[OSM-talk] Area tags in Overpass API

Roland Olbricht roland.olbricht at gmx.de
Fri Mar 22 22:38:01 UTC 2013


Hi all,

> I'm also curious about the motivation for considering only a strictly
> limited subset of the areas in the database in the first place.
> Presumably this is because maintaining a large number of areas would be
> detrimental to performance?

First of all, thank you for taking it here. This allows for a in-depth 
discussion.

The performance was the initial reason to use a whitelist at all. However, the 
performance has since been a lot improved, and it could be, with some hours of 
programming effort, improved even more.

The reason to choose objects with name was that all use cases so far have been 
variations of the question "Where am I?". And without a name or other 
distinctive tag value, the area has been considered to be of little use.

The deeper reason is that I would like in general to let Overpass API be tag 
agnostic. The areas are one of the few places where I haven't found a way to 
get areas without tag evaluation.

And there is even a future driven reason to encourage feedback: In the long 
term, Overpass API will produce GeoJSON to allow vector rendering. The main 
roadblocker for this is the distinction between linestrings and polygons. I 
assume that an established list of tags that designate areas are the best way 
to achieve this with long-term stable semantics.

Cheers,

Roland




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