Gervase Markham wrote: >Sent: 24 January 2008 10:34 AM >To: talk@openstreetmap.org >Subject: Re: [OSM-talk] Mapping canals > >Sven Grüner wrote: >> I don't know of any country using the metric system that is familiar >> with the term "kph". The unit symbol is "km/h" and so everbody uses >*kmh*. > >Google understands kph: >http://www.google.com/search?ie=UTF-8&oe=UTF- >8&sourceid=navclient&gfns=1&q=30mph+in+kph > >So this is just another example of why allowing people to use any unit >"as long as they label it" is a bad idea :-) >
Google and other data users are provided with their data in detailed and specified formats by external contractors. They know at the outset what the units for a given data set are. Thus it's relatively easy for them to provide a response to users with any suitable conversion they wish. You could decide on a strict set of tags for OSM and use these to define certain attributes. Thats fine for making it easier to code and deliver reliable data to users but absolutely useless if this precisely formatted data doesnt exist in the database, and thats the reality we face. Contributors of data to OSM are not professionals working to a strict code of practice, so we can never guarantee that general contributions will be in metric, imperial or wigets. If a group of OSMers wish to set up a strict standard following process then thats fine but of course it's going to be limited to small amounts of data and small geographical areas. The alternative is to accept the limitations of the model and work out ways of using what data exists in a flexible way. If the units are given then its a doddle (even if the form varies), if no units are given then it is most likely the unit implied is the convention for the location (eg miles for UK, USA or km for rest of Europe etc). OSM will always need smart and sophisticated processing. Cheers Andy _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk