Biomedical Engineering Reference
In-Depth Information
Interested readers are referred to Bowman et al. [
5
], and the IEEE Symposium on
3D User Interfaces, where new devices are introduced every year.
We start with the simplest device: a button. The very simplest travel interfaces use
one or more buttons on a device that the user holds. Indeed, many position-tracking
systems include a hand-held device with buttons as standard. A button can be used to
indicate that movement should be effected, and the direction of the movement might
depend on the orientation of a tracker.
This is all one needs if the display fully surrounds the user (i.e., the field of
regard is 360
◦
), but otherwise some control is needed to rotate the viewpoint in
the environment. One could achieve this with a button and a gesture to point, but
simpler and possibly easier and more intuitive for the user is to provide a joystick
(see Fig.
7.12
, Right).
There is a broad range of devices that are common with desktop computers and can
be used or customized to use in an immersive setup. A wireless handheld gyroscopic
mouse is a common choice. As noted previously the gyroscope is only a rotational
control, so it is not sufficient to give an accurately registered direction, but a position
tracker can be attached.
Assemblies of controls can become quite complicated. Trackers and buttons can
be embedded in props such as weapons or sports equipment. While such props
have long been common in video games, Hinckley et al. proposed using them for
other applications, including embedding a tracker in a doll's head to aid with a
neurosurgical visualisation [
11
]. It may be that the task includes complex controls
beyond travel, selection and manipulation of objects. In this case a controller might
be custom built or a controller with a wide range of control patterns might be used.
For example, the cubic mouse [
10
] is a tracked cube with three orthogonal rods
passing through it.
For more complex user interfaces using multiple dynamic interfaces such as
menus, an obvious and common choice is to utilize a mobile device such as a tablet
or smartphone as a control device. This can display virtual buttons, virtual sliders,
and other controls to facilitate travel. A common use of mobile devices is to act as a
secondary data display, by providing maps, e.g., [
23
], text or numeric information,
or alternate views of the virtual world. A metaphor that can be used is the concept
of the magic lens or 3D magic lens [
39
] through which the 3D world can be seen in
a different way. This then can act as an interface to tasks in the VE, including travel.
An example of the type of more complex travel interface that can be built with
such devices is the World-in-Miniature (WIM) technique, which creates a hand-held
miniature map of the world that users can use to move themselves around the VE [
26
].
Such devices don't need to be physical devices; they can be simulations of physical
devices or other representations of virtual controls. For example, the
virtual tricorder
and
pen-and-tablet
approaches embed virtual controls in the 3D environment that
are anchored to the tracked position of a hand-held device [
4
,
35
,
46
]. These controls
can be used for a variety of tasks, including travel.
Our final category of device is hybrid devices. This is a catchall for novel and
interesting technologies that can be used to control travel. For travel techniques, an
obvious place to put the technology is on the floor. Consumer games utilize devices
