Select the biped. > Motion panel > General rollout > turn on Figure mode > Structure rollout
Turn Figure mode on to enable parameters on the Structure rollout. The Structure rollout provides parameters for changing the biped's skeletal structure to match your character mesh (dinosaur, robot, human and so on) and a name field to rename the biped center of mass object and append this name to all the links in the biped hierarchy.
After setting parameters to suit your character, use the Height parameter to scale the biped to the size of the mesh representing your character. This is the first step in fitting a biped to a mesh in Figure mode.
To scale a biped and a Physique mesh
Select the biped, turn on Figure mode, and then change the biped height on the Structure rollout.
The biped and mesh scale together.
To name the biped
This actually names the biped center of mass and appends the name to all the links in the biped hierarchy.
Select a biped in the viewports.
On the Motion panel, on the Structure rollout, type a name in the Root Name field.
Identifying the links of the character in any name dialog is simplified.
Root Name: Displays the name of the selected biped's center of mass object. The center of mass (COM) is the root of the biped hierarchy; it is visible as a diamond shaped object in the pelvis area. The Root Name is appended to all the links of the biped hierarchy.
To simplify selecting biped links in the Select by Name dialog on the 3DS MAX toolbar, change the default center of mass name "Bip01" to the name your character will use. If you change the Root Name from Bip01 to John, for example, all of the links will have the name "John" appended to them, for example "John Pelvis" and "John L thigh. "
Arms: Specifies whether or not arms will be generated for the current biped.
Neck Links: Specifies the number of links in the biped neck. Range=1 to 5.
Spine Links: Specifies the number of links in the biped spine. Range=1 to 5.
Leg Links: Specifies the number of links in the biped legs. Range=3 to 4.
Tail Links: Specifies the number of links in the biped tail. A value of 0 specifies no tail. Range=0 to 5.
Ponytail1/2 Links: Specifies the number of Ponytail Links. Range=0 to 5.
Animates hair with ponytail links. Ponytails are linked to a character's head and can be used to animate other appendages. Reposition ponytails in Figure mode and use them to animate a character's jaw, ears, nose, or anything that should move with the head.
Unlike the process of selecting the biped hand and dragging to reposition the entire arm, ponytails must be keyed using rotational transformations.
Fingers: Specifies the number of biped fingers. Range=0 to 5.
Finger Links: Sets the number of links per finger. Range=1 to 3.
Toes: Specifies the number of biped toes. Range=1 to 5.
Toe Links: Specifies the number of links per toe. Range=1 to 3.
Characters wearing shoes may only need one toe with one link.
Ankle Attach=0.25 and Ankle Attach=0.5
Ankle Attach: Specifies the right and left ankles' point of attachment along the corresponding foot block. The ankles may be placed anywhere along the center line of the foot block from the heel to the toe.
A value of 0 places the ankle attachment point at the heel. A value of 1 places the ankle attachment point at the toes. Click the spinner up arrow to move the ankle attach point toward the toes. Range=0 to 1.
Height: Sets the height of the current biped.
Use to size the biped to your mesh character before Physique is attached. This parameter is also used in a procedure to scale your character after Physique is attached.
Triangle Pelvis: Turn on to create links from the upper legs to the lowest biped spine object when Physique is attached. Normally the legs are linked to the biped pelvis object.
The pelvis area can be a problem when the mesh is deformed with Physique. Triangle Pelvis creates a more natural spline for mesh deformation.
Triangle Pelvis creates links
Triangle Pelvis creates two links that extend from the legs to the lowest biped spine object. A link from the biped pelvis to the lowest spine object is also created. This provides natural deformation to this area after Physique is applied and the character is moving. If you are working on a new character, turn this on before applying Physique. If Bones is turned on in the Display rollout, links from the legs to the lower spine object are visible.