A flexible markerless registration method for video augmented reality

This paper proposes a flexible, markerless registration method that addresses the problem of realistic virtual object placement at any position in a video sequence. The registration consists of two steps: four points are specified by the user to build the world coordinate system, where the virtual object is rendered. A self-calibration camera tracking algorithm is then proposed to recover the camera viewpoint frame-by-frame, such that the virtual object can be dynamically and correctly rendered according to camera movement. The proposed registration method needs no reference fiducials, knowledge of camera parameters or the user environment, where the virtual object can be placed in any environment even without any distinct features. Experimental evaluations demonstrate low errors for several camera motion rotations around the X and Y axes for the self-calibration algorithm. Finally, virtual object rendering applications in different user environments are evaluated.