Circular shifting method enables a three-dimensional measurement of particle movement using a single TV camera and an image-shifting device. By introducing a refractor on the TV camera lens, the image of the tracer particle undergoes a displacement on the image plane that is related to the distance between the TV camera and the tracer particle. When the refractor is rotated at high speed (3,600 r/min) during the TV camera exposure, circular streaks appear on the image due to the rotational shift. Since the size of the circular streak is inversely proportional to the distance of the measuring point from the camera, each streak contains 3D information about a measuring point, and this information can be extracted by processing the streak image. In this paper, combination method between circular shifting and stereovision method is introduced. By this combination, defects of each method are compensated and measurement accuracy is improved.

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