Geography Reference
In-Depth Information
Table 22.25 Distortion energy of the special harmonic map
L E
dL B N
B S
M
N coscos B
x 01 +4 y 02 l 2 +8 y 02 y 12 bl 2 + O (4) dB + 1
2
1
2
= 1
2
d S l tr C l G 1
l
L W
L E
dL B N
B S
y 01 +4 y 10 y 20 b +
N coscos B
M
L W
(4 y 20 +6 y 10 y 30 ) b 2 +2 y 10 y 12 l 2 + O (3) dB
(22.143)
“Taylor expansions”
E 2
E 2
M
cos B =
1
1
E 2 sin 2 B =
E 2 sin 2 B 0
1
1
1! 1
E 2 sin 2 B 0 2 E 2 sin2 B 0 b + O (2)
+ 1
···
(22.144)
E 2 sin 2 B
1
E 2 sin 2 B 0
1
E 2
cos B
M
= 1
= 1
sin2 B 0 b + O (2)
(22.145)
E 2
E 2
1
E 2
dS l tr C l G 1
l
E = 1
2
B S ) l E + e 21 ( B N
B S ) l E + e 13 ( B N
B S ) l E + O (5)
= e 11 ( B N
(22.146)
l E := L E
L 0 = L 0
L W ,L E
L W =2 l E
(22.147)
1 − E 2
1 − E 2
B 0 + 1 E 2 sin 2 B 0
1
x 01
E 2 sin 2 B 0 x 01
y 10
e 11 :=
+4
E 2 sin 2 B 0
E 2 sin 2 B 0
E 2
1
1
E 2 sin 2 B 0
1
E 2 sin 2 B 0
1
4 1
y 10 y 20 B 0 + 1
y 10 B 0
(22.148)
E 2
E 2
E 2 sin 2 B 0
1
E 2 sin 2 B 0
1
E 2
1
E 2 sin 2 B 0 x 01 +2 1
1
2
y 10
e 21 :=
y 10 y 20
(22.149)
− E 2 sin 2 B 0
E 2
E 2
1
E 2
1
2
9 y 02 y 12 B 0
e 13 :=
(22.150)
E 2 sin 2 B 0
1
22-5 Case Studies
Two case studies illustrate the operational approach to the new harmonic map including the
distortion analysis by means of Tissot ellipses.
The first example is defined by a harmonic map with L 0 =9 as the longitude of the Reference
Meridian of the International Reference Ellipsoid .The Reference Parallel Circle with B 0 = ± 30
as the Gauss ellipsoidal latitude has been chosen. Figure 22.4 illustrates the harmonic map in the
range B ∈ [ 40 , +40 ] andL ∈ [ 31 , +49 ].
In order to compare the new harmonic map of the International Reference Ellipsoid with
Gauss-Krueger conformal maps and UTM we have computed the second example for the Ref-
erence Meridian L 0 ∈{
6 , 9 , 12 , 15 }
and the Reference Parallel Circle B 0 =51 in the range
[46 , 56 ] ,L
[4 . 5 , 7 . 5 ];[7 . 5 , 10 . 5 ] ; [10 . 5 , 13 . 5 ];[13 . 5 , 16 . 5 ]
B
∈{
}
. Indeed we have chosen
a strip width of 3 with l
1 . 5 , +1 . 5 ] around the Reference Meridian L 0 . Obviously the Tissot
distortion ellipses vary slowly within the Meridian Strip. Only at the point ( L 0 ,B 0 )wecanenjoy
isometry as illustrated by Fig. 22.5 .
[
 
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