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This paper exploits an effective water extraction method using SAR imagery in preparation for flood mapping in unpredictable flood situations. The proposed method is based on the thresholding method using SAR amplitude, terrain information, and object-based classification techniques for noise removal. Since the water areas in SAR images have the lowest amplitude value, the thresholding method using SAR amplitude could effectively extract water bodies. However, the reflective properties of water areas in SAR imagery cannot distinguish the occluded areas caused by steep relief and they can be eliminated with terrain information. In spite of the thresholding method using SAR amplitude and terrain information, noises which interfered with users’ interpretation of water maps still remained and the object-based classification using an object size criterion was applied for the noise removal and the criterion was determined by a histogram-based technique. When only using SAR amplitude information, the overall accuracy was 83.67%. However, using SAR amplitude, terrain information and the noise removal technique, the overall classification accuracy over the study area turned out to be 96.42%. In particular, user accuracy was improved by 46.00%.

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This study proposes a crack-monitoring system to quantify the change of cracks from multitemporal images during the monitoring period. A series of images were taken from an off-the-shelf digital camera. Concrete cracks were extracted from the digital images by employing a series of image-processing techniques. The image coordinates and orientation of same cracks can be changed since the position and direction of the portable camera vary at every exposure time. To monitor the crack changes (width and length), it is critical to transform the image coordinates of cracks extracted from each image into the same object coordinates of the concrete surface. In this study, such a geometric relationship was automatically recovered using the two-dimensional (2D) projective transformation based on the modified iterated Hough transform (MIHT) algorithm, the result of which solved the transformation parameters. To improve the computational operation of MIHT, regions of parameter estimation were also investigated. The developed algorithms were applied to monitor the crack of the concrete specimen. As a result, the change of cracks on the concrete specimen was successfully detected and accurately quantified.

consolidation, and absence of intraluminal air. In two patients, the abnormality was not visible on CT. Our experience shows that CT is useful for identifying bronchial stenosis caused by tuberculosis. However, the findings vary, and in more than half of the patients concentric narrowing and uniform thickening of the bronchi are not seen.

A new monitoring system using GPS is introduced to measure wind‐induced responses of high‐rise buildings. In this paper, wind‐induced responses of a long‐period structure include relative lateral displacements, acceleration records, and torsional displacements at the top of a building. After comparing responses of a test model measured by GPS with responses obtained by the most commonly used laser displacement meters and accelerometers, the wind‐induced responses of a 66‐story high‐rise building subject to the yellow dust storm were measured by the GPS‐based monitoring system. Based on the field measurement, it is concluded that the complete motion history of a high‐rise building can be monitored by GPS. Copyright © 2007 John Wiley & Sons, Ltd.