I need someone to explain this to me.

IR glass level detection

[Johnny Lee]‘s colleague [Paul Dietz] has done some interesting work using interactive tables. He’s specifically researched how to determine how full a drink glass is. In the video above, he’s using Microsoft’s Surface, but this technique should work with any IR camera based multitouch table. Determining the drink level requires custom glassware that has a small prism inside. When the liquid level is above the prism, light passes through, but when it’s below the top it reflects more IR light back into the table. Using this information, restaurant staff could serve drinks in a more efficient manner.

[Paul] has worked on another project that uses RFID and capacitive sensing to a similar effect.