Geography Reference
In-Depth Information
20-4 Fermi Coordinates: Oblique Geodetic Parallel Coordinates
Fermi coordinates: oblique geodetic parallel coordinates. Geodetic projection. The two-step
solution and the two-step solution equations.
E. Fermi (1901-1954), Italian-American physicist, developed special geodetic coordinates which
might be called “oblique geodetic parallel coordinates”. They are generated as outlined in
Box
20.8
. Compare with Fig.
20.7
.
Fig. 20.7.
Fermi coordinates
{
x, y
}
.
α
FP
=
α
F
0
+3
π/
2
Box 20.8 (Oblique geodetic parallel coordinates, Fermi coordinates).
Choose an
origin P
0
(
L
0
,B
0
) of an arbitrary coordinate system and a second point
P
(
L, B
)
moving on the ellipsoid-of-revolution. Choose a
fixed reference point P
F
(
L
F
=
L
0
,B
F
). The first
coordinate axis is generated as the
geodetic projection
of the point
P
onto the point
P
F
.
The second coordinate axis can be arbitrarily chosen, for instance, as a second geodetic pro-
jection of the point
P
F
onto the point
P
0
, which meets at the point
P
F
at right angles. Such
a pair of coordinates
establishes two geodesics, which are easily computed once
P
0
and
P
F
are fixed. Here, we only present the two-step solution. We note in passing that the one-step
solution operates as described in Sect.
20-3
dealing with Soldner coordinates.
{
x, y
}
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