538
Table 7. Percent correct classification of nine major cover types by each classification approach.
Classi
COVER
Ì Y P E S
Overall
Perfor-
mance
fication
Approach Com
Forest Grass Industry Roads
Soils Soybean Urban
Water
I
100
a *
100
a
79
a
90
a
84
a
93
a
100
a
97
a
100
a
93.7
0.
0
II
95
a
89
ab
65
ab
83
ab
76
ab
88
ab
99
a
89
ab
100
a
87.1
%
III
99
a
98
a
75
a
87
a
81
ab
80
ab
99
a
98
a
100
a
90.8
0.
0
IV
92
a
73
c
63
ab
83
ab
71
ab
73
b
98
a
92
ab
100
a
82.8
0.
0
V
53
be
78
be
22
d
85
a
62
b
80
ab
86
b
64
cd
100
a
70.0
0,
0
VI
49
be
88
abc
50
be
75
ab
74
ab
74
b
86
b
60
d
100
a
72.9
0.
0
VII
64
b
55
d
40
cd
66
b
82
a
73
b
86
b
58
d
100
a
67.4
%
Vili
44
c
77
be
67
ab
36
c
38
c
49
c
85
b
78
be
100
a
63.8
a
0
MSE (%)
14
13
21
15
14
17
6
14
—
* Within each cover type, approaches followed by the same letter are not significantly different at =0.05
level by the Bonferroni T - test. (Degrees of freedom = 792, Critical value of T = 3.13)
4.12 Computer time evaluation
Considering classifiaction approach I as the standard
procedure, the CPU time consumed for the Maximum Li
kelihood Classifier in this approach (7,783 secs)
was considered as the reference time to compare with
the other approaches.
A reduction in CPU time is result of less channels
used in the classifications.
Table 8. Computer time (CPU) consumption for each
approach.
Classification
Approach
CPU Time Ratio
I
1 : 1
II
1 : 1.3
III
1 : 1.3
IV
1 : 1.3
V
1 : 2.5
VI
1 : 2.6
VII
1 : 4.0
Vili
1 : 4.5
5 CONCLUSIONS
The four data sets examined in this research provide
a method for evaluatting the effect of the TM thermal
infrared band in multispectral classifications. A
Per Point GAussian Maximum Likelihood classification
was performed with eight different approaches. The
analysis of the data sets with all seven bands or the
six reflective bands (i.e., data sets A and B), pro
vided 37 spectrally separable classes. THe use of
four or three Principal Components provide fewer
spectrally separable classes.
The use of the seven TM bands for the analysis pro
cedure gave better discrimination among classes and
fewer mixed classes. This same situation prevails
between data sets C and D where the use of three
Principal Components gave more mixed classes than
set C
The use of the seven TM bands gave the best minimum
and average separability values. If the thermal
band is not included for multispectral classification,
then it is better to generate the training statistics
(cluster) without the thermal band.
Water features show to be equally discriminated with
all the approaches. Soybean and com were better
discriminated with classifications of the data set A.
Urban classifications using statistics generated with
the seven TM bands (data set A) were significantly
different from those of the other three data sets.
Soils and industrial classes in the approach VIII
(Three Principal Components) were significantly di
fferent and had the lowest accuracy mean values.
Classifications performed with data sets B, C and D
provided fores/com mixed classes because of lower
separability values between those features.
In general, classifiactions using the thermal band
were significantly different from classifications
without this band. THe separability values between
pairs of classes were higher when the thermal band was
used.
When there is a constraint on computer tine and/or
hardware, the use of data compression techniques such
as PRincipal Components may be advantageous due to
the drastic decrease in CPU time consumed.
The thermal band itself has great possibilities for
specific types of research, specially in the areas of
thermal pollution mapping, detection of vegetation on
stress situations and mapping of sea currents.
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Anderson, J.R.,E.E. Hady, J.T. Roach S R.E. Witnjer
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Anuta, P.E., L.A. Bartolucci, M.E. Dean, D.F. Lozano,
E. Malaret, C.D. McGillem, J.A. Valdes S C.R. Va
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