教師著作

Permanent URI for this collectionhttp://rportal.lib.ntnu.edu.tw/handle/20.500.12235/31268

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Author: search.filters.author.W.-Y. WangSubject: search.filters.subject.CCD camera

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    Distance Measurement Using Single Non-metric CCD Camera
    (2007-08-26) T.-H. Wang; M.-C. Lu; W.-Y. Wang; C.-Y. Tsai
    A novel measuring system based on a single non-metric CCD camera and a laser projector is proposed in this paper for measuring distance of a remote object. The setup of the measuring system is relatively easy, in which the laser pointer is positioned beside the CCD camera so that laser beam projected is parallel to the optical axis of the camera in a fixed distance. Based on a fast and effective algorithm proposed in this paper, the central position of the projected laser spot in images due to the laser beam can be accurately identified for calculating the distance of a targeted object according to an established formula. Because of the relationship of pixels counts of the diameter of the laser spot at different distances, processing of a sub-frame comprising a fraction of scan lines, rather than the whole image, is only required. Significant savings of computation time can therefore be achieved. Simulation results show satisfactory measurements can be obtained, where averaged absolute measurement errors via the proposed approach lie within 0.502%.
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    A Practical Nighttime Vehicle Distance Alarm System
    (2008-10-15) M.-C. Lu; C.-P. Tsai; W.-Y. Wang; M.-C. Chen; C.-C. Hsu; Y. Y. Lu
    This paper presents a practical nighttime vehicle distance measuring method based on a single CCD image. The method combines an image-based distance measuring system. To solve the nighttime feature extraction problem, the proposed method uses two taillights as the feature. Based on the proportionality of similar triangles, distance between a CCD camera and the taillights of the vehicle ahead can be measured. The method focuses on detecting the taillights and differentiating the targeted vehicle from others on the basis of partial image analysis instead of whole image processing. The system is both fast and simple. The accuracy of the proposed method is demonstrated in this paper through experiences.