On Tue, Sep 2, 2008 at 1:02 PM, Dave Stubbs <[EMAIL PROTECTED]>wrote:
> On Tue, Sep 2, 2008 at 11:08 AM, spaetz <[EMAIL PROTECTED]> wrote: > > On Tue, Sep 02, 2008 at 10:08:11AM +0100, Dave Stubbs wrote: > > > >> I think we had this discussion before and came to the conclusion that: > >> - 50mph was essentially mapping a sign, because the speed limit is a > >> speed, not a unit ... > > > > And as some applications might want to show the precise sign value, not > some rounded appoximation (agreed that apps can round). > > I've never seen a speed sign for anything but integer units. Given the > accuracy of most speed measuring devices I'm guessing I never will > either. Here's one: http://carcino.gen.nz/images/index.php/5922d576/48b0f367 > People rarely set speed limits at anything other than > divisions of 5 units be that mph or kph, unless the result is actually > a conversion. ie: the speed limit in Windsor Great Park is signed as > 38mph. So if I convert 112kph to mph, and round... the result is not > an approximation, but the actual signed speed limit. This is one of > those know your domain things. > > > Plus it's more intuitive for the mapper. > > Agreed. > > > > > >> - that the tag without a unit should probably be assumed to be km/h. > > > > that's why my example used maxspeed=50mph and maxspeedd:mph=50 in case > you haven't noticed :-) > > > >> - that anything intelligent enough to know if it wants to represent > >> maxspeeds in mph/kph is intelligent enough to know it can safely round > >> to the nearest integer. > > > > Anything being able to round to the next number should als be able to > read miles (or have a clever enough preprocessor to do it :-)) > > > >> - and that it's possible to represent an exact mph in kph anyway if > >> you can really be bothered: 1mile == 1.609344km exactly > > > > Do you always carry your calculator with you when mapping or do you do it > by hand :-) > > > > I am not saying that it shouldn't be tagged as a rounded km/h value. > However, people shouldn't think they are forced to. If they feel that > maxspeed:mph=50 makes more sense, than that should work too. > > > > I'm actually just summarising the mess that the last time this > discussion came up, where I was actually arguing the mph case. > http://lists.openstreetmap.org/pipermail/talk-gb/2007-September/002417.html > > About half of the arguments are a little weird, not least the whole > rounding thing, which it turns out really isn't a problem in any > sensible application. > > Dave > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk >
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