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The Wiki descriptions in English and German do not seem to be precise for me. ID in German is clearly stating it should be one half of the building, StreetComplete seems to state it should be the whole building. Should we have a discussion for clarification about it, or has this been done and I just did not understand it right? :) |
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As with many OSM tags building=semidetached_house can be used in both cases. It is not uncommon to map pairs of houses as a single building in a first pass only splitting them later. One can infer that a building with semidetached_house which is unconnected to another building most likely represents 2 addresses (it is not inconceivable that one of the pair might have been destroyed, for instance by bombing), equally if two contiguous buildings are both tagged semidetached_house they can be merged and treated as a unit if desired. Note that in general building=house is not a particularly good tag. As described on the wiki it seems remarkably specific for wealthier North Americans & Europeans. Around the world a standard family house is likely to be far more variable than the implied detached house of first world urban suburbia. However, many building tags are probably best used in a local (national) context where specific widely used typologies will be familiar to most people. |
The Wiki definition seems fairly clear to me. It's a part of a house that shares one wall (at least two shared nodes) with the other part. I don't think the word "half" in the general description means 50% but rather one part of a two-part building.
That said, I've never used this tag. I mostly map houses via satellite imagery so cannot know the details of their construction.
Yes, on its own, I would understand the Wiki definition that way, too. Given it is meant like that, it could just be better, if it would explicitly state, that the tag should not be used for the complete object. So maybe it is only StreetComplete, which is seemingly on a wrong wording? If someone confirms my interpretation, I would ask them / raise a request to clarify it.
From a data consumption point of view, you would probably assume that two houses stuck together are semidetatched houses regardless of tagging and that an unconnected building tagged as a semidetatched house must contain two residences side by side.
Two joined ways tagged as
semidetatched_housemust also be treated as tagging the individual houses or you have 4 houses and thus a mistagging.As with
building=terraceI see little benefit to this tag unless it is on the overall outline, as if the individual residence is tagged, you may as well use=houseand count the number of joined houses to see if it is a duplex/triplex/terrace.I started a Discussion at https://wiki.openstreetmap.org/wiki/Talk:Tag:building%3Dsemidetached_house#is_this_for_half_the_building_or_the_whole_building.3F - Opinions welcome.