[OSM-talk] satellite precision

[Dirk-Lüder Kreie]

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Iván Sánchez Ortega schrieb:
> El Viernes 26 de Enero de 2007 19:46, Florian Loitsch escribió:
>> I used to adjust my nodes according to yahoo (trusting yahoo instead of my 
>> GPS). Bad idea? 
> 
> Personally, I'd trust your GPS receiver.

that depends, in city centers with highrise buildings or dense
residential areas the gps can be off quite a bit.

> The ideal solution is to rely on geodetic landmarks [1], and check:
> - If they are aligned with the sattelite images
> - If the lat-lon position returned by your GPS receiver matches the theoretic 
> position of the geodetic landmark.
>
> I'm not a topographer, nor a geodesist, nor a mathematician, but If some 
> Really Wise Guys with a bachelor degree/doctorate in all things geographical, 
> says that "that pylon" is located at 2.654328 W, 67.91128 N, I'd rather 
> believe 'em.
> 
> So, if you really have spare time, take the geodetic landmarks as a reference 
> to correct the sat images and your GPS traces.

You must make sure the data is WGS-84 to use it in OSM!
For example the 0-meridian of Greenwich is only for the british system,
the WGS-84 0-meridian is 1500 ft (IIRC) to the east.

Dirk-Lüder "Deelkar" Kreie

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