1. A method, comprising: performing, by one or more computers: obtaining three point-correspondences P 1 , P 2 and P 3 for a pair of images, where each point-correspondence represents a different feature point that occurs in both of the images; composing a set of three parametric equations with three unknowns from the three point-correspondences P 1 , P 2 and P 3 , wherein the three unknowns include focal lengths f 1 and f 2 each corresponding to a different one of the pair of images and a radial distortion coefficient κ for the pair of images; solving the set of three parametric equations to generate estimates for f 1 , f 2 , and κ; computing an estimate of relative rotation R for the pair of images from the three point-correspondences P 1 , P 2 and P 3 and the estimates for f 1 , f 2 , and κ; and outputting the estimated relative rotation R, focal lengths f 1 and f 2 , and radial distortion coefficient κ for the pair of images.