movements. The system first saved the fixed locations of each shoulder. Then, after

instructing the user to place their hands directly in front of them with their elbows fully

extended, the system determined their arm length and head height (distance from their

neck to their forehead). The system used the actor's arm length, head height, and

shoulder width constants to appropriately displace the digital character's hands and head.


Figure 3-1. A participant wearing the colored felt straps.

 Forward shoulder joint animation (vertical movement) was accomplished by

determining the angle of displacement that a line passing from the shoulder to the hand

would create from a central horizontal line. The distance from the shoulder to the hand

determines the amount of elbow bend that is required. For instance, if the hand is arm's

length away from the shoulder, the elbow wouldn't be bent at all. Conversely, if the hand

was located adjacent to the shoulder, the elbow would be fully bent. Finally, shoulder