A zero-bank algorithm for inverse perspective of a road from a single image

A method is presented for reconstructing the 3-D geometry of a road from a single image of the road. This problem has an infinity of solutions unless restrictive hypotheses about geometric characteristics of this road are assumed. The road is modeled as a space ribbon defined by a spine (centerline) and generators (cross-segments) which are horizontal line segments cutting the spine at their midpoint at a normal angle. Properties of two neighboring generators of such a ribbon are examined; if a generator is known, a neighboring generator is completely defined if one of its ends is known. The proposed method uses this property to reconstruct the visible part of the world road, by iteratively finding a series of generators. This method is tested against a simple method which assumes that the ground is flat ("Flat Earth assumption"), and against another method which uses vanishing points.