1. A method of estimating changes in an object represented by first and second multidimensional datasets, where the first dataset is a reference dataset and the second dataset is an altered dataset, the method comprising: processing discrete data samples of the first dataset to form a piecewise continuous representation thereof; computing an error function for comparisons between discrete data samples in the second dataset and the piecewise continuous representation of the first dataset; determining an alteration of the second dataset relative to the first dataset that minimizes the error function; and performing at least one of storing or outputting parameters of the alteration.