One further advantage of the gyroscope-based approach is
that it easily transfers to a “laser pointer”-like writing mode
where we assume the writing point W to be on the extension
of the phone’s longer dimension [see Fig. 7(a)]. In this case,
the hypothetical distance between the points C and the point W
determines the scale factor of the trajectory.
This mode turns out to be useful for interaction with home
cinema systems, similar to the touch pad on recent Sony settop
boxes [26], and the phone motion can either be used to control
a cursor or to handwrite characters. Handwriting can be
activated by pressing and holding a button (physical or on the
touchscreen), similar to the interaction model of a laser pointer.
Fig. 7(b) shows one example of each of the 26 English uppercase
letters written using the laser pointer mode.