Any object in the VR World needs three coordinates to exist (X,Y,Z).
To manipulate the object the system has to specify three angles or the pitch, roll and yaw.
These are called the six degrees of freedom(6 DOF). There are five major group of systems that measure the translation or rotation for the Virtual World, these groups are called the Tracker Technology systems. The first of the systems is a mechanical device that uses rigid rods to measure the rotation of a joint. The second system sets up an electromagnetic field that calculates the position of receivers worn on the head and hands.
Another system uses an infra-red light direct towards an object where the distance is calculated.
The fourth system uses sound that is sent as a signal to microphones placed at points on the body,
the time is recorded and the distance is calculated.
The last system uses gyroscopes to measure changes in rotation about
1, 2 or 3 axes. Though none of these systems has been proven to be completely accurate there
is certain to be some sort of lag in Virtual Space.