2.1.1 The stage: the main setting for our investigation

The stage where the action takes place, and the audience to view the action

For our investigation we have restricted the public or physical world to a stage. Action in the world is represented by the movement of an actor. The actor is represented by his skeleton, his bones. The stage supports the weight of the actor by counteracting the force of gravity pushing down from the actor�s centre of gravity. From a physics perspective we have two domains. Optics to describe what the audience can see, and what the actor can see. The second domain deals with the movement of the bones, which is normally done by muscles applying forces to rotate the bones about joints. The information about how much force to apply is supplied by neurons. We shall simplify by focusing only on the information that must be supplied by these nerve cells to get the relevant muscles to incrementally move the appropriate bones.

Stage dimensions are 10m width by 10m deep by 6m high. Audience seating is all around, with special observers in StageFront, StageRight, StageLeft, and StageRear. The stage is flat level (no rake). Position on the stage is indicated by 3 dimensions: x=width, y=height, and z=depth. Stage centre, level with the stage, is given by x=0, y=0, z=0. We call this the 3D Cartesian Stage geometry. This is our �real world� geometry.

We have at least five stable perspectives. We shall use the �StageFront�, the director�s perspective as the �normal� perspective for the audience. �StageRight�, �StageRear�, and �StageLeft� give three more audience perspectives that are relatively stable. Stage directions typically use a perspective similar to that of the �StageRear� audience perspective. This perspective defines the stage terms for stage directions. (Traditionally it is based on the actor�s perspective, relative to the actor facing the audience across the front of the stage.) The fifth stable perspective is from the top, from the rafters where the lights are located, called �StageTop�.

The perspectives of members of the audience depend on their seating arrangements.

The actor�s perspective is based on the orientation of his body and head, and thus the perception through his eyes. This perspective allows the audience to know that some action is hidden from the actor even through clearly visible to the audience.