[Talk-GB] Pubs as areas: should be map the property or the building?

SK53 sk53.osm at gmail.com
Fri Mar 11 17:26:40 UTC 2016


Earlier today browsing Pascal Neis summary of changesets I noticed a
comment about reverting a duplicate pub node, and glanced at the changeset
<http://www.openstreetmap.org/changeset/37749403>.

The pub had indeed been added again (and subsequently removed). However
what caught my attention was that the amenity=pub tag had been applied to
the entire area of the pub grounds (car park, buildings etc.). A quick
query on IRC and Andy (SomeoneElse) also maps pubs this way, however rarely
with as much detail as this particular one. The general alternative is to
map pubs as areas on the building of the pub.

The obvious advantages of mapping the entire area of the pub property are
largely to do with the immediate association of car parks, beer gardens,
children's playgrounds with the pub and thus ready interpretation of things
like access tags and resolution as to which car park belongs to the pub.
This approach is clearly less cumbersome than using a relation, such as
associatedCarpark (invented I believe by Gregory Williams in Kent).

The disadvantages, at least to my mind, are:

   - Non-intuitive. Certainly I have never thought of mapping pubs this
   way, although I can see the point. I doubt that a newcomer to OSM would
   find this the straightforwardly obvious approach.
   - Pubs are licensed premises. The premises licensed usually relate to
   the building.
   - Where do we place tags associated with the pub premises which may
   apply also to other parts of the pub property (an obvious one would be
   opening_hours).
   - Peculiar rendering. In this case a pub icon in a car park. Even if we
   fully accept "not tagging for the renderer", let's consider how we can tell
   renderers to improve icon placement. Andy suggested on IRC a label node,
   but this implies a relation: do we want to replace a simple node &/or area
   tag with a node, an area & a relation? And then ask the Carto-CSS team to
   deal with it? It seems to me that this pushes the bar too high not just for
   inexperienced mappers but also those of us who have been at it for a while.
   In the meantime the CartoCSS rendering will look rather daft in such cases.
   - Consistency. In general pubs will get mapped initially as nodes over
   the pub building, and attributes on a node easily transfer to a building
   outline + (usually) building=pub. In particular the node & area centroid
   will tend to be very close. Thus the two different ways of mapping relate
   to each other in a clear way.

This issue of course is more general than pubs. For instance we map
schools, colleges, universities and hospitals as areas and place all the
relevant tags on the area. Churches & other places of worship, on the other
hand, tend to have the amenity tag placed on the building. (This makes
sense as in many cases it is the building which is the place of worship not
the grounds). Also, I certainly will map a supermarket as the building
rather than the whole area including car parks, petrol stations etc.

Obviously I prefer for supermarkets, places of worship and pubs that the
area mapped should be the building. However I can equally see that there
are certain issues which are otherwise intractable where mapping the whole
area offers some advantages.

One approach which would reflect my own mapping approach would be to tag
the complete area associated with the pub as landuse=retail, with a tag
such as retail=pub. This would require no more additional OSM elements than
used at the moment, and would provide for the identification of
associations with car parks etc (and would work fine with multipolygons for
pubs where the car park is across the road or otherwise removed from the
pub.

This is an example of how as more stuff gets mapped different styles
evolve. Neither is specifically wrong or right, but it would be nice if we
could find a consistent style which satisfies most needs.

Cheers,

Jerry
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