I'm thinking of proposing a new feature, which I haven't found a reference to on OSM wiki.
The proposal concerns minor buildings on a residential property - sheds, garages, playhouses, etc. There does already exist well established tags for specific building functions, like building=shed and building=garage. However it's often difficult to reliably discern the function of a small building from the aerial imagery. Rather than spending time to analyze the image, and making a guess of what the building is, it'd be more useful just to tag what's realiably known from the image. And what's clearly known is that they are less significant buildings than the main house on the same property, no matter whatever their actual function happens to be.
So, tagging these minor buildings differently from the "major" buildings would be useful, even in cases where it's not known what exact type that minor building is. For example that information could be potentially be used in rendering, drawing such buildings as bit less prominent, like building=house are currently less prominent compared to the generic building=yes. (I realize rendering changes are unlikely to happen, but I'm talking in principle here.)
My question concerns whether it would be better to:
1) propose a very general purpose tag, such as "building=minor" that could be used refer to any building that is always conceptually in relation to a "main" building of a site, but of significantly minor significance. This could then be used in any context where one building is the prominent one, e.g. with a factory that has minor buildings (of unknown function, maybe storage) nearby.
2) propose a more specific tag for the purpose, such as "building=residential_property" or "building=residential_minor"
3) not propose any new tag, but rather just use building=residential, even though that doesn't convey the minor significance of the building. (To show the difference: building=residential could just as well be used to tag the main house on the property, but the new building=minor could not bo (correctly) used to tag that.)
I'm inclined to think the first option would be best.
The only reference to such a feature I've found is a question on this forum: "How to tag residential properties garages, sheds etc?" I haven't found any similar feature in use from taginfo.
(And yes, I realize because of the wiki nature I can start using pretty much any tag I want without proposing them, but I wanted to ask which more experienced mappers would consider to be the best approach in this case.)
You mention taginfo, which already has over 3000 building=shed, over 155,000 building=garage (and over 72,000 building=garages). Garage and garages already render less prominently (as building=house and building=residential do). If you want building=shed to render similarly then I think trac is the place to request it.
answered 07 Feb '12, 07:18
If you do not have enough information to tell what kind of building it is but still "know" that it's a "minor" building then how do you know it ?
My guess is that 99% of the time you know because that building is smaller than the nearby ones. If building size is your source of information, then you might as well not do any "vague tagging" and let the renderer/analyzer use the already-available size information directly ?
answered 07 Feb '12, 13:32
Vincent de P... ♦
In some countries, these minor residential builidings are collectively known as "out buildings". One solution for these unidentified "minor residential buildings" is to create a new tag scheme: building=out_building out_building=shed/garage/playhouse/gazebo/*
alternatively, use building=out_building when the type is unknown and building=shed/garage/playhouse/gazebo/* when it is known.
answered 23 Sep '13, 06:46
The general idea is that the building is tagged building=yes because the mapper has identified a feature on the imagery that conforms to that of a structure of unknown usage. Once you start tagging a feature as something more specific such as shed or outhouse then subsequent mappers assume that tag is there because someone has identified that structure and knows it's use and has classified it as such. In your suggestion this is not the case, you want to "guess" the status of the structure without factual or local knowledge and this would be misleading to subsequent mappers. A smaller structure on a residential property could be a garage ...but could just as easily be a garage converted to a granny flat. A large structure tagged building=yes and a cluster of smaller structures around it also tagged buildings=yes will speak for itself without conveying any specific usage of those structures. The intelligent algorithm will have been designed around local averages (i.e. a residence consists of one main building, one garage, one/two/three "other" usage buildings, and may even have an addition of say 1 in 5 may have a granny flat) so while size does matter, guessing does not.
answered 19 hours ago
I think this query has some merit and should result in a debate on the proposed features page. What I would suggest, however, is something like this:
Keep building:yes as the main tag and allow:
It is as you say a wiki and if someone wants such detail in the area of his/her interest then so be it. Such detail could be rendered "as you like it" whereby the general mapnik renderer would stay the same. Or something like that!