... d'accord! My only puzzle now is to wonder why I am e-mailing an Italian about speed limits - didn't think you had them in "la bella Italia" - strange thing is the only ticket I have ever had was in the USA ...
... And don't you just love those crazy speed limit pictures that got posted in this thread! Ciao! Mike Harris -----Original Message----- From: Fabrizio Carrai [mailto:[email protected]] Sent: 08 May 2009 13:46 To: [email protected] Subject: [OSM-newbies] R: R: Road Maximum speed in UK units Because you forget ""When in Rome, do as the Romans" (you teached!! ;-) ) While we are having fun, we also addressed a more serious subject: Render max speed limits, according to WHERE you are and if and what speed reference you need or you have. On the contrary of you, when I'm in USA I want that my navigator alert me in mph (and not in unuseful km/h). In UK, I have no problem: I avoid to drive on the "wrong" side of the road ;-) ! Ciao! Fabrizio > -----Messaggio originale----- > Da: [email protected] > [mailto:[email protected]]per conto di Mike Harris > Inviato: venerdi 8 maggio 2009 13.56 > A: [email protected] > Oggetto: Re: [OSM-newbies] R: Road Maximum speed in UK units > > > Personally, when stopped for speeding on the Continent, I pretend to > speak > (only) English and claim that I thought the sign meant mph - this does > not usually work - I can't understand why not (;>) ... > > Mike Harris > > -----Original Message----- > From: Fabrizio Carrai [mailto:[email protected]] > Sent: 07 May 2009 16:19 > To: [email protected] > Subject: [OSM-newbies] R: Road Maximum speed in UK units > > > > > -----Messaggio originale----- > > Da: [email protected] > > [mailto:[email protected]]per conto di Thomas König > > Inviato: giovedi 7 maggio 2009 11.12 > > A: [email protected] > > Oggetto: Re: [OSM-newbies] Road Maximum speed in UK units > > > > > > 1) Only for clarification: hour is NOT an SI-unit. So when measuring > > in km/h we can't complain about the ridiculous unit system in the US/UK. > > You are right, but just to give a rationale to what we are > doing: [1] says: > > "The SI base unit for time is the SI second. From the second, larger > units such as the minute, hour and day are defined, though they are > "non-SI" units because they do not use the decimal system, and also > because of the occasional need for a leap second. They are, however, > officially accepted for use with the International System" > > More info in [2]. I think that this should support the continuation of > the use of "hours" as time unit. > > > > > 2) I think it shouldn't be too hard for a computer to convert units! > > (Regardless of the fact if someone uses kph, kmh, k.p.h. or whatever > > abreviation.) Isn't that what computers are made for - calculations? > > Regarding the loss of accuracy: As speed limits are always integers > > (and I guess all over the world they should be divisible by 5) the > > computer > > (renderer) should be able to perform the conversion without loss of > > accuracy! > > > > Computer are built to compute, but we cannot abuse of it! > Computing power is > a limited resource and we shoudn't waste it doing extra calculations. > > Things change day-by-day, but mobile devices are still less powerful > than the desktop PCs. > I think that all of you agree that we (as OSM mappers) often act as > "Data designer". Although the "Data Designer" objectives are different > than the "Application Designers" we cannot avoid to think to the use > of our product. > That means that our "product" must be "usable" in the best efficent way. > > The reason of the discussion is to find the best way to tag the speed > limits avoiding extra effort during their use. > > So , my personal propose would be: > > a) Let the mappers to use their own units > b) Set the requirements for the application to convert all such data > according to well know function to a SI (or an accepted unit). e.g. > meters for distances, km/hours for speeds > > Point a) is "justified" by the fact we want to map the reality and the > reality is that in saxon countries the signals are in Mph. As Mike > said ""When in Rome, do as the Romans" ! > Of course that strongly simplifies the job for the UK mappers, with > the request to add the info that explicit the unit. [4] indicates that > there is still a certain standardization. I don't know if this is the > best solution for a data processing application. > We have also to say that this is still in compliant with the wiki [3] > "UK mappers will often include units in the maxspeed tag, ie: > maxspeed=20 mph (miles per hour)". > A more literally aderence to the standard, i.e. > "value"-space-[unit], could > support the string tokenizer function (many of them require a > separating character). > > In my opinion that's not a detail. Think to a routing application that > load the speed limit indications and has to check if a unit has been > specified and do the proper conversion all the time. This operation > should have to be do done on each speed value that is in a tag!. > > Point b) limits the action in point a). Only standardized units should > be specified, since the application shall rely on the list of the standard. > Still free to add "furlongs per fortnight" as unit, just specify the > converting function to SI in the wiki. > > > Ciao! > Fabrizio > > > [1] http://en.wikipedia.org/wiki/Time > [2] http://physics.nist.gov/cuu/Units/outside.html > [3] http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed > [4] http://tagwatch.stoecker.eu/Great_britain/En/tags.html > > > > > > _______________________________________________ > newbies mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/newbies > > Nessun virus nel messaggio in arrivo. > Controllato da AVG - www.avg.com > Versione: 8.5.325 / Database dei virus: 270.12.21/2103 - Data di > rilascio: 05/07/09 18:05:00 > _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
