With averaging, if the random errors dominate the systematic errors, you will in fact have a better idea where the road is. IIRC, during the course of several hours ionospheric delays would cause systematic errors, but if you instead drive/ride the same road on different days, it's going to be relatively random.
Around Vancouver, I know of at least one place where Geobase is less precise than data I have from my GPS (my 20+ tracks can not be all wrong and offseted _in the same direction_). Needless to day, I moved the GeoBase road to match the averaged tracks in that place. Michael. On Mon, Nov 16, 2009 at 7:26 PM, James Ewen <[email protected]> wrote: > On Mon, Nov 16, 2009 at 6:48 PM, john whelan <[email protected]> > wrote: > > > Multiple approximations can often be very accurate when averaged. > > I agree... put a commercial grade GPS on a spot, and record the > results over a long enough period, you can come up with a close > approximation of where they device was located. > > However, driving up and down a road 5 or 6 times is not going to give > you a superior representation of where the real road is located. You > are not going to get the exact same locations recorded on each > subsequent trip down the road, so each location has to be looked at as > a point of dubious quality. > > The OSM project is always going to be of "dubious quality" because of > the equipment used to capture the data, and the abilities of the > person doing the data entry. > > Those needing super accurate data need to be looking elsewhere. This > project will never be able to provide sub-metre accuracy. > > From my observations, the GPS accuracy that I regularly observe puts > me within 5 to 15 feet or 2 to 5 meters of reality. This would be in > line with the GeoBase stated accuracy factor as well. > > James > VE6SRV > > _______________________________________________ > Talk-ca mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-ca >
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