[time-nuts] Averaging Location for Position Hold

[bg at lysator.liu.se]

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>
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> Also, can you really trust Google Earth as an authoritative source?
> I'm not sure.    An interesting test would be to go find a USGS
> benchmark or a section marker near you then enter it's location into
> Google.  See if Google hits the marker.
> --
>
>
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> For what it's worth, my Thunderbolts here did a 48 hour survey, and the
> position they report, fed into google earth, hits the north side of the 3'
> x 3' skylight they are in.
> Roughly 18" error.
>
> Maybe luck, but they both report almost identical positions.  I'm north of
> Denver, so I'm a bit off the spherical average.

Google is very good on many occations and not so good once in a while.
Also note google does not do true orthoimages, so true distance/position
is hard to get where you have altitude differences.

    http://en.wikipedia.org/wiki/File:OrthoPerspective.svg

--
   Björn