Game Development Reference
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Figure 7.7 Hall effect dataglove
for the whole glove. Each rotation of a phalanx is measured by a Hall effect sensor
placed at the mechanical articulation of the glove. The resolution (12 bits) of the
measurements is given at one-tenth of the degree. These characteristics are related to
the rotations of the articulations of the mechanical structure, but not to those of the
phalanxes. The measurements are read at the frequency of 75Hz. An adaptation to
the varying sizes of the user's hand is planned. The weight (approx. 400 g) and overall
dimensions are significant disadvantages of this type of interface (Figure 7.7).
7.2.5 Special case: binary command glove
The gloves that we just presented help to measure finger deformations. This is not the
case with the pair of “Pinch Glove'', which only prompts the user to send a series of
binary commands , associated to the position of the hand, as there is a tracker on each
glove in the same way as the other datagloves. The operating principle of this glove is
based on the following phenomenon: the contact between two or more fingers creates
a conducting loop (closed electric circuit), which enables a series of virtual pinching
gestures that can be used in the applications (Figure 7.8). The information is sent to
the control PC as soon as the electrical contact is validated. Theoretically, it is possible
to command more than 1000 gestures, but the user must know them!
7.2.6 Conclusion
We have just seen the three main dataglove categories, but let's not forget that it
is possible to follow hand and finger movements by image processing. Researchers
have started to detect hand movements of persons in a public place. For their own
information, these persons must indicate displayed menus by pointing with their hand
to a large screen. In this case, it is not desirable to ask persons to use a glove to only
point on the screen. The solution by image processing (10 per second) is justified and
provides a first approach to natural and transparent control, in spite of the algorithmic
difficulties. The two cameras are placed carefully, above and on the side, making it
possible to locate the pointer finger and its direction. Other researchers detect the
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