Technological Research

Using information from Seb's email, I found countless articles and build guides around capturing touch events in interactive applications. A popular solution is to use FTIR; it's a cheap and effective solution, which has become very popular!

Frustrated Total Internal Reflection
FTIR

Infrared light is shined into the side of an acrylic panel (most often by shining IR LEDs on the sides of the acrylic). The light is trapped inside the acrylic by internal reflection. When a finger touches the acrylic surface this light is 'frustrated' causing the light to scatter downwards where it is picked up by an infrared [sensitive] camera.

Source: http://nuigroup.com/forums/viewthread/1982


Click image to enlarge

Parts:

• Acrylic, Polycarbonate or Plexiglass
• Infrared LEDs (or similar IR light source)
• Compliant Surface (Silicone Rubber E.G. Sorta Clear 40, Elastosil, Lexel, etc.)
• Projection Surface (Rosco Grey, Vellum, Mylar, other, etc.)
• Infrared Camera or Modified Webcam

Using the feed from a webcam, we can register glowing white blobs, from finger contact, using Processing or a similar langauge. These only appear once the surface has been touched; even the location of these blobs can be tracked, opening up the possibility for a gesture controlled interface.

Select Resources

Building an FTIR-based Multi-Touch surface

• http://sethsandler.com/multitouch/
• http://modin.yuri.at/teaching/TangibleWorkshop/papers/multitouch.pdf
• http://research.microsoft.com/pubs/132465/fulltext.pdf

Using the Kinect to replace FTIR technology

• http://nuigroup.com/forums/viewthread/11412/
• http://research.microsoft.com/en-us/um/people/awilson/publications/WilsonITS2010/WilsonITS2010.pdf