Optical mapping is a novel technique for generating the restriction map of a DNA molecule by observing many single, partially digested, copies of it, using fluorescence microscopy. The real-life problem is complicated by numerous factors: false positive and false negative cut observations, inaccurate location measurements, unknown orientations and faulty molecules. We present an algorithm for solving the real-life problem. The algorithm combines continuous optimization and combinatorial algorithms, applied to a non-uniform discretization of the data. We present encouraging results on real experimental data.