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886 Chapter 14: character studio
Freef or m A nimat ion
Freeform animation of a biped swimming
While char acter studio calculates vertical
dynamics and gravity based on its footstep-driven
technology, you don’t always want your character
str ic tly under these cont rols. You might want
the character to fly, swim, or to do something
improbable in a ph ysical world. For these
situations, Biped supports a comprehensive set of
freeform animation controls that allow you to take
total creative control over your character’s pose,
movement, and timing.
character studio gives you the option to animate
characters using freeform mode exclusively, or
to create freeform periods during a footstep
animation. In f reeform mode (without footsteps),
you can pose every joint of your character exactly
as you like using traditional keyframe methods.
Handsandfeetcanbelockeddowninspaceby
setting planted keys. You can also animate the
pivot points for hands and feet to simulate rolling
motion. You can blend dynamically between
forward kinematics and inverse kinematics to
introduce hig her-level control.
To use freeform animation in Footstep mode,
you create freeform periods between footsteps
using Track View – Dope Sheet. You can conver t
an existing footstep animation into a freeform
animat ion and back again. This lets you mix the
use of footstep and freeform methods.
Wa rn in g : You can’t add a freeform period at the
beginning or end of a footstep animation.
Tip:
Ifyouwanttodothis,stretchoutthetiming
for the first or last set of footsteps, then convert the
footstep animation to freeform.
Fr e efo rm M e t h o d
A freeform animation contains no footsteps;
instead it relies on the transforms of the biped
body objects and center of mass. Use Freeform for
motions lik e swimming or falling where footsteps
are not necessary. If you are a familiar with
creating al l of your keyframes manually to animate
a character, you may want to use the freeform
method exclusively.
To star t a freeform animation, tur n on Auto Key
and start positioning the biped. You c an also leave
Auto Key off and use the red set key buttons on the
Key Info rollout (page 2–954) to create keyframes.
You can also create f reeform animation by
importing motion capture data and choosing
freeform rather than footstep.
Tip: Take advantage of both methods by combining
footsteps and freeform animation. You can create
a freeform period for any airborne period between
footsteps. A freeform period replaces the ballistic
motion calculated using the GravAccel value with
auserdefinedsplinemotion.
If you are us ing footstep extraction with mot ion
capture data, you often n eed a freeform interval to
accommodate falling or tumbling motion in the
data. TheFittoExistingoptionontheMotion
Capture Conversion Parameters dialog allows
for a combination of both methods. Extracting
footsteps from motion capture files eliminates
sliding feet, a common problem with motion
capture data.
Notethatwhileyoucanaddafreeformperiodto
a footstep animation, you cannot add a footstep
period into a freeform animation. If you want to