[OSM-dev] The Overpass Augmented Changesets API

[Roland Olbricht]

Hi all,

> http://www.webmonkey.com/2013/04/watch-openstreetmap-improve-in-real-time/

Cool! I could get addicted to sit down and watch every time again. A great 
thank you to Ian.
 
> So: questions.

Thank you for the hint. I have added at least some documentation at
http://wiki.openstreetmap.org/wiki/Overpass_API/Augmented_Diffs#The_augmented_diff_API_call
that answers the questions below:
 
> What does `info=yes` and `info=no` mean?

Boundary relations tend to bloat the Augmented Diffs: whenever a change 
somewhere on the boundary happens, even a minor one, the nodes and ways of the 
entire boundary are transmitted. This makes in turn the file one or two orders 
of magnitude bigger, without high profile information gain. The biggest one I 
have observed so far had more than 50 MB. With info=no, you can boil down file 
sizes but keep the geometry information for ways and nodes always intact.

> Does the BBOX argument work, and what argument order does it accept?

The OpenLayers order (lon,lat,lon,lat).

> Are there any other querystring
> arguments that might be useful - for instance, a limit argument would be
> wonderful, since right now the API returns 'all items', which is around
> 3.5MB gzipped per user per minute.

No, not yet. But I'm open to ideas although it may take some time until I can 
implement them.

In the long run, I would like to offer full history information on Overpass 
API, and the then-developed Diff format would be the format for the diff 
between the same query at two arbitrary moments of time. But this may take 
half a year or longer until I arrive there. This is the reason why I'm keen in 
getting the format and API as useful as possible.

For the limit argument: What should be the order to determine what to cut?

Cheers,

Roland