A method of calibrating a circular portion of an object, such as to determine the center point thereof, is provided. The method comprising determining spatial coordinates of at least two points on a circumferential edge of the circular portion of the object, and calculating the center point of the circular portion using the spatial coordinates of the two points and a geometric parameter representative of the diameter of the circular portion. A calibration device and system are also provided for use with a computer tracking system in order to calibrate such an object having a circular portion.