1. An image registration process comprising: acquiring a two-dimensional image using a two-dimensional imager comprising an x-ray fluoroscopy apparatus; acquiring a three-dimensional image using a three-dimensional imager comprising a magnetic resonance imager (MRI) or a computed tomography (CT) imager; extracting a two-dimensional set of features from the two-dimensional image; extracting a three-dimensional set of features from the three-dimensional image; mathematically projecting the three-dimensional set of features into a two-dimensional set of projected features using a projection geometry; first registering the two-dimensional set of features and the two-dimensional set of projected features, the first registering including adjusting one or more parameters of the projection geometry selected from a group consisting of an angulation parameter, a magnification parameter, a source location parameter, a detector location parameter, and a distortion parameter; and second registering the two-dimensional image and a mathematical projection of the three-dimensional image using parameters derived from the first registering including using the adjusted parameters of the projection geometry for the mathematical projection of the three-dimensional image.