[Tagging] one feature one element

Warin 61sundowner at gmail.com
Sat Jul 6 03:17:48 UTC 2019

On 05/07/19 19:57, Mariusz wrote:
> On 05.07.2019 07:05, Joseph Eisenberg wrote:
>> I've removed this statement from the page because it leads to
>> ambiguous data and directly contradicts the One feature per one
>> element rule
>> [Examples of bad situations:] "An area object representing a
>> single-use building with a point object inside it. Move the tags to
>> the area object and delete the point."
> This is common and widly accepted practice. Don't try to change 
> mappers behaviour by editing wiki.
> Also, there is no contradiction.  From wiki: "It means one 
> on-the-ground real world feature should be mapped with only one OSM 
> element. " That it - no multiple osm objects for one real world feature.
> It is fine to map multiple real objects with one osm element, 
> especially if you don't have enough data to map them seperately.

I have done both - mapped a shop on the building way and in a different 
place, as a node inside a building way.

The advantages of having the shop as a node inside a building way .. if 
the shop moves it is much easier to move the node and the history is 
retained. I think I prefer the shop as a node  method in hind sight. 
Much easier to maintain.

>> If the same feature is tagged with building=* and another feature like
>> shop=* or office=*, it's ambiguous whether other tags like name=*
>> represent the building itself or the other feature.
> Nothing new, this problem already existed with roads and bridges and 
> was fixed by putting bridge name into bridge:name tag.
>> While it's common to tag single-use buildings in this way, it isn't
>> the best practice, because of this ambiguity. Users should not be
>> encouraged to delete all single node objects within buildings without
>> carefully considering each of the tags.
> That's true. POI and building may have more identical tags, for 
> example "start_date" or "operator".
> Moreover, you recently edited many times 
> https://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element and 
> some newly introduced things are controversial:
> *"Ideally, every OSM element or object should be tagged with only one 
> main feature tag, to represent a single on-the-ground feature."
> I've never heard of such rule. It doesn't seemed to be correct. It is 
> against KISS principle and it is not how mappers map.
> For example, there is nothing wrong in placing tags 
> "landuse=industrial + barrier=fence" on one osm way. Doing it as 2 
> ways would even give you a warning in JOSM (ways in the same position).

Some possible issues with that?
The fence is usually inside the boundaries of the land use.
The fence will have at least gates.
The fence may not be of a consistent height/construction ..

> *"For example, use the feature leisure=picnic_site with the property 
> tag drinking_water=yes, instead of using the separate feature tag 
> amenity=drinking_water on the same node or area."
> This example is a bad idea and mappers shouldn't be encouraged to do 
> so. amenity=drinking_water is far more popular tag and replacing it 
> with drinking_water=yes may hurt data consumers.

I don't think it is an issue of replacing it. But where the location of 
the drinking water is unknown?

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