Game Development Reference
In-Depth Information
Manual motor interfaces
Philippe Fuchs
Contributor: Hervé Mathieu
7.1.1 Location sensor and dataglove
This chapter deals with motor interfaces that are specifically dedicated to the hand.
In the real world, grasping an object by hand is a phenomenon that brings into play,
even if subconsciously, complex processes at the sensorimotor and cognitive levels. The
motor interface that seems to be the most suitable, in theory, is the dataglove which
can measure hand and finger movements. A lot of designers have used the dataglove
as a tool to handle virtual objects without much thought. Handling is one of the four
categories of “Virtual Behavioural Primitives'' (VBPs), in other words, the problem of
selecting the handling interface is common. If we think about this, we observe that it is
often a question of being able to easily move in object rotation and translation motion
(from 2 to 6 DOF). Effective grasping of the object is often simplistic: the object is
either grasped or released. These frequent instances do not require using a dataglove.
A simple tracker suffices to indicate the movements of the object, which is gripped
and released by a simple binary control. This command can be given by a button or
by simply taking a virtual cursor on the screen closer to the object to be handled. We
thus benefit from the simplicity of the laws of the virtual world, as compared to the
real world. This explains the fact that not many applications really need a dataglove,
and that their commercial development is relatively slow. The designer of a virtual
reality application should thus always ask himself: is it necessary to use a dataglove?
Wouldn't a tracker suffice?
7.1.2 Location sensor and command interface
This does not always involve handling an object in a virtual environment. In the chapter
discussing trackers, we indicated that they can be used to:
either handle a virtual object;
or direct a cursor in a virtual environment.
In the first case, the user acts “ naturally '' in the virtual world; the tracker just follows
the movement of his hand. The second case generally involves commanding a specific
action: for example, moving in the virtual world by indicating a direction, pointing on
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