Automatic Tracking Salient Line Segments of Road Tunnels for Vehicle-Mounted Video Sequences

Tunnel LED lighting system is an important infrastructure to ensure the safety and comfort of driving in highway tunnels. There had been a series of researches about analyzing these LED lamps working state by detection of missing LED lamps in highway tunnels. In this paper, an automatic tracking method for the salient line segments in highway tunnels, the left and right critical boundaries between the top dark area of the tunnel and the white side wall, is proposed for vehicle-mounted video processing. This method includes the following two aspects. Firstly, a three-phase algorithm was proposed to detect the salient line segments by analyzing the geometric structure of the tunnel interior environment, after the line features were extracted by the LSD operator. In this step of processing, the set of parallel line segments converging on the vanishing point in front of the vehicle and the front-vehicle vanishing point itself should be computed as the intermediate results. Secondly, the visual features were extracted in the extended rectangles, which can be formed easily by extending the line segment outward with external equal distance amplification in the initial frame, and tracked in continue frame with more efficiency and more tolerance to larger displacement. The salient line segments extracted in the initial frame can be tracked in the next frame, using the corresponding relationship embedding with the displacement of the same feature points in the two consecutive frames. The experimental results show that the satisfactory results for tracking the salient line segments are obtained, and meet the actual needs of reducing the disturbance of vanishing point estimation in continuous on-board video and improving the recovery performance of geometric information in road tunnels.