**2.1 Touchless as an alternative**

Touchless is an SDK that allows users to create and experience multi-touch applications. Touchless started as Mike Wasserman's college project at Columbia University. The main idea: to provide the same functionality of a multi-touch environment using cheap hardware and open-source software. All the user needs is a camera, which will track coloured markers defined by the user. Touchless is released free and open-source to the world under the Microsoft Public License (Ms-PL) on CodePlex [2]. Figure 1 is a snapshot of the major classes of the touchless SDK [2]. We modified the touchless SDK to support different types of disabilities. The details will be introduced in sections 3 and 4.

Fig. 1. Class diagram of touchless SDK [2].
