Approximation to the Fisher–Rao metric for the focus of expansion

The Fisher–Rao metric for the focus of expansion is approximated, under the assumption that the focus is estimated from correspondences between two images taken by a translating camera. The approximation is accurate if the errors in the image correspondences are small. The parameter space for the focus of expansion is sampled at a finite set of points chosen such that every point in the space is near to at least one sample point. A focus of expansion is detected by checking each sample point in turn to see if it is supported by the image correspondences.