Biomedical Engineering Reference
In-Depth Information
Table 16.1
A proposed set of gestures for natural locomotion
Task Technique
Translation (local) Normal walking
Translation (extended) Running in place
Orientation Shoulder steering
Combat Punch and kick
Sliding Duck
Balance Arms out and leaning
Climb pole Repeated placement of fists over the other
Climb up (from hang) Arms up and pull down
Climb up (ladder) Alternating arm pull-down
Jump (low) Hop, no arms
Jump (medium) Hop, arms out front
Jump (high) Hop, arms up
These can form the starting points for larger or smaller gesture sets
Context
. Understand the role that context plays in the interface. A gesture for jump
may indicate climb when in front of a ladder. At a minimum, understand how context
can play a role in mutually disambiguating [
14
] between multiple outcomes. While
gestures may look similar, their use may not be and this becomes a dimension of
differentiation that can be incorporated.
“Waggling” Motions
. “Waggling” or “cheating” motions are commonly used in
Wiimote games due to the devices not properly recognizing the absolute motions
of the user and accepting more chaotic or less “weighty” versions of the gesture.
So, instead of performing a realistic punching gesture, a user might tap the Wiimote
forward which the game recognizes as a punch. While this might seem a limitation,
these types of waggling motions have a place in some interfaces when the purpose
is not for exercise or training, but fun or utility. The result are games winnable by
simply moving the device randomly about, but that are still fun and can be played for
longer periods of time. When building recognizers, make sure to support the purpose
of the gesture and not just the absolute form.
Compensation by “Story”
. Whenever possible, the easiest means of compensating
for input hardware limitations is through the use of story. By “use of story,” we mean
that by careful manipulation of the user's tasks and their goals, the shortcomings
of the technology can be avoided. For example in augmented reality, where perfect
registration to the real world is very difficult, use NPC ghosts because we expect
ghosts to float around, be translucent and pass through walls. For a hard to recognize
gesture, create a story element that requires the user to perform some easily recog-
nized gesture first to create context or allow the recognizer to make an assumption.
This is common in Wii gaming where accuracy is second to enjoyment and playa-
bility. To compensate for the Wiimote's drift, games require the user to return to a
known position where the gravity vector or position can be assumed. So, Wii Sports
Resort's Frisbee requires you to point at a disk right before you throw it, We Cheer
