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A Novel Approach to Rail Crossing Protection Using Computer Vision and Radio Communications

Rodríguez T.

Machine Graphics and Vision

2011

Vol. 20, No. 1

41-71

In the paper we present an innovative computer vision based rail crossing protection system. A camera installed on top of a mast overlooking the crossing continuously monitors the scene, searching for objects that have stopped on the rail tracks. The system is designed to transmit images of the incident to the approaching trains as soon as any conflictive object has been detected. A simple user interface on board of the train displays the image sequence with a graphical aid clearly identifying the offending object in the image. In that way, train drivers are alerted of the presence of possible obstacles well before the train has approached the crossing. The system we describe operates autonomously for long periods of time without human intervention and adapts automatically to the changing environmental conditions. Several innovations, designed to deal with the above circumstances, are proposed in the paper, including: an adaptive segmentation algorithm, an innovative method for the detection of stopped objects and differentiated approaches for day and night processing.

Practical camera calibration and image rectification in monocular road traffic applications

Rodríguez T.

Machine Graphics and Vision

2006

Vol. 15, No. 1

51-71

In this paper we follow apractical approach to the problem of camera calibration and image formation in a typical computer vision based traffic monitoring system. Our study starts by analysing in detail the capturing scenario and the undesirable effects resulting from the application of the pin-hole camera model to traffic images. Based on the acquired experience, we present an integral method to obtain the transformation matrices required to calibrate the camera and to construct in real time a rectified and sub-sampled image where perspective effects on the road plane have been removed. The motivation for this perspective-free image is to reduce the amount of data which must be computed (while avoiding loss of relevant information), remove influences from objects external to the capturing area and simplify the operation of the subsequent detection and tracking stages. The latter statement is justified since vehicle shapes can now be approximated by rectangles, the distance between any two neighbouring points on the road plane remains constant all over the image, and parallel trajectories are restored in the rectified image.