For our investigation we have restricted the world to a stage

= Initial assumptions: the setting for our investigation

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

For our investiga= tion we have restricted the public or physical world to a stage. Action in the world is represented= by the movement of an actor. The act= or is represented by his skeleton, his bones.&nb= sp; The stage supports the weight of the actor by counteracting the forc= e of gravity pushing down from the actor’s centre of gravity. From a physics perspective we have= two domains. Optics to describe w= hat 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 relev= ant 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).&= nbsp; Position on the stage is indicated by 3 dimensions: x=3Dwidth, y=3Dheight, and z=3Ddep= th. Stage centre, level with the stage= , is given by x=3D0, y=3D0, z=3D0. We call this the 3D Cartesian Stage geometry. This is our ‘= real world’ geometry.

	StageRear

StageRight=	Stage-right-rea= r	Stage-left-rear	StageLeft
Stage-right-fro= nt	Stage-left-front

	StageFront
	(director)

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 audien= ce perspectives that are relatively stable.&n= bsp; 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, relativ= e to the actor facing the audience across the front of the stage.) The fifth stable perspective is fr= om the top, from the rafters, called ‘StageTop’. The perspectives of other members = of the audience are known from their seating arrangements, and are assumed to be stable once they are seated.

The sixth perspec= tive of special interest is the actor’s actual current perception, based on h= is orientation and the viewpoint through his eyes. This perspective is important for guiding his motions, since the actor cannot and should not respond to somet= hing he cannot see. On the other h= and, if there is significant information that is allowed to be seen it should influence future action.