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APPLICATION OF RAJSKI DISTANCE TO LAND-COVER CLASSIFICATION
USING POLARIMETRIC SAR AMPLITUDE IMAGE DATA
T. Yamada", T. Hoshi?
? Dept. of Electrical Engineering,, Fukushima National College of Technology, 30 Kamiarakawa Taira Iwaki,
Fukushima, 970-8034 Japan - yamada@fukushima-nct.ac.jp
? Dept. of Computer and Information Science, Ibaraki University, 4-12-1 Nakanarusawa Hitachi, Ibaraki, 316-8511
Japan - hoshi@cis.ibaraki.ac.jp
Poster Session, Working Group VII/1
KEY WORDS: Remote Sensing, Land Cover, Classification, Polarization, Algorithms, SAR
ABSTRACT:
Polarimetric SAR can observe scattering matrix for each resolution cell and provide amplitude images that have gray level in
proportion to amplitude of the conjunction matrix elements. However, these amplitude image data have been used for pseudo color
synthesize and construction of feature vector for land-cover classification as the vector elements mainly, discussion about features
derived from amplitude image data was scarcely. In this paper, we consider pattern difference in different polarization amplitude
image of polarimetric SAR as probability, and discuss about contribution of expanding dimension of feature vector by introducing
Rajski distance as a features. To calculate Rajski distance, gray level co-occurrence matrix (GLCM) method that has been often used
for texture analysis was used. In the proposed method, gray levels of the pixel that was located at the same coordinates in two
different transmit and receive polarization amplitude images are adapted to line and column of GLCM, then co-occurrence
probability are calculated. From this matrix, joint entropy and conditional entropy are derived and Rajski distance is found. To
inspect the proposed theory, we investigate the effect of expanding dimension of feature vector for land-cover classification by
Euclid minimum distance method and maximum likelihood method as well known supervised classification method generally using
SIR-C polarimetric data obtained in two kinds of scenes including different land-cover objects. As the results, improvement of
accuracy in the point of classification score and ambiguity scale, so that the effectiveness of introduction of Rajski distance to
expanding dimension of feature vector for land-cover classification is demonstrated.
1. INTRODUCTION Rajski distance is used as a distance measure that indicates the
similarity of two probability phenomenon systems using
The various land-cover classification algorithms using the data entropy. In this paper, Rajski distance is calculated for each
of the polarimetric SAR have been proposed until now, and the pixel by making into a probability phenomenon system the
validity is reported. For example, they are supervised pixel value distribution of the amplitude image data from that
classification methods based on Bayes theory and using neural the combination of two different polarizations of polarimetric
network, and unsupervised classification methods based on SAR data: SIR-C (Shuttle Imaging Radar-C) and airborne Pi-
scattering types and scattering entropy. Each of these SAR (Polarimetric and Interferometric SAR), the distances for
corresponds to full-polarimetric data that used both amplitude some area are characterized, and the application effect of Rajski
information and phase information for each element of distance to land-cover classification is reported.
scattering matrix obtained by polarimetric SAR (Yueh, H. A. et
al., 1988; Ito, Y. and Omatsu, S., 1997; Zyl, J. J., 1989; Cloude,
S. R. and Pottier, E., 1997). However, in the case where whole
information of scattering matrix is acquired, and the situation
that only amplitude information is acquired, some of these
2. CALCULATION OF RAJSKI DISTANCE FROM
POLARIMETRIC SAR IMAGE DATA
techniques cannot be apply or deteriorate classification 2.1 Overview of Rajski Distance
accuracy. In order to analyze to image data only for amplitude
information, the classification technique as a general digital In this section, overview of Rajski distance is described
image are applied. It could judge visually that the difference has (Isomichi, Y., 1980). Two probability phenomenon systems are
arisen in the amplitude image data for the different polarization set to X and Y, respectively, and each phenomenon is set to a; (i
used for observation by polarimetric SAR, when performing — 70. ..., m-1) and b; (j=0, ..., n—1), respectively. The probable
such a classification. Therefore, it is necessary to extract relevance of both phenomenon systems is determined by the
quantitatively the difference in the feature by the difference simultaneous occurrence probability p(a; bj) Joint entropy
kind of polarization that is latent in the amplitude image data of | H(XY) for X and Y is given using simultaneous occurrence
the polarimetric SAR, and to raise classification accuracy with probability as follows.
eg icatı ro . 1 ane si tu m-ln-l
the application of it for dimension extension of the feature H(XY) = ES pia, Pie pie D.) (1)
vector of land-cover classification for amplitude image. In this oe :
paper, application of the Rajski distance based on information The conditional information content A(X) and HHX) are
theory is proposed as the parameter. Although entropy is
ray fa given as follows
conventionally used for the texture analysis of a digital image,
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