Graphics Programs Reference
In-Depth Information
Eq. (8.56) can be expressed in terms of the directional cosines
u
θφ
=
v
θφ
sin
cos
(8.57a)
=
sin
sin
u
--
φ
=
atan
(8.57b)
u
2
v
2
θ
=
asin
+
The visible region is then defined by
u
2
v
2
+
≤
1
(8.58)
It is very common to express a planar arrayÓs ability to steer the beam in
space in terms of the
UV
,
space instead of the angles
θ φ
,
. Fig. 8.21 shows
how a beam steered in a certain
θφ
,
direction is translated into
UV
,
space.
V
1
U
θ
φ
Figure 8.21. Translation from spherical coordinates into U,V space.
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