lume XXXIX-B3, 2012
he image.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B3, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
respectively. With the center pixel as the threshold, its
neighbors (i.e. intersected pixels) are labeled as 1 (where digital
number of the neighborhood is larger than that of the center) or
0 (where digital number of the neighborhood is smaller than
that of the center). Consequently the number of 1 to 0 or 0 to 1
gansition &,-1, £,- and & —s for the circle of radius r=1 , r =3
and r = 5 are computed respectively as follows:
P,
£27 X i£-f9-s£. f (1)
El
P;
(o^ X Beg sJ)-sgars (2)
=
Ps
& 7 X sc g) Schr -17 he)| (3)
kel
Where,
P, is the intersected pixels on the perimeter of the circle of
radius r 71,
P, is the intersected pixels on the perimeter of the circle of
radius r 73,
Ps is the intersected pixels on the perimeter of the circle of
radius r =5.
f,,g., h, is the grey values of the center pixel (pc) and fe -g.- he
and
1 x»'0
s(x)= { (4)
0, x «0
Finally the total transition &r, is calculated as follows:
Eo 725.171,35 (5)
Transition £y, is considered as the LBP value of the center
pixel. The above arrangement is moved over the whole image
until all pixels considered. As a result the original image ‘I’ is
transformed into degree of texture on the basis of its neighbor.
The transformed image is represented here as D? The
presented method for selecting the texture feature value using 1
to 0 or 0 to 1 transitions retains the rotation invariance of the
texture measurement system, since, the number of transitions
do not change if the texture is rotated.
23 Clustering
The Interactive Self-Organizing Data Analysis Technique
(ISODATA) method (Jain et al. 1999; Kohei et al. 2007) is
used to cluster transformed image. It includes three key steps.
First, assign some arbitrary clustering centers in the image.
Next, classify each pixel to the nearest cluster. Last, calculate
all the new cluster centers on the basis of every pixel in one
cluster set. Step 2 and step 3 are iterative and they stop until the
change between two iterations is fine or little. During each
iteration the ISODATA clustering algorithm may have
refinement by splitting or merging clusters. Clusters are
merged if either the number of members (pixel) in a cluster is
less than a certain threshold or if the centers of two clusters are
closer than a certain threshold. Clusters are split into two
different clusters if the cluster standard deviation exceeds a
predefined value and the number of members (pixels) is twice
the threshold for the minimum number of members. ISODATA
clustering algorithm has many benefits such as less computing,
fast computing speed and simplicity as well as un-supervising.
2.4 Results and Discussion
“Lucieer et al’s LBP analysis and ISODATA” and “Proposed
LBP analysis and ISODATA" have been applied on a 3m
spatial resolution RISAT-II X band microwave image (shown
in Figure 2a ) of (i) vegetation, (ii) built-up area, and (iii) water
bodies. Texture is visible in the images. The results of
“Proposed LBP analysis and ISODATA” method is then
compared with the results obtained from the analysis based on
*Lucieer et al's LBP analysis and ISODATA” respectively.
The “Lucieer et al’s LBP analysis and ISODATA” and
“Proposed LBP analysis and ISODATA” methods are applied
on a RISAT-II X-band microwave image are shown in Figure
2b and 2c. In the output images i.e. in Figure 2b and 2c green,
blue and brown colors represents agriculture, water bodies and
built-up area respectively. From the results, it clearly appears
that the “Lucieer et al’s LBP analysis and ISODATA” method
gives heterogeneous segments. While “ Proposed LBP
analysis and ISODATA” method gives more homogeneous
segments with distinct classes than “Lucieer et al’'s LBP
analysis and ISODATA" method.
Using the ground truth data overlaid separately on the resultant
outputs obtained from “Lucieer et al’s LBP analysis and
ISODATA” and “Proposed LBP analysis and ISODATA”
methods, the area statistics of the classification rates for each
approach is shown in Table 1. The numerical results shows that
the success rate for recognizing agriculture, built-up area and
Water bodies are (48.48, 12.23, 58.36) by “Lucieer et al’s
LBP analysis and ISODATA" whereas (82.55, 73.65 and
86.20) by the "Proposed LBP analysis and ISODATA"
approach.