Navigation question (Projecting a waypoint w/GPS)
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On Wed, 19 Jun 2013 15:00:45 -0400, " Sir Gregory Hall, Esq·"
åke wrote:
Charts aren't a fair representation of
the surface of the Earth.
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That's true but it does not relate to this particular issue.
It is too true. The lines of latitude show as parallel on
a Mercator projection chart while on a sphere (like the Earth)
these lines are NOT parallel as the surface of the Earth
is not flat but spherical.
Ask yourself this question: The longitudinal lines everybody
agrees are not parallel as they all run together at the poles and
have maximum separation at the equator, but the *parallels* of
latitude though parallel on the chart are NOT parallel on the
sphere of the Earth. Thus the divergence noted on the Garmin
plotter. A great circle route is actually a straight line across the
Earth's surface but on a Mercator projection it shows as a
curve. What makes you think the opposite isn't true?
HTH.
--
Sir Gregory
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