1. A surgical navigation method comprising the acts of: establishing a coordinate frame by fixing a first electromagnetic device to a patient; acquiring two or more two-dimensional fluoroscopic images of the patient each from a different perspective using an imaging apparatus, the imaging apparatus comprising a source of X-ray radiation and an X-ray detector having a second electromagnetic device and a calibration target affixed thereto, and wherein the calibration target comprises a series of radiopaque markers that are fixed in relation to one another; modeling a geometry of the source of X-ray radiation and the X-ray detector based at least on a geometry of the radiopaque markers in each two-dimensional fluoroscopic image to obtain a perspective from which each image was taken; providing a pre-operative three-dimensional image, the two or more two-dimensional fluoroscopic images, tracking data representing a position and orientation of the second electromagnetic device with respect to the first electromagnetic device, and the perspective from which each two-dimensional fluoroscopic image was taken to a computerized navigation system; generating a respective two-dimensional projection via digital radiographic reconstruction (DRR) of the pre-operative three-dimensional image using the perspective from which each two-dimensional fluoroscopic image was taken and an input pose of the imaging apparatus relative to the pre-operative three-dimensional image; comparing the generated two-dimensional projections to the acquired two or more two-dimensional fluoroscopic images; updating the input pose based on the comparison to generate updated projections via DRR until the updated projections meet a predetermined matching criteria with the acquired two or more two-dimensional fluoroscopic images, the predetermined criteria being a result of a registration pose; and generating a substantially real-time three-dimensional visualization of the patient based on the registration pose and the pre-operative three-dimensional image.