The Tilt Menu can be useful in applications, such as
freeform drawing and online synchronous sketch
recognition. If the application requires freeform drawing, it
is worthwhile to explore one-handed techniques that have
the inherent advantage of merging command selection and
direct manipulation [12]. However, current one-handed
techniques all face similar lim
itations wherein the user has
to move the pen tip in order to make a selection. Thus there
is ambiguity regarding whether the selection stroke is part
of the drawing or the drawing has to be started at some
point away from the initial location where the technique
was initiated. Comparing to other one-handed techniques,
the Tilt Menu can smoothly merge command selection and
freeform drawing simultaneously by using the pen’s 3D
orientation information to perform selection tasks.
Continuous interaction is a very important feature in pen-
based user interfaces [14]. In
an online synchronous sketch
recognition system, the recognition procedure is
simultaneously run with the drawing action [3] [29] [19],
thus helping users know whether their intentions have been
understood correctly or not. If the current recognition result
is ambiguous, users can correct the recognition results via
interaction in real time. Therefore, users have to perform
some selection tasks simultane
ously with sketching when
the current recognition result is ambiguous. However, with
the current techniques, such as SmartGuides [1] or
automatic constrains generation [24], users have to cancel
current drawing task to perform the selection. In such
situations, the Tilt Menu can simultaneously generate the
secondary input while sketching with a pen tip without
having to use the second hand or another device.
Additionally, Tilt Menus can be used to enhance traditional
context-aware menu techniques such as pie or marking
menus [19] [32]. The 3D orientation information may be
added to existing pen interaction techniques without
interfering with interactions.
By adding the 3D orientation
information to the technique, the Tilt Menu makes the pen a
kind of 3D interaction device.