The Virtual Haptic Radar (VHR) is a wearable device helping actors become aware of the presence of invisible virtual objects in their path when evolving in a virtual studio (such as a "bluescreen" filming stage). The VHR is a natural extension of the Haptic Radar (HR) and its principle in the realm of virtual reality. While each module of the HR had a small vibrator and a rangefinder to measure distance to real obstacles, the VHR module lacks the rangefinder but accommodates instead a (cheap) ultrasound-based indoor positioning system that gives it the ability to know exactly where it is situated relatively to an external frame of reference. Each module maintains a simplified 3d map of the current virtual scene that can be updated wirelessly. If the module founds that its own position is inside the force field of a virtual object, it will vibrate.

It is important to understand that the requirements for our tracking system are fundamentally different from that of traditional (optical or magnetic based) mo-cap systems: (1) each VHR module must know its own position in the room, independently from the others and without the need for a centralized computer; (2) the tracker must be inexpensive in order to enable scalability; (3) the modules must be invisible to the cameras (in particular, they should not emit or reflect visible light); and (4) interference should be minimal or inexistent if one wants tens of modules to work simultaneously (this puts aside most non-sophisticated magnetic trackers).