Patient Motion Compensation for Photogrammetric Registration

Photogrammetry has evolved as a non-invasive alternative for various medical applications, including co-registration of the patient at the time of a surgical operation with pre-surgically acquired data as well as surgical instruments. In this case body surface position regularly has to be determined in a global co-ordinate system with high accuracy. In this paper, we treat this task for multi-view monocular imagery acquiring both body surface as well as e.g. reference markers. To fulfill the high accuracy requirements the patient is not supposed to move while images are taken. An approach towards relaxing this demanding situation is to measure small movements of the patient, e.g. with help of an electromagnetic device, and to compensate for the measured motion prior to body surface triangulation. We present two approaches for motion compensation: disparity shift compensation, and moving cameras compensation - both capable of achieving patient registration qualitatively equivalent to motion-free registration.