Geoscience Reference
In-Depth Information
MRLC data
1
2
3
4
8
9
Tot
%
Corr
1
87
3
10
0
2
6
108
0.81
87
2
0
188
9
4
38
4
243
0.77
188
3
1
12
134
21
8
9
185
0.72
134
4
1
46
45
227
30
39
388
0.59
227
8
1
43
78
21
207
12
362
0.57
207
9
8
6
24
18
4
127
187
0.68
127
Tot
8
298
300
291
289
197
1473
%
0.89
0.63
0.45
0.78
0.72
0.64
0.66
Corr
87
188
134
227
207
127
970
and mixed forest, deciduous forest and mixed forest, barren ground and other grassland, low-
intensity residential and mixed forest, and transitional and all other classes.
The difference between image classification and photo interpretation is that image classification
is mostly based on the spectral values of the pixels, whereas photo interpretation incorporates color
(tones), pattern recognition, and background context in combination. These issues are inherent in
any accuracy assessment project using aerial photos as the reference data (Ramsey et al., 2001).
For this project, however, aerial photos were the only reasonable reference data source.
The interpretation process is not the only component of the accuracy assessment process
(Congalton and Green, 1999). Additional factors that should be considered are positional and
correspondence error. To account for these errors, the following additional criteria for correct
classification were considered in this project: (1) primary matches classified pixel, (2) primary or
alternate matches classified pixel, (3) primary is most common in classified 3
¥
3 pixel areas, (4)
primary matches any pixel in a classified 3
¥
3 pixel area, (5) primary is most common in classified
3 pixel area. “Interpreted”
refers to the classes chosen during the aerial photo interpretation process, “primary” and “alternate”
are the most probable LC classes for a particular site, and “classified” refers to the MRLC
classification result for that site. The analysis results for each cover class in six cases are presented
in Table 7.5 and Table 7.6. The overall accuracies under various scenarios ranged from 44% to
79.4% (
3
¥
3 pixel area, and (6) primary or alternate matches any pixel in a 3
¥
n
= 1473) for cases “a” and “f,” respectively.
Table 7.5
Summary of Further Accuracy Analysis by Interpreted Cover Class: Number of Sites
Primary PI
Matches
MRLC
Prim or Alt
Matches
MRLC
Primary PI
Is Mode of
3
¥
3
Primary PI
Matches
Any 3
¥
3
Prim or Alt
PI Is Mode
of 3
¥
3
Prim or Alt
PI Matches
Any 3
¥
3
Class
No.
1.1
108
87
95
84
92
94
100
2.1
155
47
69
60
81
124
135
2.2
19
10
11
8
11
15
16
2.3
69
32
39
35
41
44
49
3.1
69
33
35
27
30
34
42
3.2
38
34
36
34
36
35
37
3.3
78
33
44
33
42
40
52
4.1
99
46
55
60
68
79
83
4.2
61
34
39
44
48
52
54
4.3
228
62
98
68
110
148
187
8.1
103
28
39
27
38
46
64
8.2
128
57
82
56
83
83
102
8.5
131
41
61
33
53
56
91
9.1
96
43
53
47
59
68
84
9.2
91
60
68
58
67
67
74
Totals
1473
647
824
674
859
985
1170
