1. A method, comprising: estimating, by a processing device, transformation parameters between a 2-D projection of a volume and a 2-D reference image of the volume in a plurality of search-phases, the estimating comprising: estimating in-plane transformation parameters between the 2-D projection of the volume and a 2-D reference image generated from 3-D scan data of the volume in a first search-phase; and estimating out-of-plane rotation parameters between the 2-D projection and a plurality of 2-D reference images generated from the 3-D scan data of the volume in a second search-phase; and searching, by the processing device, for 2-D transformation parameters in each of the plurality of search-phases using combinations of search techniques and similarity measures in each search-phase.