[Talk-GB] importing house shapes

[Tom Chance]

On 19 October 2012 11:11, Richard Mann <richard.mann.westoxford at gmail.com>wrote:

> I'm wondering whether there'd be a case for a very small number of
> high-value (in terms of processing speed) relations to be created
> automatically, available to data consumers in the normal way through the
> API, but _not_ shown in editors? These relations really just make things
> more complicated.


I'm not a fan of the API creating output, it makes things confusing when
people using the data find data they can't see in OSM.

I would also say it is not just about processing speed, but also about
simplicity and accuracy.

In JOSM you can simply download all the objects in the relation, so you can
quickly get the full street data. There's no easy way to do this without
the relation.

For the more sophisticated data user, if you have to look for nearby
objects with the same addr:street tag, how far do you throw the net?
Sometimes a street is very short and has a unique name, so it's easy (e.g.
http://www.openstreetmap.org/browse/relation/967426). Sometimes a street is
pretty long, so you might have to keep widening the net until you're not
finding any more objects (e.g.
http://www.openstreetmap.org/browse/relation/933527). But beware - there
are other Lordship Lanes in London. With common road names like "London
Road" you'd have to be even more careful to look for objects adjacent to
roads that connect directly to the road you started out with, so you didn't
accidentally pull in objects next to a different but nearby London Road.

These problems are solved with the associatedStreet relation, which to my
mind serves a purpose more useful than redundant categories like "pubs in
London".

If the editors can make it easier to add the relations, that seems the best
solution to me. In my experience the trickiest bit is tracing all the
niggly shapes, especially for terraces, so the relation is the least of my
concerns.

Regards,
Tom

-- 
http://tom.acrewoods.net   http://twitter.com/tom_chance
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