Vanishing point estimation by spherical gradient

In this paper we propose a novel method of estimating vanishing point by spherical gradient. In contrast with the conventional methods in which vanishing point is estimated from lines, the proposed method does not necessarily extract lines, but employs the spherical gradient cues of edge points. Based on the observation that spherical gradient is aligned with the normal vector of the projection plane of space lines, the vanishing point is estimated directly from spherical gradient of edge points by the Hough Transform.