Using Josm's validator to check boundary relations
Posted by SomeoneElse on 21 March 2025 in English.Lots of people use editors such as iD, Potlatch, Vespucci, GoMap!! etc. for editing. There are entirely sensible reasons for this - I’ll always try and edit relations in Potlatch or iD since for me editing relations there is a much saner experience than in Josm. However, one thing that they miss is Josm’s Validator, which can check for relation errors that other editors can’t. Here’s how to use that to detect problems, and then fix them elsewhere.
I’ve created some test data on the dev server for this, so that I can deliberately create and fix errors. If you want to test with that data on the “dev” server, you’ll need to create an account there and tell Josm to login to that server - or you can just look at the screenshots below.
First, you’ll need to download Josm (I just downloaded the latest .jar file) . Josm’s user interface will be familiar to anyone who used CAD software in the 1980s, but may be less so to others.
Then you’ll need to download some data in the area that you were editing (file / download data / download). So that you can see what is where, it helps to have a background layer - “OpenStreetMap Carto (standard)” will work, or you can use an imagery layer if you prefer. Zoom in to your area of interest, select with the mouse and “download”.
Then click “validate” (on the row at the very bottom right of the screen).