1. A method for tree structure based two-dimensional to three-dimensional registration comprising: receiving three-dimensional (3D) data indicative of vessels; segmenting the 3D data with a vessel tree; simulating two-dimensional (2D) data responsive to the segmented 3D data to form a simulated 2D image; receiving 2D data indicative of vessels; segmenting the received 2D data with a vessel tree; finding a distance transform of the segmented 2D data to form a 2D distance map image; using a similarity metric based on the distance map to compare the simulated 2D projection image or points with the segmented 2D image; randomly varying, testing validation or computing the probability based on the similarity metric, and re-sampling poses of the received 2D data relative to the received 3D data based on a particle filtering scheme to keep the most probable poses generating the highest similarity between the simulated 2D image and segmented 2D image; and finding the pose with the highest similarity for registering the received 2D data to the corresponding projection of the received 3D data.