Working principle behind this audio touch-table ?


I want to replicate something similar to this :

Not on the audio functionality, I just want some attractors with well defined edges (=the cubes or whatever you put on the table) and play around with visuals.

I've thought about it and can't find a tenable hardware solution... Only solution I see is with an IR camera+computer vision to determine edges, but even then I doubt it'd be so responsive/well detailed.

In your opitnion how can the edges, positions and rotations be so well defined in the above example ? Thanks.

what do the people on that forum say about it?

I would assume they would know more about it than anyone.

Here is a link from the react table that was mentioned in your link.


this is from how-stuff-works

To analyze the positions of the blocks in relation to each other, the reactable uses a computer vision (CV) system located under the tabletop surface. The CV setup is completely hidden within the machine and consists mainly of two important tools -- a camera and a projector.
Both the camera and projector point up toward the bottom of the tabletop, but they each serve a different purpose. The camera, which runs on a special vision engine called reacTIVision, looks up at the blocks and analyzes several factors:

  • ­Which sides of the blocks are facing down on the table
  • Where the blocks are in relation to the table's center
  • Where the blocks are in relation to other blocks
  • How the blocks are positioned around their own axis
  • Any other tangible adjustments made on the table's surface that might alter pitch, filters and so forth

The reacTIVision engine takes all of these positions into account, analyzes the space and sends the information to a connection manager, which does two things simultaneously. First, it passes the reacTIVision's information to an audio synthesizer, which creates the sounds the musicians are attempting to play and pumps the music out to an output source. At the same time, the connection manager sends that same information to the projector, which also points up toward the underside of the tabletop. This projector isn't taking in information like the reacTIVision camera; instead, it paints the animations onto the blue, translucent tabletop, providing the players and spectators with the appropriate visual cues to match the music coming out.