On Thu, 26 Sep 2019 at 00:53, Warin <[email protected]> wrote: disused:*=* means it cannot presently be used for its intended purpose. > That does not mean it does not exist. >
Correct. How renders chose to display that is up to them. > Also correct (sadly). But the tagging is correct and truthful. > Using disused=yes is correct and truthful. Using disused:foo=bar is ALSO correct and truthful. Both are documented as valid ways of tagging disused objects. > Choosing another tag because it renders the way desired is not a good > thing. > Only because the behaviour is not guaranteed across renderers or even over time for a single renderer. However, choosing one correct and truthful tag over an alternative correct and truthful tag because of how it renders in one renderer is not wrong (even though some may consider it unwise). For those who use disused=yes because it renders .. are you equally happy > to have amenity=toilet rendered when it has disused=yes on it??? > How about a pub, atm etc etc... > You mean like the toilet near me that has been shut down because the council can't afford to run it but which a local non-profit organization hopes to take over and re-open? The building still exists, but if i use disused:building=yes it vanishes from standard carto. It's no longer being used as a toilet but may be in the future, but if I add disused=yes then the toilet symbol renders so people turning up there with full bladders are going to be upset. Or how about the many disused quarries near me? They still exist. They are visible. Some of them pose a hazard. If I use disused:landuse=quarry they vanish from standard carto. Renders need to distinguish between active features and those no longer in > service, but still existing. That is a rendering issue not a tagging issue. > How could renderers tell the difference unless the tagging informs them? One way would be for them to render only physical objects in the disused namespace, so that building:disused=yes renders but disused:amenity=toilets does not get a toilet symbol. That leaves a problem if somebody uses building=yes + amenity=toilets + disused=yes, although that's still possible for a renderer to figure out. However, many renderers do not currently make those distinctions. The other way is that renderers agree to support a tagging convention that disused:foo=bar suppresses rendering but disused=yes does not (standard carto is ahead of the game here). There ARE cases where disused objects should be rendered and there ARE cases where they should not. We SHOULD have a tagging convention that at least one major renderer supports so that we can control this. Mostly it seems that disused physical objects should render but disused properties should not, although that may not always be the case, so two ways of tagging disused objects leaves the decision up to the mapper rather than relying on a heuristic that may sometimes be wrong. Moaning that we have two tags used to do the same thing which mappers choose between because of rendering isn't helpful. Warning that those choices may be incorrect in different renderers, or may suddenly stop behaving in the expected way in standard carto is better. A documented agreement with (at least standard) carto on expected behaviour that allows disused objects to be rendered correctly would be best of all. Except this is OSM and we don't do joined-up thinking. -- Paul
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