Multi-Touch Surfaces: A Technical Guide

Multi-touch interaction with computationally enhanced surfaces has received considerable recent attention. Approaches to the implementation of multi-touch interaction such as Frustrated Total Internal Reflection (FTIR) and Diffused Illumination (DI) have allowed for the low cost development of such surfaces, leading to a number of technology and application innovations. Although many of these techniques have been presented in an academic setting, the practicalities of building a high quality multi-touch enabled surface, both in terms of the software and hardware, are not trivial. This document aims to summarize the knowledge and experience of developers of multi-touch technology who gathered at the Bootcamp on Construction & Implementation of Optical Multi-touch Surfaces at Tabletop 2008 in Amsterdam, and seeks to provide hints and practical advice to people seeking to “build your own” multi-touch surface. We mostly focus on technical aspects that are important in the construction of optical multi-touch surfaces, including: infrared illumination, silicone compliant surfaces, projection screens, cameras, filters, and projectors. In addition, we outline how to integrate this hardware to allow users to create a solid multi-touch surface, and provide an overview of existing software libraries for the implementation of multi-touch applications. In addition, we discuss the problem of latency introduced by the different parts of the system. A brief description of most of the common technologies to realize (multi-) touch surfaces is provided; however, the main focus is on those that utilise optical approaches.