On Jan 22, 2008 10:35 PM, Gervase Markham <[EMAIL PROTECTED]> wrote: > Dave Stubbs wrote: > > But some of them will be incorrect. And how do I now make a renderer > > that gives the speed limit in the unit it's actually specified? > > We seem to have a choice between: > > 1) Making renderers which need to understand the units they want to > render on the map, and are capable of converting values in a single > standard unit into that rendered unit and rounding appropriately: > 48.28 -> 29.999mph -> "30mph" > > 2) Making renderers which need to understand all possible units anyone > might use, and how to convert them into the units they want to render on > the map (which may or may not be the units encoded). > 50kph -> 31.07mph -> "30mph" > 45mph -> 45mph -> "45mph" > 73000furlongsperfortnight -> 27.16kph -> "28kph" >
I don't think *renderers* really need to know much about speed limits. If a road is tagged with 73000furlongsperfortnight then a renderer might show that on a map, but it's probably not going to try to convert it to any other units - why would it need to? Route planners, on the other hand, would need to be able to do some conversion in order to calculate journey times and find the quickest routes. But there again average speeds might be more useful than speed limits in this case. Etienne > > I opt for 1). I think it's reasonable to ask renderers to know about > units they want to render. I don't think it's reasonable to ask them all > to know about all possible units anyone might want to stick in the > database. > > Gerv > > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk >
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