Geoscience Reference
In-Depth Information
Table 13.1
Number of Samples by Andersen Level I Classes
Class Name
MRLC Code
No. of Samples
Water
11
79
Developed
20s
222
Barren
30s
127
Forested Upland
40s
338
Shrubland
51
0
Nonnatural Woody
61
0
Herbaceous Upland Natural/Seminatural Vegetation
71
0
Herbaceous Planted/Cultivated
80s
237
Wetlands
90s
101
Total
1104
Major analytical study elements were: (1) to define a multilevel agreement between sampled
and mapped pixels, (2) to construct accuracy maps for six LC types, (3) to define cover-type-
conversion degrees of membership for mapped pixels, (4) to develop a cover-type-conversion rule
set for different conditions of accuracy and LC dominance, (5) to construct fuzzy LC maps, and
(6) to develop landscape indicators from fuzzy LC maps.
13.2.1
Multilevel Agreement
In the MRLC accuracy assessment performed by Yang et al. (2001), agreement was defined as
a match between the primary or alternate reference cover-type label of the sampled pixel and a
majority rule LC label in a 3
3 window surrounding the sample pixel. Here we defined a multilevel
agreement at a sampled pixel (Table 13.2) and applied it for all available sampled pixels. It has
been demonstrated that the multilevel agreement went beyond the conventional binary agreement
and covered a wide range of possible results, ranging from “conservative bias” (Verbyla and
Hammond, 1995) to “optimistic bias” (Hammond and Verbyla, 1996). We define a discrete fuzzy
set
¥
)}) representing the multilevel agreement at a mapped pixel regarding
a specific cover type as follows:
A
(
A
= {(
a
,
m
),…,(
a
,
m
1
1
6
6
n
n
d
I
d
ÂÂ
kk
k
d
p
d
p
M
Max
k
k
k
=
1
k
=
1
i
(13.1)
m
=
=
i
n
n
Ê
Á
ˆ
˜
()
M
d
I
d
ÂÂ
i
i
Max
kk
k
i
p
p
d
d
k
k
k
=
1
k
=
1
where
a
,
i
= 1,…,6 are six different levels (or categories) of agreement at a mapped pixel;
m
is
i
i
fuzzy membership of the agreement level
i
of the pixel under study;
d
is the distance from sampled
point
k
to the pixel (
k
ranges from 1 to
n
, where
n
is the number of nearest sampled points taken
Table 13.2
Multilevel Agreement Definitions
Levels
Description
I
A match between the LC label of the sampled pixel and the center pixel's LC type as well as a LC
mode of the three-by-three window (662 sampled points)
II
A match between the LC label of the sampled pixel and a LC mode of the three-by-three window (39
sampled points)
III
A match between the LC label of the sampled pixel and the LC type of any pixel in the three-by-three
window (199 sampled points)
IV
A match between the LC label of the sampled pixel and the LC type of any pixel in the five-by-five
window (84 sampled points)
V
A match between the reference LC label of the sampled pixel and the LC type of any pixel in the
seven-by-seven window (31 sampled points)
VI
Failed all of the above (89 sampled points)
