Graphics Reference
In-Depth Information
and
P
uv
=
cos u
i
+
v
j
−
sinu
k
(10.16)
From Eq. (10.16) this makes
P
u
=−
sinu
i
−
cos u
k
P
v
=
j
i
j k
P
u
×
P
v
=
N
=
−
sinu 0
cos u
010
−
N
=
cos u
i
−
sinu
k
P
u
,
P
v
, and
N
.
Figure 10.10 illustrates the orientation of the three vectors
∂
P
∂v
∂
P
∂u
N
Figure 10.10.
Now let's assume that the height field F uv
∈
0 255 and contains the values shown in
Fig. 10.11.
222
215
223
218
v
210
217
214
200
205
210
215
u
Figure 10.11.
