On 08.04.2014 11:45, François Lacombe wrote: > Hi, > > Here is a topic discussed with a few people during State Of The Map FR > last week end in Paris. > > Some features mapping would require to tag their azimuth as for knowing > how they are really installed in the environment. > > For instance, benches mapped with nodes may be tagged with azimuth=* > because nodes don't tell which direction the bench follows.
Think the tag is direction=* [1] but there is no explanation how to measure. > But how contributors can measure it ? > > Common devices like smart phones carry compass captors, used by compass > applications. > These captors only sense the magnetic north to determine the azimuth of > the device. The magnetic north is continuously diverting from the > geographic north. > Using the magnetic north isn't a good idea since the azimuth will be > continuously changing instead from the geographic azimuth. > There will be the same question regarding standard compasses. > > Magnetic diversion is mathematically known and such azimuth could be > converted into geographic ones. > > Is there a solution to that issue ? Take a photo to have a reference point either to adjust your compass results later or to completely measure later. Cheers colliar [1] https://wiki.openstreetmap.org/wiki/Key:direction
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