Yes, this is kind of tagging for the renderer however I believe there are some legitimate technical reasons why it is needed - specifically with administrative boundaries. The first thing that comes to mind is that while rendering based on outlines seems nice, the centroid of a city/country is not always where the label needs to be put. Take the USA for example. If you compute the centroid of the entire boundary relation, Hawaii and Alaska are going to pull it to the northwest and you will end up with a label that is not in Kansas where it belongs. I suppose you could usually just use the largest contiguous area to compute centroids for labels but it is a complicated matter. And even then, it would diverge from what people expect in many situations. Most maps put city labels in the social or economic center of the city, not the centroid of the outline. In my city the centroid would probably put the label in or near the university campus which would be awkward on a map.
What has been done in a lot of situations is adding the node to the relation with a role of "label" as an explicit rendering hint. In theory the node would not need to be tagged with duplicate name/place information if it is part of the relation but of course before any such change could happen, tools would need to change first otherwise all city labels on osm.org would vanish. I am curious about your statement about names being rendered multiple times. The only time I have seen this is with multipolygon relations. And on Cyclemap where city labels *are* rendered based on the outlines instead of the nodes. City exclaves each generate their own label which leads to decidedly sub-optimal renderings like this: http://www.openstreetmap.org/?lat=38.8226&lon=-97.617&zoom=12&layers=C Toby On Wed, May 29, 2013 at 7:54 PM, Jakub <j...@kub.cz> wrote: > I do not want to sound too radical, but it is quite astonishing, how *Good > practices <http://wiki.openstreetmap.org/wiki/Good_practice> can sometime > radically differ from apparently widely accepted and even promoted usage.*Let > me point out an example of what I mean, but I beleive that the problem > is much wider than this particular case: > > *Countries on nodes vs areas vs relations* > > On one hand there is a: > > - widely used practice to map country *both as node and relation* (and > sometimes area) > - suggestion that the place=country should be placed on node see > Place<http://wiki.openstreetmap.org/wiki/Place> > - suggestion that > Key:place<http://wiki.openstreetmap.org/wiki/Key:place>should be used on node > or area (relation not mentioned) > - suggestion to > > and on the other hand there is a: > > - Principle Don't map for the > renderer<http://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer>- which > is clearly violated by tagging node as a country, because country > is not a node and in fact this node is only ment for renderer (supported by > giving this node a label role in country relation) > - Principle One feature, one OSM > element<http://wiki.openstreetmap.org/wiki/One_feature,_one_OSM_element>- > which is clearly violated by fact that the tags are repeated both on node > and realtion (or area). This practice is not only used it is also > encouraged by wiki pages. > > Now, please do not get me wrong, I might be wrong and there might be some > reason for that. If there is one, I would like to correct the documentation > and rewrite Good practices (or list exceptions to them). If there is no > reason I would like to clan up the data, but surely there should be some > consensus on that and the consensus should be very well documented so there > is not confusion in the future. > > Thanks for help > > Jakub > > PS: I beleive that this problem is much more general, it is also true with > all sorts of regions, cities and villages. Names are rendered two or three > times and is not good at all. > > > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk > >
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