Instead of computely redacting the real world as a Virtual Reality(VR) system does

the user can see computer-generated 3D model superimposed on the real world with an Augmented Reality(AR) system. One of the key technologies of AR is the real-time 3D registration of objects in the real world. This paper describes a vision-based method for AR registration and its application in an AR system with See-Through Head Mounted Display(STHMD). The scheme has a simple structure

which employs one color CCD camera and several mark points with different colors. The real world coordinates of the markers are known

and their screen coordinates are obtained through color filtering of the input video stream. If all the markers are successfully tracked

a translation matrix and an orientation matrix can be uniquely determined using projective transform relations. The algorithm requires only linear equation solving with small calculation errors and little computation time consumption. Therefore it has good real-time performance characteristics and can be employed with either graphic workstations or ordinary PCs. The method can work at long ranges and is applicable to outdoor augmented reality systems.