title: Gap Measurement of Point Machine Using Adaptive Wavelet Threshold and Mathematical Morphology.
abstract: A point machine's gap is an important indication of its healthy status. An edge detection algorithm is proposed to measure and calculate a point machine's gap from the gap image captured by CCD plane arrays. This algorithm integrates adaptive wavelet-based image denoising, locally adaptive image binarization, and mathematical morphology technologies. The adaptive wavelet-based image denoising obtains not only an optimal denoising threshold, but also unblurred edges. Locally adaptive image binarization has the advantage of overcoming the local intensity variation in gap images. Mathematical morphology may suppress speckle spots caused by reflective metal surfaces in point machines. The subjective and objective evaluations of the proposed method are presented by using point machine gap images from a railway corporation in China. The performance between the proposed method and conventional edge detection methods has also been compared, and the result shows that the former outperforms the latter.
authors.affiliation: State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China. thxu@bjtu.edu.cn.
authors.forename: Tianhua
authors.initials: T
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China. guangwang@bjtu.edu.cn.
authors.forename: Guang
authors.initials: G
authors.lastname: Wang
authors.affiliation: National Engineering Research Center of Rail Transportation Operation and Control System, Beijing Jiaotong University, Beijing 100044, China. hfwang@bjtu.edu.cn.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Computer Science, University of York, York YO10 5GH, UK. tommy.yuan@york.ac.uk.
authors.forename: Tangming
authors.initials: T
authors.lastname: Yuan
authors.affiliation: School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China. 12111056@bjtu.edu.cn.
authors.forename: Zhiwang
authors.initials: Z
authors.lastname: Zhong
keywords: edge detection; image binarization; mathematical morphology; wavelet-based image denoising