| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 105 === According to the latest statistics of the Soil and Water Conservation Bureau, there are 1705 potential debris flows in Taiwan, all over 159 villages and towns, so it is very important to do a good job in disaster prevention and relief work. The existing earthwork monitoring stations are equipped with fixed outdoor surveillance cameras, but these cameras can only return images for follow-up study of the use of experts, do not have the ability to monitor and warning (such as automatic identification of debris flow and the flow rate, etc.). The purpose of this study is to explore a method for calculating the flow velocity. The research focus is to use the existing zoom cameras to restore the physical three-dimensional information of the image, and then follow the LSPIV technology to realize the monitoring of debris flow. The main method of this paper is to use the optical zoom camera to restore the physical three-dimensional coordinates of the image by changing two focal lengths, and then use the particle tracking velocity technique to calculate the surface velocity of the fluid.
The results of the study include the following points: First, comparing the point-based and area-based depth measurement experiments, it is found that the area-based method is more stable and suitable for practical application. Second, using zoom technology to restore the three-dimensional information of the image, the surface velocity of the fluid in the experimental tank calculated by the method of image processing and the average error is within 10%, Third, a set of parameter calibration experiment is designed for calculating the camera''s internal and external parameters matrix, and the results are reliable.
The significance of this study is that when the debris flow occurs, the elevation of the riverbed changes significantly, then the original reference point coordinates will be destroyed, and the method of changing focus can update the three-dimensional information on the scene real-timely. Through the research, it is proved that applying depth estimation of the zoom images on surface velocity calculation is practical, but the research has not been applied to the monitoring site of the earth flow yet. This is also the future research direction.
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