Estimate the attitude of the camera from the railway-environment images

In this paper, we present a method of estimating the attitude of the camera, i.e. the angle between the optical axis and the direction of the camera's motion, from the image. For the machine vision based railway-environment-surveillance methods, the alignment between the world coordinate system and the camera coordinate system is very important. The alignment error will influence the analyzed results severely, because the scene depth is very large. Thus, estimating the attitude of the camera and adjusting the machine vision algorithms by the attitude-estimation results are important preprocessing steps. Moreover, we give both theoretical analysis and algorithm implementation of detecting the vanishing points based on the selected line segment detector (SLSD) and least-square technique. The experimental results show the validation of our method.