Key Info Rollout

Select the biped. > Motion panel > Key Info rollout

Tools in the Key Info rollout allow you to do the following:

When the Vertical Center of Mass track is selected you can change the vertical dynamics of the motion, on a key-by-key basis. When the Horizontal Center of Mass track is selected you can change the balance factor for shifts in weight distribution.

Activating Parameters

Groups of the Key Info rollout are unavailable depending on what part of the biped is selected and if a key is current. Body Vertical, Body Horizontal and Body Turning refers to the three tracks used to animate the biped center of mass. Select one of the three center of mass tracks on the Track Selection rollout, then use Next Key or Previous Key to find a key to edit.

Tension Continuity and Bias (TCB)

Rather than creating extra keys to fine-tune the motion of the biped limbs, you can use the TCB controls to adjust ease in, ease out, and limb trajectory on keys that already exist.


To change TCB for a biped arm

  1. Turn on Trajectories.

  2. Select a biped arm.

  3. Use Next or Previous key to locate an arm key.

  4. Change the Tension, Continuity, and Bias spinners.

    The trajectory changes to reflect the new parameters. Play the animation.


Next Key-Previous Key: Find the next or previous keyframe for the selected biped part.

The field displays the key number.

Set Key: Use either Set Key or turn on the 3DS MAX Animate button to create keys when you are moving biped objects. Using the Set Key method, you can experiment with different biped poses without updating the motion until you find the desired pose. You can also quickly fine tune your motion by setting a key and adjusting the key parameters on the Key Info rollout without having to transform the biped in the viewports.

0 is a keyboard shortcut for setting keys.

Note: If a biped key is current, then TCB, XYZ position spinners, and IK Blend parameters can be updated without using Set Key or having the Animate button turned on.

Note: If 3DS MAX bones using the IK Controller or 3DS MAX Particle Emitters are linked to the biped, or if you are displaying 3DS MAX trajectories or ghosting, the Animate button must be on while the biped is positioned. These objects update their parameters in real time as they are positioned.

Delete Key: Deletes the key of the selected object at the current frame.

By default biped arm, hand, and finger keys are stored in the clavicle track. If you delete keys for any one of these objects, you lose positions for the rest of the arm objects at that frame. If you plan on extensive hand animation, turn on Arms in the Separate Tracks group of the Animation Properties rollout. This creates separate tracks for each biped arm object. Deleting an upper arm key will preserve hand and finger keys.

Set Parents: Turn on to create keys for the parent objects as well as the selected object only when Separate Tracks are turned on in the Animation Properties rollout.

Set Parents is used to store the position of the entire limb when a biped limb is moved using inverse kinematics, instead of rotated using forward kinematics. For example, if Set Parents is turned off and Separate Tracks are turned on in the Animation Properties rollout for the biped arms, then the arm will snap back to its original position if you transform the biped hand.

If Separate Tracks are turned on for a biped body part, then turn on Set Parents. This allows you to use the Move transform to position the biped limbs.

If a hand key is created, then forearm and upper arm keys are also created.

Trajectories: Shows and hides trajectories for the selected biped object. You can edit keys on the bipeds horizontal and vertical track by turning on Trajectories, turning on Sub-Object, selecting the horizontal or vertical center of mass track and transforming keys in the viewports.

Time: Enter a value to specify when in time the key occurs.

Use this to fine tune keyframe timing on a character by moving a key backwards and forwards in time.

XYZ Position: Reposition the selected biped part using these spinners.

A hand or foot can be repositioned in world coordinate XYZ. The biped center of mass can also be positioned using these spinners.

Ease To: Slows the velocity of the animation curve as it approaches the key. Default=0.

High Ease To causes the animation to decelerate as it approaches the key.

The default setting causes no extra deceleration.

Ease From: Slows the velocity of the animation curve as it leaves the key. Default=0.

High Ease From causes the animation to start slow and accelerate as it leaves the key.

The default setting causes no change of the animation curve.

TCB Graph: Charts the effect that changing the controller properties will have on the animation. The red mark at the top of the curve represents the key. The marks to the left and right of the curve represent an even division of time to either side of the key.

The TCB graph is a stylized representation of the animation around a single key.

Tension: Controls the amount of curvature in the animation curve.

High Tension produces a linear curve. It also has a slight Ease To and Ease From effect.

Low Tension produces a very wide, rounded, curve. It also has a slight negative Ease To and Ease From effect.

The default value of 25 produces an even amount of curvature through the key.

Continuity: Controls the tangential property of the curve at the key. The default setting is the only value that produces a smooth animation curve through the key. All other values produce a discontinuity in the animation curve causing an abrupt change in the animation. Default=25.

High Continuity values create curved overshoot on both sides of the key.

Low Continuity values create a linear animation curve. Low continuity creates a linear curve similar to high tension except without the Ease To and Ease From side effect.

The default setting creates a smooth continuous curve at the key.

Bias: Controls where the animation curve occurs with respect to the key. Default=25.

High Bias pushes the curve beyond the key. This produces a linear curve coming into the key and an exaggerated curve leaving the key.

Low Bias pulls the curve before the key. This produces an exaggerated curve coming into the key and a linear curve leaving the key.

The default setting distributes the curve evenly to both sides of the key.

Simple: Collapses the lower part of the Key Info rollout, for simplified viewing.

Biped Dynamics Parameters

These parameters apply to the biped center of mass and are used by character studio to calculate the biped's airborne trajectory based on gravity (GravAccel) and time between footsteps, the amount of knee bend on landing (Ballistic Tension) and how the biped objects adapt to maintain balance (Balance Factor).

Balance Factor: Position the biped's weight anywhere along a line that extends from the center of mass to the biped's head. This center of mass (Body Horizontal track) parameter can be keyframed. To activate Balance Factor select the Horizontal Track (in the Track Selection rollout), set a key and enter a value in the Balance Factor field.

A value of 0 in the first image causes the biped not to compensate for weight. A value of 2 in the second image causes the biped pelvis to move away from the Center of Mass to compensate for weight.

The Balance Factor determines how far the biped's hips will shift forward or backward to compensate for forward or backward bending of the spine. When the biped has a normal weight distribution between the upper and lower body, the default value of 1 causes the hips to swing backward as the biped bends over to compensate for the forward weight.

At times, when the biped leans, you will want the biped's hips to refrain from shifting to compensate for the forward weight. This would be when the biped is sitting or falling down. A Balance Factor of 0 (the minimum value) causes the hips to stay still when the biped leans forward or backward.

A value of 0 places the biped's weight at the center of mass. A value of 1 places the biped's weight above the center of mass. A value of 2 places the biped's weight in the head. Click the spinner up arrow to move the biped's weight distribution toward the head. Range=0.0 to 2.0; Default=1.

Note: You can also shift the center of mass by turning on Figure mode, selecting the center of mass object, and using Rubber Band mode to move the center of mass to a new position. This method cannot be keyframed, but it allows you to move the center of mass outside the biped body. To simulate pushing a heavy object, move the center of mass behind the biped for example.

Dynamics Blend: Select the Body Vertical track (center of mass vertical track) and control the amount of gravity in an airborne period, as in a running or jumping motion. This parameter has no effect on a walking motion where footsteps overlap.

The vertical center of mass track Dynamics Blend parameter is set to 1 for both keys (white squares) in the first jump, and to .5 in the second jump.

A value of 1 uses the GravAccel value to calculate gravity. A value of 0 removes the effects of gravity calculation and flattens a jumping or airborne motion.

Ballistic Tension: Select the Body Vertical track (COM) and control the amount of spring or tension when the biped lands or takes off from a jump or run step. The change is subtle.

A walk cycle will not activate this value. The biped has to be airborne, then the Lift and Touch vertical keys will display a Ballistic Tension value.

If there are more than three vertical keys during a support period, you can also edit Ballistic Tension for the lift-off key; otherwise Biped uses the same value for touchdown and lift-off, since it is assumed that there is only one vertical dip in the motion. Low values are high tension (less dip in the trajectory). Default=0.5; Range=0 to 1;