Motion Mapping: Retargeting Biped Motion

One of the more powerful features of Biped is the ability to retarget or map the motion of any biped onto any other biped.

If you map the motion of a biped without a tail onto a biped with a tail, default tail motion for the biped with a tail will be computed. Default motion will also be computed when mapping the motion of a biped with fewer links in the legs, spine, or neck onto a biped with more links in the legs, spine, or neck. There are a few ways to perform motion mapping. You can:

• Go into Figure mode and change the structure of your biped. When you exit Figure mode, the new structure of the biped will adapt to the existing animation.
• Save a BIP or STP file from one biped, and load it onto another biped of a different structure and size.
• Copy footsteps from one biped, and paste them onto the footsteps of a differently structured and scaled biped.

Scale Stride Mode

Scale Stride mode gives you control over whether or not certain aspects of motion mapping occur.

If Scale Stride mode is active (the default):

• When you exit Figure mode after loading a FIG file or changing the biped's leg length, pelvis width, or height, the locations of the footsteps will be scaled to match the leg length and pelvis width, and gravity will be changed to match the new height of the biped.
• When you load a BIP or STP file, the locations of the footsteps in the file will be scaled to match the leg length and pelvis width of the existing biped. Gravity will be adjusted to be proportional to the gravity stored in the file. (A motion stored in a BIP or STP file has a gravity value associated with it.)
• When you paste footsteps copied from one biped onto another biped, the locations of the footsteps in the buffer will be scaled to match the leg length and pelvis width of the existing biped. Gravity will be adjusted to be proportional to the gravity stored in the file. (A motion stored in a BIP or STP file has a gravity value associated with it.)

If Scale Stride mode is not active, no computations will be performed in any of the above cases. Then you might see your biped moving over footsteps that are spaced inappropriately far apart or close together for the size of your biped. Typically, you should leave Scale Stride mode active, unless you want to maintain the spatial relationship between the biped and other objects in your scene.

Procedures

To turn off Scale Stride mode:

1. Select the biped, and go to the Motion panel.
2. On the Biped rollout, click the bar at the bottom to expand the rollout.
   

   (If the rollout is already expanded, the bar shows a minus sign at the left, instead of a plus.)

3. In the Modes group, click (Scale Stride Mode) to turn it off.

   The button changes to indicate stride scaling has been turned off.

   
4. Use (Figure Mode) to edit the figure.

   When you return to Keyframe mode or Footstep mode, the biped's stride length is unchanged, regardless of the biped figure's new proportions.