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Videogrammetric technique for structural dynamic applications

Authors Ji, Yunfeng
Issue Date 2007
Summary Videogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made with two or more photographic images taken from different positions. This technology is regaining its popularity in various engineering disciplines due to a recent remarkable evolution in the consumer digital cameras. The image resolution of these cameras has increased rapidly from below 1 million pixels a few years ago to over 10 million pixels today, with little increase or even decrease in cost. Image sequences recorded by these cameras contain both spatial and temporal information of the target object; hence can be used to extract the object’s dynamic characteristics such as natural frequencies, damping ratios, and mode shapes. Research indicates that accuracy in the order of as high as 1 part in 30,000 can be achieved when cameras are properly calibrated in the field and multiple high-resolution images are used. In this reserach, several videogrammetric techniques that can be used for measuring responses of flexible structures are presented. These novel techniques include a flexible videogrammetric technique using two-step camera calibration method for 3D measurement in laboratory testing, a non-target mono-vision technique for cable vibration measurement, and a videogrammetric technique for spatiotemporal response measurement in both laboratory and field testing using a general camera calibration method. These techniques are developed based on computer vision theorem such as the optical flow method, the epipolar principle, and camera models. Examples used to illustrate these techniques include response measurement of building models and bridge stay cables. Results show that the videogrammetric techniques have a great potential for accurately measuring displacement responses of structures and investigating structural dynamic characteristics.
Note Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007
Language English
Format Thesis
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