[Tagging] Points vs Polygons

Martin Koppenhoefer dieterdreist at gmail.com
Fri Apr 24 09:03:02 UTC 2020


Am Do., 23. Apr. 2020 um 17:14 Uhr schrieb Paul Allen <pla16021 at gmail.com>:

> I do not see why you would have to remove the address information from the
>> building when you add it to another object with the same address (like a
>> shop).
>>
>
> DRY.  Having the same address info for the building and the business
> makes it more likely that if the information is found to be incorrect only
> one of the copies will be corrected.
>


"more likely" is even an understatement, it will be impossible to have
different address information when there is only one object with address
tags, naturally. But if it is incorrect, you will have twice the errors.
When there are inconsistencies that could be seen in the data (like point
inside a polygon has different address), it can be used for quality checks
and someone can go there and verify which is correct. There are pros and
cons to both approaches.



>   I've had to fix enough addresses
> (mainly incorrect postcodes but sometimes incorrect or missing
> street names and even cities) that having the same information
> in two places is undesirable.
>


may depend on the kind of problem. For postcodes the situation may be
different than for housenumbers? In my context, it is also quite common to
have distinct housenumbers like 1 and 3 and 5, each as a node, each
assigned to entrances that lead into the same shop, while the business uses
either an address by choosing one of them (maybe the actual entrance, but
maybe the entrance it used to use years ago) or more commonly an address
like housenumer=1-5 (or 1/3/5) or in OSM syntax 1;3;5



>   The more so when that same
> information is on coincident polygons that iD makes hard to
> manipulate, or even notice.
>


let's not discuss the problems of individual software solutions, they will
adapt sooner or later. When there are polygons with coincident information,
there is not issue, when they are different, it may indicate either a data
problem (error) or the node tags will override the polygon defaults. It is
not completely clear, both interpretations are around.


> it could also be seen useful redundancy that strengthens the stability (if
>> you have verified the address information for the business, even if someone
>> "adjusts" the positions of the buildings and oversees the POIs, you will
>> still have the correct address on the POI.
>>
>
> But there are cases where using a node rather than a building (not just an
> area but a building=*) for a POI means the name doesn't get rendered.
> Clubs
> and crafts, for example.
>


it doesn't matter, as it is just refering to a single piece of rendering
software. Everybody can display any name they like.



>
>
>> I.e. explicit tagging is more reliable, and can be seen as a confirmation
>> that the information has been actually verified, compared to a POI without
>> addressing information lying inside a given address boundary (think about
>> someone placing a POI by memory roughly where it should be).
>>
>
> That's just another reason why people tag the same object as both a
> building
> and a business rather than making it two objects.  It makes clear that
> there is
> a relationship between the two rather than it possibly being an accident.
>


problem is that the kind of relationship they are modelling (identity) is
incorrect.



> Each approach has benefits in certain situations.  I don't think any of
> them
> deserve the "You must not do it that way" injunctions we sometimes see
> here.
>


+1

Cheers
Martin
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