[OSM-talk] Mapping canals

[Gervase Markham]

Abigail Brady wrote:
> I've tagged low bridges in Leicester with maxheight=15'0", for example.  
> That's what the sign on the bridge says, that should be represented in 
> the database.

I definitely think that's wrong. Even if we decide to have units in the 
database, that does not mean we need to allow all of <15'0">, <15ft 
0in>, <15 feet 0 inches> and so on. The info in the database is not and 
should not be designed to be rendered directly, either on maps or in 
routing software, and so does not have to correspond to what's written 
on the sign. If the database says "30mph", that might be rendered as 
"30", or as a white circle with a red border with a "30" in it, or even 
as the same with a "50" in it, if the person using the software or map 
wants km/h.

> We need for the UK to keep imperial measurements in the DB.  Now, I 
> abhor imperial measurements and want to see us completely metricated, so 
> please don't mistake me for some kind of rabid anti-metric person.  But 
> the signs say things in feet and inches and that is a fact.  This 
> discussion should not be about a bunch of non-UK people declaring that 
> UK people aren't allowed to use the unit system the UK (regrettably) 
> uses in the database, 

I'm a UK person, and (at least up to now) I've been declaring that UK 
people shouldn't be allowed to use the unit system the UK uses. :-)

> There are many options.  I think defining a very small set of allowed 
> units and formats thereof, and then sample code in many languages to 
> convert these to metres/kilograms, might be the solution.

That might work. But then, don't you lose some of the flexibility that 
the "put the units into the DB" crowd are asking for? As has been shown, 
there's no loss of precision in going all-metric, at least with lengths, 
because 1 inch is exactly 2.54cm.

Gerv