Oblique-viewing endoscopes (oblique scopes) are widely used in minimally invasive surgery. The viewing direction of an oblique endoscope can be changed by rotating the scope cylinder, which enables a larger field of view, but makes the scope calibration process more difficult. The calibration is a critical step for incorporating oblique scope into computer assisted surgical procedures (robotics, navigation, augmented reality), though few calibration methods of oblique endoscopes has been developed. Yamaguchi et al. [1] first modelled and calibrated the oblique scope. They directly tracked the camera head and formulated the scope cylinder’s rotation to the camera model as an extrinsic parameter. Their method requires five additional parameters to be estimated. In this work, we track the scope cylinder instead. Since the rotation of the camera head with respect to the cylinder only causes the rotation of the image plane, less parameter needs to be estimated. Experiments demonstrate the ease, simplicity and accuracy of our method.

Over the last decade, orthopaedics has been one of the most active and diverse areas of development in computer-assisted surgery. Othopaedics has been a specially challenging area of development as many orthopaedic surgeons consider the outcomes of conventional procedures generally successful. There is significant pressure to improve the efficiency and ergonomics, reduce cost and dependence on more expensive medical imaging modalities, and simplify the use and interfaces. Increasing emphasis on less invasive and minimally invasive procedures could give a significant boost to the adoption of computer-assisted surgery. In this paper, we present the overview of different approaches using a classification scheme that relies on two important criteria: 1) the autonomy of clinical action permitted to the system and 2) the imaging requirements.