Biology Reference
In-Depth Information
Let us take a simple example. Consider the two objects shown in
Figure 4.8
whose landmark coordinates are provided below.
Let and .
The corresponding form matrices (with numbers rounded to two
significant digits) are given by
0
1
1 41
.
1
1
0
1
1 41
.
FM
()
141
.
1
0 1
1
.
11 0
and
0
1 22
.
2 19
.
1 1
.
122
.
0
175
.
177
.
FM
()
2 19
.
1 75
.
0
1 65
.
11
.
177
.
165
.
0
The form difference matrix, in the vector form, can then be given as
122
155
110
175
125
165
.
.
.
.
.
.
FDM A B
(,)
The value of
T
for the
FDM
of these two objects is the ratio of the
maximum entry (1.75) and the minimum entry (1.10) and hence
T
1.59. Now suppose we delete landmark 3 from both objects and re-cal-
culate the value of
T
for the objects that now consist only of landmarks
1, 2, and 4. The new value of
T
, 1.14, is much closer to 1 than the orig-
inal
T
calculated using all landmarks. After deleting landmark 3, the
value of
T
indicates that the remainders of the two objects are more
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