[Tagging] building = house vs detached.

[Martin Koppenhoefer]

sent from a phone

> On 25. Jul 2018, at 00:11, Colin Smale <colin.smale at xs4all.nl> wrote:
> 
> But we must also not be tempted to force multiple concepts into a single tag hierarchy. Before we start down that path, let us be clear what the hierarchy is intended to represent, and what factors are in-scope (a different brick colour will not lead to a different building type, but brick-built vs. wood-faced may impact the type).


I was mainly thinking about offering a possible structure for the tags that are used now (most usage). It would hopefully grow with the help of many mappers. Overlaps and orthogonal classes can be discussed when we find them. For rough classes like those that are mostly used, there is usually no material implied (material can be tagged separately anyway).



> Lets be explicit about whether it is as-built or as-used, and how to handle mixed-use buildings.


These are both very good questions. Generally the type is as-built, but this includes transformations. If something was built as a water tower (extreme example) and now there are apartments in it, how do we classify it. The answer is probably in judging the single case. Does it still look like a water tower with apartments in, or is it not recognizable any more? Mostly I would tend to use the original purpose, which imposed the requirements that made the building what it is (unless drastical modifications were applied later on). 


For mixed use buildings: these could be types of their own. While mathematically there could be near infinite combinations, in practice there are not so many. There are surely also a handful of weird/unexpected combinations, but for these you’ll have problems with any system anyway, let’s not get them into the way of finding something for typical combinations (e.g. from bottom to top, all are optional, shops-offices-apartments). I’d treat shops and restaurants/pubs/cafes the same here.
A different approach would be splitting into building_part of blocks of building levels with the same structure and add level tags




> If we look first at as-built, we will need a parallel tagging taxonomy for the usage aspect; and the other way around of course.


Usage is already tagged as POIs, if you map them as areas and add level tags you are done. (Do we need tags for residential units?)


Cheers,
Martin