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subject to
Λ ( Λ =0)=0 , Φ ( Φ =0)=0 ,
(H.63)
Λ = c 3 Λ,
(H.64)
artanh( E sin Φ )
2 E
sin Φ
+
E 2 sin 2 Φ ) =
(H.65)
2(1
= c 4 artanh( E sin Φ )
.
sin Φ
+
2 E
E 2 sin 2 Φ )
2(1
If E =0 , then
sin Φ = c 4 sin Φ.
(H.66)
If E
=0 , then
sin Φ =
= c 4 sin Φ 1+ 2
15 E 4 sin 4 Φ (9 20 c 4 +11 c 4 )+O( E 6 ) .
3 E 2 sin 2 Φ (1 − c 4 )+ 1
(H.67)
As prepared by Boxes H.2 and H.3 , we can finally present by Lemma H.5 the equiareal mapping of
the biaxial ellipsoid with respect to a transverse frame of reference and a change of scale, in short
the Hammer projection of the biaxial ellipsoid . In particular, the transfer of the four characteristic
terms
,namely( H.34 ), being functions of Λ = c 3 Λ and sin Φ (sin Φ ; c 4 ), has to be
made. While case (i) of Corollary H.6 highlights the general ellipsoidal Hammer projection, case
(ii) is its specific form for zero relative eccentricity, E = 0, namely its spherical counterpart. For
the choice c 1 =2 ,c 2 =1 ,c 3 =1 / 2 ,c 4 = 1 of case (iii), we receive by means of ( H.89 )-( H.92 )the
ellipsoidal mapping equations of special equiareal projection in the Hammer gauge. In contrast,
case (iv) specializes, for E =0.( H.96 ) to the spherical mapping equations in the Hammer gauge,
indeed the original Hammer mapping equations ( Hammer 1892 ). Various alternative variants of
the ellipsoidal mapping equations of equiareal type can be chosen, for different gauge constants
{
t 1 ,t 2 ,t 3 ,t 4 }
{
as long as they fulfill c 1 c 2 c 3 c 4 = 1. In particular, they refer to a pointwise map of
the North Pole or not or to other criteria.
c 1 ,c 2 ,c 3 ,c 4
}
Lemma H.5 (The equiareal mapping of the biaxial ellipsoid with respect to a transverse frame
of reference and a change of scale (the Hammer projection of E
A 1 ,A 2 )).
2
A 1 ,A 2
subject to A 1 = A 1 ,A 2 = A 2 onto the transverse tangent plane normal to E 3 and with respect
to a change of scale is equiareal if
2
A 1 ,A 2
The mapping of the right biaxial ellipsoid
E
with respect to left biaxial ellipsoid
E
x = c 1 r ( Λ, Φ ; c 3 ,c 4 )cos α ( Λ, Φ ; c 3 ,c 4 ) ,
(H.68)
y = c 2 r ( Λ, Φ ; c 3 ,c 4 )sin α ( Λ, Φ ; c 3 ,c 4 ) ,
(H.69)
subject to
 
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