turn (horizontal) was calculated by determining the angle of displacement the hand would

make from a central vertical line.

 3.3 Putting it all Together

 VRPN was used to connect and transfer text messages between the tracking

system and the rendering system as well as between each rendering system. The tracking

system sends a text message containing the two-dimensional coordinates for each color

detected along with the width and height of the image in pixels. The rendering system

receives these values and, combined with the values from the second tracking system,

uses Tsai's algorithm for recovering the three-dimensional coordinates [24].

 Once calibration has finished and the actors are accustomed to using the system,

the tracked data is shared between rendering systems via VRPN text messages. The text

message contains the two angles for each shoulder and for the neck, the bend angle for

the elbow, and the speaking state. The speaking state determines which actor is currently

speaking; this is used with the lip-syncing and virtual script systems.

 Voice acting is an important aspect of rehearsal. Therefore it was necessary to

implement a system that allowed the actors to transmit their voice to their partner.

Headsets with built-in microphones were used. The headsets had a behind-the-neck

design so they would not interfere with the forehead strap. Voice was transmitted using

DirectPlay.

 Instead of using a traditional physical script, a virtual script system allowed the

actors to read their lines without having to look away from the display. This system

displayed the actor' s current line on the bottom of the screen when their speaking state is

true. Incorporating the virtual script system introduced the problem of determining when