3.1 Global reference system

The Global Reference System (Figure 2) is a fixed system associated with the scene. Its origin is located on the floor at the projection of the midpoint between the hips in the model's initial position. Its axes do not change orientation when the model is reoriented.

In the initial position, the ZG axis is vertical and positive upward; the XG axis is horizontal and positive toward the model's right; and the YG axis is perpendicular to the other two and positive toward the front of the model.