When you were a kid, perhaps you and your friends played with flashlights, chasing each other's light spots across the wall - if you were born within the past 20 years, just substitute the term "laser pointers" for "flashlights." In either case ... wouldn't it have been neat if those spots of light came to life when they met, and fought with each other? That's the type of thing that's now possible with the prototype SidebySide system, developed by Disney Research, Pittsburgh, and Carnegie Mellon University. It enables animated images from two separate handheld projectors to interact with each other on any surface.
Each of the units incorporates not only a pico projector, but also visible and infrared light emitters, a camera, a ranging sensor and an inertial measurement unit. The users see only the animated visible light images, while the cameras read each other's image marker codes, projected only in infrared. When the units see that their markers are nearing one another, they each cause their own animated images to react accordingly.
The inertial measurement units let the devices know the direction in which their beams are being moved by the user, while the ranging sensors tell them how close they are to the projection surface, both of which can also affect what the animated images do.
Demo applications for SidebySide mostly include a number of simple games so far, including ones where boxers spar with one another, an airplane tries to net a hostile gorilla, and a cannon-user attempts to shoot apart a stack of bricks. The Disney/Carnegie Mellon team have also demonstrated some more practical applications, however - they have shown how the system could be used to rotate and explore 3D models, select and transfer files between devices, and teach vocabulary to children.
The video below shows the system in use, and provides some more technical details.