Self-orientation of a hand-held catadioptric system in man-made environments

In central catadioptric systems the 3D lines are projected into conics, actually degenerate conics. In this paper we present a new approach to extract the projected lines corresponding to straight lines in the scene and to compute vanishing points from them. Using the internal calibration and two image points we are able to compute the catadioptric image lines analytically. We exploit the presence of parallel lines in man-made environments to compute the dominant vanishing points in the omnidirectional image. In order to obtain the intersection of two of these conics to compute vanishing points we analyze the self-polar triangle common to this pair. With the information contained in the vanishing points we are able to obtain the self-orientation of a hand-held catadioptric system. This system can be used in a vertical stabilization system required by autonomous navigation or to rectify images required in applications where the vertical orientation of the catadioptric system is assumed. We test our approach performing vertical and full rectifications in real sequences of images.