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880 Chapter 14: character studio
Accelerating Gr avity
The GravAccel parameter on the Dynamics &
Adaptation rollout (page 2–980) alters the degree
of gravitational pull imposed on the biped during
its a irborne periods between active footsteps.
The GravAccel default value is based on the
standard calculation for the Earth’s gravity and
its effects on a man of average height. When the
GravAccel parameter is increased, the effects of
gravity are decreased, and the biped jumps hig her.
The GravAccel parameter can be set separately for
each biped in the scene.
GravAccel values increase height of jump.
(Left=500, Middle=1000,Right=1500).
You can change GravAccel at any t ime during the
animation process to affect the biped’s vertical
airborne motion, both for keys already created and
for animation not yet created. This value cannot
be animated; t he current GravAccel value is used
throughout the biped’s footstep sequence.
Changes to the GravAccel parameter have no
effect whatsoever on the amount of time the biped
spends in the air.
Tip: If you want to change GravAccel back to its
default value but don’t remember what that was,
you can find out by creating another biped of the
same height and noting its GravAccel value.
Note: If there is not enough gravitational
acceleration or time in the air to account for
differences in vertical heig ht (such as a biped
falling from footsteps on a ledge in slow motion),
the biped is placed on the ground at the touchdown
frame, causing a discontinuity. You can fix this
by either increasing GravAccel or increasing the
amount of t ime be tween footsteps in Track View.
See Editing Footstep Timing (page 2–869).
Touch a nd Li f t D y na mics
When footsteps are activated for a footstep pattern
that includes airborne periods, Body Vertical keys
are set at each Touch and Lift key frame.
Basedonthetimeintheairandthebiped’sheight,
character studio ca lculates the height to which the
biped will jump. From this, the software figures
outhowhardthebiped’slegswouldhavetopushat
the Lift frame to reach this height, and how much
the legs would have to bend to absorb the force of
the landing at the Touch frame. B ody Vertical keys
are set at the Lift and Touch frames accordingly.
You can adjust the timing of touch and lift
dynamics by:
• Changing B ody Vertical keys at the Touch and
Lift frames.
• Setting, changing or deleting Body Vertical
keys during a footstep.
• Changing t he stiffness or springiness of the
biped’slegsatTouchandLiftframeswiththe
Ballistic Tension parameter.
B allistic Tension
Ballistic tension refers to the stiffness or springiness
of the biped’s landing at the end of a jump,
or takeoff at the start of a jump. The Ballistic
Tension parameter (page 2–954) changes the
biped’smotiononlywhenitissetforfootsteps