1. A system facilitating on-line calibration of an imaging camera, said system comprising: a first sensor positioned with respect to an imager; a second sensor positioned with respect to a camera source; and a transmitter positioned with respect to an object to be imaged that transmits tracking data to said first and second sensors during said on-line calibration, wherein a first off-line calibration characterizes a transformation from a coordinate system of said imager to a coordinate system of said first sensor positioned with respect to said imager and a second off-line calibration characterizes a transformation from a coordinate system of said camera source to a coordinate system of said second sensor positioned with respect to said camera source, and wherein intrinsic parameters of said camera source are quantified by a transformation from the coordinate system of said imager to the coordinate system of said camera source based on said first and second off-line calibrations and said tracking data.