Concept

Multi-touch interfaces have been around since a couple of years. It is relatively a new area of HCI, with continued research and development. A number of table-based products have been introduced in the market, and more are coming every year.

The concept behind our project was to develop such a multi-touch table for a home environment. Since a table acts as a host to different household objects, these objects can have some kind of interaction with the table having multi-touch interface.

Design Process

The project was built by using a table frame with a reflecting acrylic as its tabletop, which was used to project the image from a computer placed inside the table. A video projector beams images on the computer screen over the acrylic, and a modified camera detects the reflected infrared light from the objects placed over the table and the fingers touching the surface. Infrared LED's are placed inside to light up the screen from below, so any object that touches the screen reflects back the IR light which this time are coded as blobs of special fiducial marks or finger prints for further analysis to complete the goal interaction. An Arduino circuit is programmed to control the IR light illumination and diffusion from the LED's. Mirrors are used to enlarge and fit the image over the screen, through increasing the distance between the projector and the acrylic.

Software was developed using Processing - an open-source programming language, along with ReacTIVision, an open-source library for multi-touch interfaces. Interaction applications were designed for a coffee-cup, a TV remote control, and a few cards representing music tracks.