Virtual reality offers completely new possibilities for collaborative work over distributed environments. To enable collaborative work, it is necessary that both, virtual objects as well as the other users, can be seen simultaneously in real-time. A novel technique is necessary to overcome the contradiction of darkness and light for image projection and video acquisition, respectively. A stroboscopic light and a camera system are added to the existing VR-system and a few modification are made

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... existing shutter glasses. In such a solution, the method of projection in the VR-system remains unmodified. This paper describes how to resolve this contradiction with the constraint to make as few changes as possible to existing VR-systems. Furthermore the timing of the different devices is discussed.