AR isn't just about flashing Google Project Glass alerts up in your line of sight, it's also about getting your hands dirty with some mediated reality thanks to an Augmented Reality Sandbox project by UC Davis. The handiwork of researchers at the W.M. Keck Center for Active Visualization in the Earth Sciences, the digital sandbox uses a projector and Microsoft Kinect sensor to track the contours of the sand and overlay a real-time topographic map complete with virtual water flow.
The Kinect side uses the sensor bar to capture changes in the sand at 30fps, tracking how the user piles it up or creates troughs, and then projecting customizable color maps on top. A one second delay is introduced so as to filter out the movements of the user themselves, among other things.
As for the water, that uses GPU acceleration to figure out in real-time where, exactly, real waterways would flow around the topography. The PC - a Core i7 with NVIDIA GeForce 580 video card - crunches the scene as if the water was flowing at natural speed in a 1:100 scale factor.
All the driving code will eventually be released under the GNU license, in case you fancy giving your kids a particularly exciting sandbox to play in one day. If you're less DIY and just want to play, the team behind it say they'll be producing them for displays at the UC Davis Tahoe Environmental Research Center (TERC) and other museums.