Multitouch interface using total internal reflection

http://people.ece.cornell.edu/....land/courses/ece4760
The device relies on the concept of frustrated total internal reflection (FTIR) to detect user motion on an acrylic surface. Using a camera system and infrared LED setup, these blobs of infrared light are read into the microprocessor and detected using a dynamic thresholding algorithm. The data is streamed over serial using the FT232R USB connection and a compatible program on the user interface emulates the turntable motion. We have also written up additional code that uses the blob tracking for simple mouse movement. Using MATLAB's powerful image processing library, more complex interactions can be coded.