1. A method, comprising: performing, by one or more computing devices, nonlinear self-calibration on a plurality of images in an image sequence to convert a projective reconstruction for the image sequence to a metric reconstruction of camera motion and camera intrinsic parameters for the image sequence, wherein said performing nonlinear self-calibration comprises: determining at least two sets of initial values for an equation to be optimized according to a nonlinear optimization technique; optimizing the equation using each set of initial values according to the nonlinear optimization technique to generate a result for each set of initial values, wherein each result includes estimates of one or more camera intrinsic parameters and of camera motion parameters; selecting the result with a smaller cost according to a cost function; and generating a metric reconstruction for each of the plurality of images according to the selected result, wherein the metric reconstruction includes an estimate of one or more camera intrinsic parameters and of camera motion parameters for each image.