Display Pole-Vector shows IK orientation and where the pole-vector controller will be.
The IK orientation is determined by the plane of the three joints in the IK chain.
Turn on Fit Mode so the red visualizers update live as joints are moved. You can also select the knee joint and press Insert to move only that joint while immediately seeing the pole-vector direction update.
Display Pole-Vector visualizes IK orientation and pole-vector controller direction.
