1. A computer-implemented method, comprising: applying an initial unwarping function to coordinates of each feature point in a set of feature points extracted from a set of distorted component images to generate a set of substantially rectilinear feature points for the set of component images; estimating focal lengths and initial camera rotations for each of the component images according to the substantially rectilinear feature points; refining the initial unwarping function according to the estimated focal lengths for the component images to generate refined unwarping functions for the component images; and applying a global nonlinear optimization technique to the refined unwarping functions and the initial camera rotations to generate globally optimized unwarping functions and globally optimized camera rotations for the component images.