Interactive input system and method

An interactive input system comprises an optical waveguide, a radiation source directing radiation into the optical waveguide, the radiation undergoing total internal reflection within the optical waveguide in response to at least one touch input on a surface of the optical waveguide. At least one imaging device is positioned adjacent to the waveguide, the at least one imaging device having a field of view looking inside the optical waveguide and capturing image frames thereof. Processing structure processes the image frames captured by the at least one imaging device to determine a location of the at least one touch input based on a frequency of reflections of the radiation appearing in the image frame.