Touchware: A Software based Implementation for High Resolution Multi-touch Applications

Finger pointing on touch screens is very intuitive to use. However, for most capacitive multi-touch devices, it may suffer from the nature of direct input since the size of human fingers and the lack of sensing precision can make absolute positioning on touch screen difficult. In this paper we present Touchware, a software based implementation to overcome limitations and to provide support for the development of multi-touch applications for rich input modalities. We introduce the maxima based clustering algorithm to detect and distinguish single/multiple touches, weight based geometric center algorithm to calculate a precise interpolated (x, y) coordinate for each finger touch, and first contact based decision with sniper for ghost pattern (symmetric pattern) elimination. We show how the techniques can be successfully used for single touch applications, such as click, scroll, flick, and multi-touch applications such as zoom in/out and rotation.