Overview over my approach to the visual perception of poses on a stage

I extend the 3D framework approach to include the perception of major skeletal components such as hips, shoulders, head, legs, and arms.

• Note that we need to perceive the limbs in order to infer the actions of the perceived animal (or actor). I illustrate the use of such perception with 3 scenarios: a predacor chasing a prey, a fitness follower mimicking the actions of the leader, and an animal exploring a cage to find food.

Unlike the action controls that focus on the muscle control of joint rotations, I focus on the more easily visible rotation of the limbs. I use the 'invible cage', the 3D framework, to help define two parameters: level and direction.

• Level describes the extent to which the limb is parallel to the floor of the 3D cage (the stage).
• How level a limb is can be seen from the side or the front. If it is level as measured by a level (a companion to the plumb line), then it has a level of 0 degrees. If it points straight up or straight down then it is 90 (or 270) degrees from level.
• Direction describes the angle between the orientation of the limb and the front-to-back line through the cage.
• The direction of a limb can best be seen by looking straight down. If a limb stretches straight forward then it has a 0 degree angle of direction. If it points straight sideways then it has a 90 (or 270) degree angle of direction.

The third angle measures the 'twist' of the limb relative to the more central body part it is attached to. 0 degrees is no twist at all.