[Tagging] Let's get (quite) rid of units and their multiples in OSM values

Eric Gillet gill3t.3ric+osm at gmail.com
Sat Jul 28 09:14:09 UTC 2018

I agree with François and Marc.

Le ven. 27 juil. 2018 à 13:28, Warin <61sundowner at gmail.com> a écrit :

> Unfortunately not everyone uses the same units... heights are in meters,
> feet .. depending on where you come from or what activity you follow.

You're right, but as OSM is an international database, standardizing data
(meaning units too) is a must. Just like phone numbers where although local
residents usually don't use ITU prefixes (+XX), phones numbers should be
entered with those prefixes to ensure valid usage for consumers.

Le ven. 27 juil. 2018 à 21:21, Paul Allen <pla16021 at gmail.com> a écrit :

> If you're navigating somewhere unfamiliar to you and GPS isn't giving you
> an
> accurate signal, what you're interested in is what signs actually *say.*
> Because
> when you're in confusing territory a speed sign, or a bridge clearance, or
> whatever
> may be a significant clue.  Knowing that the speed limit is 40.2336 km/h
> doesn't tell
> you to look for a sign saying 25 mph.

Most GPS/routing applications (including OSMAnd, Google maps) already
convert maxspeeds to user's prefered unit. I do not remember ever seeing a
fractional legal speed, so by rounding the value you can obtain the sign
value with good confidence.
Another thought : Even if maxspeed=* on highway=* could be in kph,
traffic_signs could still be mapped with local, explicit or implicit units.
That would solve both problem.

Le ven. 27 juil. 2018 à 22:22, Tobias Knerr <osm at tobias-knerr.de> a écrit :

> I currently prefer explicit units in the database because they document
> the mapper's intent and avoid ambiguity.
> Defaults aren't always obvious. For example, people mapping pipelines
> have documented millimetres as the default for diameter=*, but it seems
> tree mappers haven't gotten the memo and (reasonably) assume it's
> defaulting to metres like height=*, width=* or circumference=*.

An unit selector can be implemented in editors quite easily. StreetComplete
already does work with different units for example.
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