ABSTRACT
The touchscreen plays a major role in user interaction on mobile devices. Al-
though some of these systems come with high-level APIs that could be used by
the programmer to detect gestures, others provide just raw access to the samples
read from the hardware. This chapter illustrates a mathematical framework that
can be used to estimate the motion and position of the input pointer on screen
(see Figure 1.1). An application for controlling the position of a camera in a
three-dimensional spherical coordinate system is presented as an usage example.
Let us approach the problem of estimating the motion on screen, given a set of
samples described by three values:
