Abstract
Automatic inference of depth/distance information is a primary goal of computer vision systems. Although the stereovision method is often used for computer vision, finding matching pairs between frames can often be problematic, particularly when there are several possible matching points. In order to cope with these problems, we have developed a depth measurement system that uses a single CCD camera. By placing the optical device in front of the camera lens, the image of a target recorded on the image plane is displaced by an amount related to the distance between the camera and the target. When the optical device is rotated physically at high speed during the exposure of the camera, the image of a moving target traces a spiral streak. Since the size of the streak is inversely proportional to the depth, and since the pitch and the variation in the size of the spiral is related to the velocity of the moving target, the 3-D information of the target can be obtained by analyzing the streak. In order to make image processing easier, the spiral streaks and their corresponding centerline are recorded on the same image. The centerline is used in computer processing to analyze the streaks. The developed method has been applied to the measurement of moving tracer particles in a flow, and satisfactory results were obtained.
