Open AccessPrecise vehicle speed measurement for law enforcement applications based on calibrated camera with parallel standard patterns
Author(s) -
Eslami Hamed,
Raie Abolghasem,
Faez Karim
Publication year - 2016
Publication title -
iet computer vision
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.38
H-Index - 37
eISSN - 1751-9640
pISSN - 1751-9632
DOI - 10.1049/iet-cvi.2014.0325
Subject(s) - computer science , calibration , algorithm , law , computer vision , artificial intelligence , mathematics , statistics , political science
Common VSM (vehicle speed measurement) methods lack either necessary precision and/or flexibility to be used conveniently in law enforcement applications. In this study, a new method is proposed for simultaneous camera calibration and VSM compensating for these problems. The contribution of this study is to give a solution to the degeneracy problem of the Zhang's algorithm while dealing with parallel planar patterns and using the calibration data to estimate vehicle's speed. In applications like estimating the vehicle's speed in straight roads in which the license plates are parallel to each other, the number of linearly independent equations is reduced to 2 and the method cannot be used. In this study, the degeneracy problem of the Zhang's algorithm in dealing with parallel patterns is solved. Using orthonormal properties of all rotation vectors, the number of linearly independent equations is increased from 2 to 5 and camera calibration and VSM are performed simultaneously. Results of implementing this algorithm on real images taken by law enforcement cameras show that the proposed method can estimate the vehicle's speed with a mean of errors less than 1.22 km/h and consequently is proper for law enforcement applications.