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Landslides in Malaysia, and other tropical countries where heavy monsoon rains are common, form a risk to people, buildings, and roads. In particular, steep slopes that have been cut to accommodate road lines are prone to landslides. The objective of the study was to develop algorithms and methods that can be used to alert on increased risk of landslides through detecting small signs of slope instability with synthetic aperture radar (SAR) image analysis. A time series of 19 scenes from the TerraSAR-X satellite was analyzed in study site Gunung Pass. Amplitude image analysis and interferometric techniques were applied to study soil movements. Two terrace fragments were measured to have slid 2.5 and 4.9 m in two amplitude images. The phase of topography-flattened coherence images was used to map small movements in a slope-failure area. The highest movement that was detected with interferometric techniques was 1.71 cm while the corresponding movement in ground data was 2.65 cm. High soil movements (over 16 cm) in the slope failure area prevented the use of phase data because fringes disappeared. [ABSTRACT FROM PUBLISHER]

This paper compares ALOS PALSAR fully polarimetric and dual-polarized data in the application area of land cover mapping. To assure versatile comparison of the data, different classification methods and different features of data are used. Two of the classification methods used are based on supervised classification and two on unsupervised classification. Polarimetric data are used in three ways: 1) as fully polarimetric data; 2) features calculated from fully polarimetric data; and 3) intensity data of selected channels. Combinations of six (water, field, sparse forest, dense forest, peat land, and urban areas), five, four, and three classes were used for classification. Fully polarimetric data gave better results (87.5%–84.7% with three classes; open land areas, forest, and water) than intensity data only (83.6%–78.6%), but the differences in the overall accuracies between the methods were not more than 7.6%. Kappa coefficients of agreement are moderate for all the classifications. Supervised classification can be expected to perform better than unsupervised classification, given that the training areas can be selected accurately. Dual polarization data were found to be an attractive alternative in cases where fully polarimetric data are not available or it is of low resolution. With intensities of selected polarimetric features, it was possible to obtain a high classification accuracy as with fully polarimetric data. This also opens possibilities for nonspecialist users to benefit from polarimetric information in classification. [ABSTRACT FROM AUTHOR]

Describes the synthesize amplitude- and phase-type computer-generated holograms for millimeter-wave fields. Physical operation of holographic grating; Calculation of the required transmittance on the plane of hologram; Lack of direct amplitude modulation.