Display systems and registration methods for augmented reality applications

Introductions are given to various display systems and corresponding registration methods developed and realized at Beijing Institute of Technology for augmented reality applications. An interactive projection system is used in a theatrical performance, and the registration between the virtual scene (projected image) and the real objects (dancers) is realized through a video camera working in the near infrared waveband. An ultra-light wide-angle head-mounted display system is designed for an interactive exhibition item in a scientific museum, and a multi-user six-degree-of-freedom tracking system is developed for the indoor registration, which uses infrared markers projected on the ceiling and a camera fixed on top of each head-mounted display. A fixed-position viewing system is developed for the on-site digital reconstruction of a historical site, which provides visitors with the visualization of the original magnificent buildings on the natural field of the ruins. The azimuth and pitch of the viewing system are detected by two rotary encoders. A volumetric 3D display based on multi-angle projection is applied in a navigation system for endoscopic sinus surgery. A 3D digital scanner is employed to scan the skin on the patient's head for the alignment between the patient and the 3D model from his CT or MRI images. The registration of the surgical tool is also achieved by optical means through tracking cameras.