[OSM-talk] Applicability of wiki tagging and votes: may, should or must

[Mateusz Konieczny]

On Fri, 29 Jan 2016 19:38:46 +0100
Roland Olbricht <roland.olbricht at gmx.de> wrote:

>  >> This diversity of tagging is often quoted as a problem for data
>  >> consumers. Oddly, this is often by people who don't actually use
>  >> the data but feel it must be awkward. Actually it's not. All OSM
>  >> data has to processed before use. This processing can be fairly
>  >> straightforward or really complex, but that's not much to do with
>  >> tagging diversity. Whatever the processing is (LUA code, SQL code
>  >> or any other coding) it only has to written once and can be used
>  >> over and over again.
>  >
>  > "but that's not much to do with tagging diversity" - I would
>  > dispute it, from my personal experience. Tagging diversity IS one
>  > of real problems in using OSM data.
> 
> Could you please give an example?

My first ever attempt to display cycleways went as follows:

- display ways tagged as highway=cycleway

Why nearly everything is missing? OK, there is also bicycle=designated

- display also bicycle=designated

Failed due to people adding vehicle=designated, bicycle=designated,
horse=designated etc to a normal roads (rare, but enough to result in
noticeable errors)

- replace bicycle=designated by [highway=path; bicycle=designated]

Later I also discovered that [highway=footway; bicycle=designated]
combination also appears (due to
https://github.com/openstreetmap/iD/issues/2327 ).

That would be OK. But it is not going to work properly. There are
still cycleway=track ways. Also, [highway=bridleway +
bicycle=designated]. Some people decided that inventing
bicycle=official makes sense - and to handle it at least
[highway=path; bicycle=official] and [highway=footway;
bicycle=official] and [highway=bridleway; bicycle=official] would be
necessary.

There are more accepted in at least some region methods to map
cycleways and even more rare methods. For example tagging joined
footway + cycleway as [highway=footway; cycleway=lane].

There are many places where my map style would fail, as it
would be unable to interpret local tagging scheme.

Remapping/retagging my city was very significant part of this map
project. In the end about 1/2 of work was adding new data, 1/4 editing
data to fit common tagging schemes and creating transformations to
handle tagging complexity and 1/4 was making map style.

For reference - this project is a horrible mix of Maperitive
and Ruby scripts and at least currently resides at
https://github.com/matkoniecz/bicycle_map_of_Krakow ).


I am not claiming that there are quick & easy ways to reduce complexity
- but complexity has some real negative consequences.

> If you ask people to misrepresent the reality to fit a fixed tagging 
> scheme

That is clearly not OK, nobody advocates misrepresenting reality.