that allows you to enter at lat/long value and see what the uncertainty
is. The "degree" of uncertainty is related to the number of decimal places
(precision) of the specified lat/long coordinate. Uncertainty is expressed
in kilometers, meters, and miles - not decimal degrees (which are hard to
work with from an application perspective)
The following (new) resource might be of interest:
http://dictionary.uncertml.org/statistics
Many excellent definitions.
Regards
Carl
>> I think that uncertainty should be speicified in meters, independent
>> from the CRS, and the members of the WG that i have spoken to seem to
>> agree.
>
> I agree too.
>
> With uncertainty expressed in degrees one has to understand whether that
> means:
>
> 1. (lat+/-u', lon+/-u')
>
> i.e. the region bounded by (lat-u -> lat+u, lon-u -> lon+u). The
> shape of
> and area of this region depends on where you are on the globe, and you
> also
> get large problems with wrap-around at the poles.
>
> or
>
> 2. (lat, lon) +/- u'
>
> i.e. anywhere within the 3d-chord specified with center (lat, lon)
> subtending
> u degrees. This is a circular region that has almost the same shape
> and area
> everywhere (WGS84 ellipsoid notwithstanding).
>
> It's slightly tricky - personally if someone said " (51'N, 1'W) +/- 1' "
> I'd probably assume definition 1 above, and take that to mean "50 - 52 N,
> 2 - 0 W".
>
> However IMHO definition 2 is more intuitive. It's also much more
> consistent with specifying the uncertainty in meters.
>
> Ray
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