Geography Reference
In-Depth Information
Question: “How can we generate the mapping equations of
such a conformeomorphism?”
Answer: “Let us work out this in the following passage in
more detail.”
The forward computation of the meridian arc length r = f ( Δ ) supplies us with the radial coordi-
nate r of an equidistant mapping of a point of the ellipsoid-of-revolution to a corresponding point
on the tangential plane at the North Pole: compare with Lemma 8.8 . The central problem we
are left with can be formulated as follows: given the radial coordinate r , find the surface normal
ellipsoidal latitude Φ . Such a problem of generating the inverse function can be solved by series
inversion. For details, we here have to direct you to Appendix B , where the standard series
inversion of a homogeneous univariate polynomial is outlined, and where additional references of
how to do it are given. Basic formulae are supplied by Lemma 8.9 .
Fig. 8.4. Conformal mapping of the ellipsoid-of-revolution onto a tangential plane: normal aspect, P
E 2 A 1 ,A 2 ,p
= π ( P ), not UPS
Lemma 8.9 (Meridian arc length, inverse computation).
A forward computation of the meridian arc length based upon a uniform series expansion is
provided by formula ( 8.39 ). Its inverse function can be represented by
Φ = π
r
A 1 E 0 − F 2 sin 2
r
A 1 E 0 − F 4 sin 4
r
A 1 E 0 − F 6 sin 6
r
A 1 E 0
2
(8.41)
r
A 1 E 0 − F 10 sin 10
r
A 1 E 0 +O( E 12 ) ,
−F 8 sin 8
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