3D-2D Registration of Curved Objects

Abstract

We introduce here a new scheme for 3D-2D registration of curved objects from images. Having a 3D model of an object, the goal of the registration is to determine the object´s 3D position on the base of 2D images of the object. The optimization methods generally used in this field need a quite precise initial position to avoid the effect of local optima. This paper focuses on the computation of the initial, approximate position, that is typically obtained manually, but it is provided automatically by our new registration method. We represent object models by 2D aspects. As the model aspects and the images are characterized by the same repertoire of local geometric features, a classification of images can be performed by comparing the detected set of features. After identifying the aspect of the object in the images, the parameters of the initial position can be easily determined. The exact position is then the result of an optimization procedure. We are motivated by clinical surgical registration problems involving the registration of human bones. The experiments seem to verify that the presented method provides an adequate initial position information for the optimization procedure in a reasonable intra-operative execution time on a conventional workstation.