On Mon, 22 Sep 2008 11:36:30 +0100 "Nick Black" <[EMAIL PROTECTED]> wrote:
> If you had 30 traces down a road and no dop information and you > derived a centre line, using only the lat lons of the 30 different > traces, how much less precise would the result be than taking 30 > traces with dop info and figuring out a centre line? [...] Um, that would depend on the dop info, i.e., does it make some tracks significantly more precise than the others? It is impossible to make a general prediction. In general, given a 1D value x, measured with RMS error, s, from n independent, non-correlated observations; the effect of averaging all n values is that the RMS error of the mean value, <x>, is s/sqrt(n), i.e., the precision to which the 1D position is measured improves as the square root of the number of measurements. Regards, Gora _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
