Game Development Reference
performer. A major disadvantage is the requirement for a dedicated studio
or a high set-up time and the high cost of the systems.
Magnetic motion capture uses the movement of a sensor in a magnetic
field. The sensors provide both position and orientation. An actor is
provided with a suit that houses several sensors, usually located on a
major body part (bicep, forearm, hand, etc.). The actor then performs
within the confines of three scanning devices. Software then calculates
the location and orientation of each sensor. If the software is also provided
with knowledge of the sensors' hierarchy as applied to the actor, a very
effective motion capture solution can be determined. Magnetic motion
capture suffers because the actors are limited to the region between the
scanners and are encumbered by sensors and either cables or wireless
transmitters. The scanning region is significantly less than the area
available to optical capture. However, a major benefit of magnetic capture
over optical is the lack of occlusion. Each sensor can be relied on to
provide an uninterrupted stream of good data.
A mechanical suit is a rigid arrangement of joints that are located around
the actor. Unlike the previous optical and magnetic captures, which
Figure 12.4 Magnetic motion capture.