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Arhrrrr - An AR Shooter without Magic Symbols

Magic Symbol technology is the cornerstone of augmented reality devices, so to stumble across an application that at first glance doesn't use them, seems incredible. What's more the same app interacts with physical objects at a previously unprecedented level - and that is the secret to its success.

ARhrrrr is an augmented reality shooter for mobile camera-phones such as the iPhone, Zune, PSP portable, or Samsung's Nvidia powered cameraphone. It uses a printed out map, that doesn't at first seem to contain any magic symbols. Instead it contains the tops of some buildings, each one different, and a set of converging streets below them, Then, when you move over the map, the buildings leap out at you into 3D. The rooftops themselves become magic symbols. Each is different to tell the phone which one to render where. It also means you can move the viewpoint about however you like, with only part of the map visible at any one time - the processor automatically works out which part of the map you are looking at, by the portion visible in the screen.

This technology on its own has immediate implications for applications in virtual worlds - print out a map of the world and zoom over it in your living room, for example. However, Arhrrrr goers further than that, for it is at heart a game. The map is a towm, and you are playing the part of a helicopter gunship during a zombie invasion.

Civilians are trapped in the town, and must escape before the zombies eat them. From your helicopter, you must shoot the zombies to clear the path for the civilians to get out. The zombies fight back against your hail of bullets, directed wherever you point on the touchscreen (or by buttons where you are focussing, if the device has no touchscreen). They fight back by breaking off their own limbs and hurling them at the helicopter. To dodge, move the phone. As fast or slow as you like, waggle it around in 3D space. So long as part of the map is visible, your position and distance can be calculated in real-time, thanks to the level of machine vision algorithms developed for the application.

These algorithms, along with the demonstration game, were developed by Georgia Tech Augmented Environments Lab and the Savannah College of Art. The algorithms will filter down into other products once they are perfected of course, Arhrrr is just to show the level of flexibility and power thus far achieved.

As a final twist to the concept of magic symbols, the app will recognise one unusual type. It has been coded to recognise a skittle - yes, the sweet. Place one on the board, anywhere, and the game will recognise what it is, matching its size and shape to a database, and enter it in the game as a bomb. Shoot it with the helicopter and it 'explodes', that is to say, its physically still there, but an explosion radiates out from it, killing all the zombies in its path. Try this with any object that doesn't look like a skittle, and nothing happens. The app then is fully capable of accepting a 3D shape as a magic symbol.

Further work in this area will be monitored with a keen eye.


Augmented Reality Basics: Magic Symbol


Uncertainty Boundary for Complex Objects in AR (PDF)

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