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

Kevin Kenny kevin.b.kenny+osm at gmail.com
Fri Jul 27 17:48:51 UTC 2018


I'm all for SI units for things like voltages and elevations. I'm
perfectly fine with tagging the elevation of Slide Mountain as 1274
metres and letting a US data consumer convert that to 4180 feet.

Regulatory things like maxspeed=* should have the unit in the tag, and
they should be in the same units that the signs are in. A sign reading
'Speed limit 25 mph' means 25 mph, and entering 40.2336 km/h loses the
information that the regulatory signs are in US customary units.

Data consumers have to deal with that stuff now - and it's not that
difficult,. I've done software that consumes OSM data, and unit
conversion was a much lesser headache than a lot of other tagging
issues.
On Fri, Jul 27, 2018 at 1:31 PM marc marc <marc_marc_irc at hotmail.com> wrote:
>
> Le 27. 07. 18 à 18:51, Richard Welty a écrit :
> > but practically it's probably not a good idea in mapping, where i think
> > we should be using local units in an unambiguous manner.
>
> nothing prevent a editor nor a site to show "volt" next to the textbox
> for voltage value nor to show "km/h or mph" next to the textbox for
> maxspeed depending of the location.
> it only needed to have something to tell data user if a tag have only
> one unit or if the unit varies according to location (in this case, we
> need again a schema to store default value (in this case unit) somewhere
> with a link with osm location).
>
> Le 27. 07. 18 à 18:52, Philip Barnes a écrit :
>  > On 27/07/2018 16:20, marc marc wrote:
>  >> I agree maybe with the exeption of case like maxspeed
>  > And maxheight and maxwidth.
>
> I agree that it'll be easy to not include those tag, at least to start.
> it's why voltage is a very good usecase to start with it :)
>
> >
> > On 7/27/18 11:20 AM, marc marc wrote:
> >> I agree maybe with the exeption of case like maxspeed
> >>
> >> François voltage is a good usecase to open an issue to the whised app.
> >>
> >> Le 27. 07. 18 à 14:19, Andrew Hain a écrit :
> >>> My own preference is to have no (zero) units in the database, decimals
> >>> where wanted (maxwidth=2.2) and unit management support in editors.
> >>>
> >>> --
> >>> Andrew
> >>> ------------------------------------------------------------------------
> >>> *From:* Warin <61sundowner at gmail.com>
> >>> *Sent:* 27 July 2018 12:27:04
> >>> *To:* tagging at openstreetmap.org
> >>> *Subject:* Re: [Tagging] Let's get (quite) rid of units and their
> >>> multiples in OSM values
> >>> On 27/07/18 21:11, Martin Koppenhoefer wrote:
> >>>> sent from a phone
> >>>>
> >>>>> On 26. Jul 2018, at 21:26, François Lacombe <fl.infosreseaux at gmail.com> wrote:
> >>>>>
> >>>>> I don't want to break things but only improve them, all the best
> >>>> one issue with using only one unit for a tag is that they can’t always be transformed without rounding. E.g. maxspeed=55mph cannot be converted to kph without losing information
> >>>>
> >>>> Also, shorter notations are better readable, hence reduce the likeliness of errors not noted.
> >>>>
> >>>> On the other hand, I agree in the example of voltage it would make it easier for queries to use the same unit. (you still can make queries, but they are more complicated if you have to take units into account)
> >>>>
> >>>>
> >>> Unfortunately not everyone uses the same units... heights are in meters,
> >>> feet .. depending on where you come from or what activity you follow.
> >>>
> >>> Voltages are in volts so the same units... but multiplies are common for
> >>> high voltages .. no one uses 33000 volts .. they all use 33 kv.
> >>> If you stipulate that all voltages have to be in kv then 115 v becomes
> >>> 0.115 kv, 240 v becomes 0.24 kv and 415 v becomes 0.415 kv ..
> >>> that is not how people talk about these things.
> >>>
> >>>
> >>>
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> >>
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