For two given point sets, we present a very simple (almost trivial) algorithm to translate one set so that the Hausdor distance between the two sets is not larger than a constant factor times the minimum Hausdor distance which can be achieved in this way. The algorithm just matches the so-called Steiner points of the two sets. The focus of our paper is the general study of reference points (like the Steiner point) and their properties with respect to shape matching. For more general transformations than just translations, our method eliminates several degrees of freedom from the problem and thus yields good matchings with improved time bounds.