A full geometric and photometric calibration method for oblique-viewing endoscopes.

Oblique-viewing endoscopes (oblique scopes) are widely used in computer assisted surgeries. The viewing direction of an oblique scope can be changed by rotating the scope cylinder; this extends the field of view, but also makes the geometric calibration process more difficult. Although few calibration methods have yet been developed, calibration is critical for the application of augmented-reality technologies such as stereo vision to procedures involving oblique scopes. Moreover, to our knowledge, no photometric calibration method has yet been introduced for endoscopes, even though such calibration is important for illumination-based visualization techniques such as shape-from-shading. In this paper, we present a complete calibration process for oblique-viewing endoscopes, estimating both geometric and photometric properties. Experimental results demonstrate that our methods are practical and accurate.