Calibration of head-mounted displays for augmented reality applications

The authors have developed "augmented reality" technology, consisting of a see-through head-mounted display, a robust, accurate position/orientation sensor, and their supporting electronics and software. Their primary goal is to apply this technology to touch labor manufacturing processes, enabling a factory worker to view index markings or instructions as if they were painted on the surface of a workpiece. In order to accurately project graphics onto specific points of a workpiece, it is necessary to have the coordinates of the workpiece, the display\´s virtual screen, the position sensor, and the user\´s eyes in the same coordinate system. The linear transformation and projection of each point to be displayed from world coordinates to virtual screen coordinates are described, and the experimental procedures for determining the correct values of the calibration parameters are characterized