Method and apparatus for estimating relative three-dimensional (3D) camera rotations, focal lengths, and radial (lens) distortions from point-correspondences in pairwise (two image) image alignment. A core estimator takes a minimal (three) number of point-correspondences and returns a rotation, lens (radial) distortion and two focal lengths. The core estimator solves relative 3D camera rotations, and lens distortions from 3-point-correspondences in two images in the presence of noise in point-correspondences. A robust estimator may be based on or may be “wrapped around” the core estimator to handle noise and errors in point-correspondences. The robust estimator may determine an alignment model for a pair of images from the rotation, distortion, and focal lengths.