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Tham khảo tài liệu 'geoscience and remote sensing, new achievements part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 168 Geoscience and Remote Sensing New Achievements Fig. 5. Wishart supervised classification H A a Land use Forest Agricultural Area 1 Agricultural Area 2 Water Wetland Urban Forest 90 1 3 0 0 5 Agricultural Area 1 2 86 2 0 0 10 Agricultural Area 2 6 0 93 0 0 1 Water 0 0 5 91 0 2 Wetland 1 4 2 1 91 1 Urban 7 23 7 0 0 63 Table 2. Confusion matrix . Rows represent user-defined groups while columns represent segmented clusters 3.1 Multi-polarization analysis The relationship between the mean backscattering with soil drainage classes and synthesized polarizations is given in Figures 6 and 7 for the two designated agricultural areas. An increase of the backscattering signal is observed for these areas and for all polarizations as a function of soil moisture as depicted by theoretical models IEM Fung 1994 SPM and GO Ulaby et al. 1986 and soil drainage classes. For the agricultural Area 1 there are significant differences about 4dB between well-drained D3 D4 and poorly-drained soil classes D5 D6 Figure 6 . Unfortunately there were no data for the very poorly-drained soil class D7 . For the agricultural Area 2 three sets of drainage classes can be distinguished D3 D4 D5 D6 and D7. The VV backscatter is slightly greater than the HH polarization for the two areas. According to Dobson and Ulaby 1986 this result may be due to the high incidence angle 33 to 66 of acquisition for the SAR image. Therefore differences in the mean backscattering signal behaviour for the first three soil drainage classes in the two agricultural areas indicate that scattering mechanisms differ among these fields. Meteorological conditions prevailed until the date of harvest and therefore land cover was highly variable ploughed fields forage cereal soybean or harvested corn 169 Potential of C-Band Multi-polarized and Polarimetric SAR Data for Soil Drainage Classification and Mapping harvested but not ploughed fields with crop residue and unharvested corn fields. In this context polarimetric parameters
