Mapping parties are great fun and it’s nice to show how much work the people involved put in.

Maybe we should have some type of a map to do this easily? Well, there’s some tools out there already see these questions 1 2.

But these solutions don’t quite cut it, and we want a nice customised map. So let’s use the new date/attic data features in Overpass API. Video explaining them here.

So let’s try it, stick this in your web browser:

overpass-api.de/api/interpreter?data=[diff:"2014-06-23T00:00:00Z"];node(55.877838662652906,-4.343075752258301,55.900317043029,-4.297800064086914);out meta;

This gets all the changes made to nodes in that bounding box between 23/06/2014 to the present time. The query returns osm xml file. So just add ‘.osm’ to the end of the file and load this into JOSM or QGIS and were ready to go, right? Nope, the file isn’t a standard .osm file. I couldn’t get it to load in JOSM or QGIS. So no problem. Let’s convert to GeoJSON. Okay, there’s a few ways to do this. OGR2OGR is a command line tool and there’s a few javascript osm to geojson libraries. Great, now we a rocking. Ah, hang on one sec. I found it difficult to make these tools retain the ‘meta’ data - e.g. the userID and name of the user who last modified the feature. And we want the meta data so we can credit people who have made the edits not just show where the edits were made.

I found this tool was easy to download and gave the option for meta data:

http://tyrasd.github.io/osmtogeojson/

Install this at command line:

$ npm install -g osmtogeojson

and try something like:

$ osmtogeojson Anniesland.osm > Anniesland.geojson --flatProperties

Brilliant. We can now stick the .geojson in QGIS or Tilemill and make a map:

…looks like overpass api can be used for some nifty stuff, maybe animated snapshots by hour or days….go play.