Augmented Reality has Gained Gravity

Here’s the latest AR dish from Ohan Oda and Steve Feiner at Columbia University‘s Computer Graphics and User Interfaces Lab: an augmented reality marble game that uses gravity as a game controller. No iPhone required.

See the video and recipe after the jump.

The player wears a video-see-through head-worn display, and tilts and translates a tracked board to guide a virtual “marble” (actually, more like a little rubber ball) through a dynamic maze of obstacles. Gravity in the game always points in the correct direction, no matter how the player’s head and board are oriented relative to each other. This is possible because the game uses both optical marker tracking and a separate head-tracker built into the head-worn display. The optical marker tracker relies on a camera on the head-worn display to determine the board’s relative position and orientation. The built-in head tracker determines which way is “down,” which the game uses, in turn, to compute the true “down” direction for the board.

The ingredients include:

  1. Goblin XNA, an open-source infrastructure for AR apps, that Ohan Oda has built on Microsoft XNA Game Studio 3.0 and can be downloaded.
  2. Physics Engine –  Newton Game Dynamics.
  3. ALVAR Optical tracking engine by VTT Research Center in Finland
  4. Vuzix iWear VR920 head-worn display and CamAR camera
  5. A Paper board (can’t be downloaded – you need to leave home and go to a paper store)

Can you guess the secret sauce for this lovely AR dish?

Go ahead – try this at home!

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7 Responses

  1. Wow, they’ve done a nice job with that. Reminds me of that table game with the holes in it that you have to navigate your ball through without it falling through the holes. Frustrating game. I like their version better, but it shows you the possibilities.

    Maybe they should do a pinball game next with some inventive elements to the game. They’d only be limited by the size of their imagination. :)

  2. Excellent tracking performance. Is it more due to the camera used (CamAR), or due to ALVAR?

  3. pretty cool demo. games like these when programmed for mobile devices like iPhone, look to be the first major AR market.

  4. Thats really nicely done.

  5. Thanks for the comments! In answer to rouli, tracking performance is due to VTT’s ALVAR optical tracking package, which will be integrated into our next release of Goblin XNA. (CamAR is a USB 2.0 camera that is molded to fit the front of the VR920. Vuzix can tell you whether they will bundle CamAR with any tracking software when it’s released, but we were just given it as a camera.) As our youtube description mentioned, we are also using the orientation tracker built into the VR920 to determine the direction of gravity. However, that affects only gameplay, not tracking.

  6. […] Goblin XNA: Infrastructure for Augmented Reality (Columbia University) […]

  7. […] “an augmented reality marble game that uses gravity as a game controller” – see Ori Inbar’s write up here.  It was a very compelling experience and I have to say I didn’t really notice the […]

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