US Patent 7369101 Calibrating real and virtual views

A method for calibrating real and virtual views includes tracking a calibration screen, wherein a real reference point, generated by a real reference point generator, is projected on the calibration screen, aligning a view of a virtual reference point to a view of the real reference point in a display, wherein the real reference point generator and the display have a fixed relative position, determining a point correspondence between the virtual reference point and the real reference point, and determining one or more parameters for rendering a virtual object in the real scene.