Surgical navigation system: 3D display system with see-through visor； a tracking system for real-time tracking of: surgeon's head, see-through visor, patient anatomy and surgical instrument to provide current position and orientation data； a source of an operative plan, a patient anatomy data and a virtual surgical instrument model； a surgical navigation image generator to generate a surgical navigation image with a three-dimensional image representing simultaneously a virtual image of the surgical instrument corresponding to the current position and orientation of the surgical instrument and a virtual image of the surgical instrument, the see-through visor, the patient anatomy and the surgical instrument； the 3D display system configured to show the surgical navigation image at the see-through visor, such that an augmented reality image collocated with the patient anatomy in the surgical field underneath the see-through visor is visible to a viewer looking from above the see-through visor towards the surgical field.
