If we look how other units are treated in OSM (http://wiki.openstreetmap.org/wiki/Map_Features/Units) than the keys have always default units. Which one is the default unit differs from key to key. For example, the default unit for width=* is “meter”, while the default unit for distance=* is “km”. So the default unit is not based on SI units, but on the commonly used unit for this pourpose.
I suppose that in most countries of the world, °C is the common unit for temperature in daily normal live. °F is only used in very few countries. °K is only used in the scientific world, but not in daily normal live. So I think it’s important to have a clearly defined default unit, and this default unit should be °C. Nevertheless, I think it is a good idea to encourage people to tag “with” the unit. Lukas Sommer 2015-02-05 0:53 GMT+00:00 Dave Swarthout <daveswarth...@gmail.com>: > For clarification, the Kelvin temperature scale is almost never used outside > of a chemistry or physics lab. Absolute zero, the lowest possible > temperature, is defined as 0 degrees Kelvin. That is approximately equal to > minus 272 C and minus 460 F. Nobody working on OSM is likely to be > specifying temperatures in degrees K. > > <begin rant> > I also think Americans, and I am one, need to get over the use of degrees F > and the old inch/foot/mile system. It's stupid and anachronistic to base the > units of length on the length of "the king's thumb", or whatever. Continuing > to make exceptions for them is only perpetuating their intransigence. > <end rant> > > This specification is getting quite complex, don't you think? I'm betting we > will never see most of these fine gradations in temperature rendered on a > map. > > my 2 cents > > > On Thu, Feb 5, 2015 at 4:05 AM, Warin <61sundow...@gmail.com> wrote: >> >> On 5/02/2015 1:02 AM, fly wrote: >> >> Am 04.02.2015 um 10:56 schrieb Kotya Karapetyan: >> >> > >> > 1) I would discourage specification of the temperature without the >> > scale indication. I have never lived in the US but I see from the Web >> > that Americans like specifying temperature in degrees Fahrenheit >> > without mentioning it (the same way as we in Europe use centigrade >> > without underlying it). Taking into account the international nature >> > of the OSM community, I foresee a significant risk that the map will >> > get populated with invalid values. Warin is right about SI units, but >> > SI is not even strictly followed in the technical and scientific >> > community, not to mention the general public. Obviously, Americans in >> > general ignore it by using inches, miles and degrees Fahrenheit :) I >> > am afraid many people will not have heard about SI guidelines and will >> > not have read the wiki page in significant detail. >> > >> > Therefore, for the sake of clarity, I suggest always specifying "F" or >> > "C" with the temperature value. >> >> +1 >> Units for temperature are really wired and obviously Kelvin which I >> would suspect to be the default is not really used in real live as >> Celsius has the better scale for real life usage. >> >> >> Matter of common use between C and K. >> The default of height is metres .. not feet. Don't know if there is any >> confusion over that? I do take your point over the default.. insisting on >> the unit may be a good way of ensureing that F is not confused with C. But >> I'd like to see other people ideas on this .. are they prepared to enter the >> unit (even thought it is abbreviated) every time they enter a temperature? >> >> > 2) I suggest clarifying the verbal specification of the temperature. >> > - Replace "chilled" with "cool" (by analogy with "warm") and also >> > because "chilled" actually assumes that I know that the object was >> > purportedly cooled down, which adds yet another uncertainty and is >> > usually not very relevant; >> > - remove the definition of "substantially colder" etc., because it >> > doesn't add any clarity. I agree that it is important to distinguish >> > between safe and unsafe situations, so let's just do that: >> > >> > freezing >> > cold — may be unsafe to handle >> > cool >> > warm >> > hot — may be unsafe to handle >> > boiling >> > adjustable — the object temperature can be changed by consumer/user >> > variable — the object temperature can vary on its own >> > ambient — the object always remains at ambient temperature (note that >> > this may include the object being "cold" and "warm", including being >> > unsafe to handle, depending on the ambient temperature; think about >> > water in Siberia rivers in January) >> >> Only two values I could live with are cold and hot. Generally these >> values are too ambiguous and an estimated value is much better. >> >> >> Chilled as in chilled water is in common use. The mapper may want to >> include it. I don't know how to render that to a map. What a mapper chooses >> to enter is up to them. I'm only rendering adjustable, hot and cold at this >> point anyway. >> >> > 3) For the numeric specification, I suggest adding: >> > - "above"/"below" options >> > - "approximate" value >> > - range of temperatures (using above/below) >> > >> > E.g. >> > temperature:circa = 80 C >> > temperature:above[:circa] = 300 C >> > temperature:below[:circa] = 1000 C >> >> I would add this in the value like: >> >> temperature = < 10 C >> temperature = > 300 C >> >> We still can use source:temperature=estimated >> >> >> No .. you'd have a conflict e.g. >> temperature = 45 >> temperature = estimated >> >> ? which 'value' is 'correct' ' >> >> Might be better as >> >> temperature = 45 >> temperature:accuracy = estimated >> >> >> >> 4) How do we tag a shower with cold and hot water ? >> >> temperature=4 C;80 C ? >> >> Does this depend on the hose, e.g. one separate for each temperature or >> a mix-batterie ? >> >> temperature=adjustable .. that is what it is for ... may be an e.g. after >> the description? >> >> _______________________________________________ >> Tagging mailing list >> Tagging@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/tagging >> > > > > -- > Dave Swarthout > Homer, Alaska > Chiang Mai, Thailand > Travel Blog at http://dswarthout.blogspot.com > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging