Introduction Case Study: Jack Nichoolas 5 What's A character sheet? Deconstructing the body Creating the Pelvis The Spine The Shoulders The Elbows The Knee As Tools Evolve, Concepts Remain Valid

Figure 12: The knee.

The knee took me some time to understand (Figure 13). The key to realistic movement from this joint lies in keeping the mass of the knee fairly constant as the leg bends. The bones of the lower leg, the fibula and tibia, actually slide around the lower end of the femur (Figure 13C). To achieve this movement, place the knee's axis of rotation a little above the vertical meeting point of the two bones (above the end of the femur), not where the two bone ends meet. As seen from the side and front, the axis should be centered horizontally within the knee's mass. By placing the knee joint away from the surface of the geometry, we get a bulging effect, which (unlike the shoulders) we want in this case.

The rest of the skeleton is positioned by aligning the remaining bones to the character sheet as well. Note that bone joints in one part of the body behave similarly in other locations. For instance, the joints of the finger and toe bones work just like the knee: lower bones orbit about a point partway up the higher bone. The meeting of the ankle and the foot is similar to the elbow: there is a protrusion by the heel that is akin to the point of the ulna. Finally, as noted before, the bones of the neck meet the head towards the rear of the skull, just as the rest of the spine relates to the rib cage.