Game Development Reference
Figure 7.3 5DT DataGlove optical dataglove. (Illustration: SimTeam, with permission)
The advantage of these interfaces is their low volume and light weight, which
provides a certain level of comfort. Today, companies offer fibre optic datagloves for
PC-compatible computers at a modest price. A glove can have a sensor per finger, with
a resolution of eight bits, and the measurements are transmitted 25 times per second.
The gloves of the Fifth Dimension company provide the advantage of affordability
in terms of price. The operating principle is based on a fibre optic technology (for finger
flexion) coupled with 2 relative inclinometers. The lycra glove provides great flexibility.
The development of these products brings a wireless version. The two 5DT DataGlove
versions use 5 or 14 sensors. The wireless version via a radio link has a range that
extends to several meters (Figure 7.3).
7.2.2 Detection of hand movements by cameras
The hand constitutes a body part which is quite difficult to capture optically. The
hand combines a large number of degrees of freedom in a small space. Moreover, it is
necessary to manage a large number of occlusions.
The Visualeyez system of the Phoenix Technologies company is made up of three
cameras mounted on a beam. It tracks up to 512 infrared LEDs. The LEDs emit
sequentially, which renders their identification trivial. The measurement frequency is
4300Hz for a latency of 0.5ms. An instrument-embedded suit (LED, power, control
box) makes it possible to track the body. But this may seem less practical than the sys-
tems based on reflective markers. The original feature of the product is the accessories
that make it possible to follow the hand (Figure 7.4) or the face.
An Austrian university (Dorfmuller-Ulhaas & Schmalstieg, 2001) proposed an
original solution for a hand tracker. This solution is based on reflective markers in the
form of rings. These rings are set at the level of the articulation of the fingers. The rest
of the system is made up of a multi-camera system connected to infrared lighting and
a 3D model of the hand. The accuracy stated is approx. 1 millimetre for a volume of
one cubic metre. The frequency is 25Hz for a latency of approx. 100ms.