed the previous interface, it seemed like a good idea to test drive it.
The quick slideshow above shows how it works, the test run taking about an hour total, from figuring out how to position the map grid to editing in OSM.
It’s been used around the world for large mapathons, where people don’t have smartphones or OSM knowledge — you hand them sheets, they go out mapping, then they hand in the sheets and they’re done. It can be a potential bottleneck for OSM data entry after collection, but surmountable. Potentially it’s also an advantage — you can get a lot of people out mapping but only need a few with OSM knowledge or who want to learn.