Hardware Influences

Before I go into the details of what our multitouch display will look like, I want to take the time to credit all the hardware designs online that have influenced the final specifications.


Probably the most influential project I found was from Charless Fowlkes on instructables.com describing step by step how to build an FTIR multitouch display (see next paragraph).  Fowlkes not only showed a simple proof of concept, but demonstrated that the costs of building such a display were not much at all.  After seeing a cheap, simple, functional multitouch display, I was encouraged to bring the technology to the School of Engineering and Applied Science at Miami University.


Thanks to Fowlkes, I managed to learn about the concept of frustrated total internal reflection (FTIR) and how it can be used to create multitouch displays.  You can shine infrared light through a piece of acrylic and due to the angle that the infrared light hits the surface of the acrylic, it will remain entirely inside the acrylic.  Only after someone touches the acrylic and scatters the infrared light downward does the light break the surface of the acrylic.  When this happens, you can detect where the touch is located by using a camera with an infrared filter. See J. Y. Han's original research for more details.  Also, Christian Moore has some amazing diagrams that really help illustrate the process.


After seeing Charless Fowlkes and J. Y. Han's research, I discovered a number of other great and interesting multitouch projects built using FTIR - particularly among those in the Natural User Interface (NUI) Group.  I thought that building a multitouch table would be straight-forward enough until I saw the brilliance and creativity of other groups.  Instead of using a projector as many multitouch systems do, Alex Tan showed how you could disassemble and use an LCD display instead.  Also, user jbolton built a huge multitouch sphere, and Hiep Truong built a portable LLP display that can fit in a suitcase!


Finally, TouchFactors demonstrated even quicker and cheaper methods of building a FTIR display by using infrared LED strips, a single piece of polished acrylic, and Rosco Grey.  The results they got were incredible and among the most promising designs for our particular multitouch project.


So, from all these influences, we can pick and choose what features make it into our final design.  In the next post, I'll discuss the specifics of our hardware design!