For my master’s thesis and for Tapspace project, I wanted to study algorithms needed in two dimensional touch manipulation. The problem was that most pinch-zoom, rotate, and similar two-finger gestures fail if a third finger comes into play and touches the screen. In the thesis a set of algorithms are created that gracefully deal with any number of fingers and in computationally fast manner.
See the thesis at: Advanced algorithms for manipulating 2D objects on touch screens
Cite the paper for example as follows: Palén, A.: Advanced algorithms for manipulating 2D objects on touch screens. Master’s thesis, Tampere University of Technology (2016). Available at http://urn.fi/URN:NBN:fi:tty-201605264186