[Tagging] MAST RELATION

[Tobias Knerr]

On 07.03.25 at 18:55, Christian Müller wrote via Tagging:
> 
>> EACH ELEMENT SHOULD BE TAGGED AS A NODE WHERE THEY ARE IN THE WORLD, EVEN IF
>> THAT MEANS OVERLAPPING NODES.
> 
>  From a data organization point this is a bad idea, because
> 
> a) the same information (lat/lon) is stored multiple times
> needlessly

I disagree. It is useful that objects are represented as nodes even if 
they are attached to something.

One reason is that far more data consumers will care about, say, finding 
or rendering waste baskets than care about what they are attached to. 
And if they are nodes, then those "attached" waste baskets can be 
treated just the same as stand-alone waste baskets.
Of course, another reason is that many mappers find relations hard to 
work with.

As for the data organization angle: If multiple objects do in fact have 
the same horizontal position, then having a lat/lon pair in our database 
multiple times seems completely fine to me. It is not any more of a 
conceptual issue than all objects with the same height having the same 
height value, or all objects with the same color having the same color 
value.

> b) the position of the pole does not change with the attach-
> ments and most people will understand pole+attachments as
> a single object and one of osm's conventions is:  one
> object on ground should match (exactly) one object in the
> database

What constitues an "object" is of course somewhat arbitrary. Some 
examples (such as a group of traffic signs) could plausibly be 
considered a single object. But for many other examples, I find that 
odd. If I attach a billboard or a camera to a street lamp, it doesn't 
cease to be an object with its own distinct set of attributes. It has a 
different color and material, looks in a different direction, and so on.