METHODS AND SYSTEMS FOR MAPPING A VIRTUAL MODEL OF AN OBJECT TO THE OBJECT

摘要

A method of and apparatus for mapping a virtual model (100) formed from a scanned image of a part (10) of a patient to that part 10 of the patient. A camera (72) with a probe (74) fixed thereto is moved relative to the part (10) of the patient until a video image of that part (10) captured by the camera (72) appears to coincide on a video screen (80) with the virtual model which is shown fixed on that screen (80). The position of the camera (72) in a real coordinate system (11) is sensed. The position in a virtual coordinate system (110) of the virtual model (100) relative to a virtual camera by which the view of the virtual model (100) on the screen (80) is notionally captured is predetermined and known. From this, the position of the virtual model (100) relative to the part (10) of the patient can be mapped and a transform generated to position the part (10) of the patient in the virtual coordinate system (110) to approximately coincide with the virtual model (100). After completion of such an initial registration process a second, refined registration process can be initiated by acquiring a large number of real points on the surface of the part of the patient under analysis. Such points can then be processed using an iterative closest point measure to generate a second, more accurate transform can be generated. This refined registration process can be iterated and more and more accurate transforms generated until a termination condition is met. Using the final transform generated by this process the virtual model (100) can be positioned in the real coordinate system (11) to substantially exactly coincide with the part (10) of the patient.