Motion Capture Conversion Parameters Dialog

Create or select a biped. > Motion panel > Motion Capture rollout > Load Motion Capture File button > Open a file.
Load motion capture data. > Motion panel > Motion Capture rollout > Convert from Buffer button

Motion capture and marker data typically have keys at every frame. Filtering motion capture data reduces keys, making the job of altering or personalizing the motion data much simpler. Other filtering options include footstep extraction, applying the skeletal structure stored in the motion capture file to the biped, looping the data, importing a portion of the motion capture file and selecting tracks to load.

Motion Capture Buffer

Any file imported using Load Motion Capture File is stored in its raw (pre-filtered) form in the motion capture buffer. This buffer is used to try new filtering options with the Convert from Buffer command, and to paste keys from the raw motion capture data to the biped using Paste from Buffer on the Motion Capture rollout. The Show Buffer command displays a stick figure that represents the buffered data.

Create your own library of imported and optimized motion capture data by saving .bip files for use with other characters or as part of a longer script in Motion Flow mode. Use a biped that has no mesh attached with Physique. You import the data, adjust it to your liking, and save it as a .bip file. You can also run standard .bip files through this filtering process to create loops or to extract footsteps from a freeform animation.

Note: Marker files contain position data. Regular motion capture files contain joint rotation data.

Biped.ini Parameters

The Biped.ini text file in the plugcfg directory has parameters for smoothing the values of motion capture joint angles for the Body's center of mass, the spine and head during import. The lines appear as below:






Higher values of smoothing will cause the Biped importer to filter and "smooth out" the data using a Gausian filter, taking out spikes and jerks in the motion. These values must be integers and may go from 0 to any high number, but practical values would probably always be less than 10. For most cases, smoothing is not needed, so the default values for Biped 3.0 are set to zero.


To use Fit to Existing to import a motion capture file

Use a motion capture file that contains footsteps and other motion. A handspring motion would be ideal for this example.

  1. Select a biped.

  2. Click Motion panel > Motion Capture rollout > Load Motion Capture File.

  3. Select a motion capture file.

    The Motion Capture Conversion Parameters dialog displays.

  4. Set Footstep Extraction to On, then click OK.

    The motion capture file loads.

  5. Select Motion Capture rollout > Show Buffer to display raw motion capture data as a red stick figure, then select Play.

    During the "hand spring" period of the playback, the hands on the red stick figure representing the raw motion data touch the ground. The biped, using the filtered data, is positioned higher and cannot reach the ground.

    Dynamics calculates the biped higher than the raw motion data because the footsteps before and after the handspring are so far apart in time. Creating a freeform period in Track View and reloading the same file using the Fit to Existing option will match the biped position to the motion capture position during the handspring.

  6. Find the Footsteps track for the biped in Track View.

  7. Right-click in the footsteps area of the Track View Edit window, then select Edit Free Form (No Physics) in the Footstep Mode dialog.

  8. Click the "handspring" area between the footsteps. It turns to a solid yellow.

    Motion capture data will replace the data in this freeform period.

  9. Reload the same motion capture file using the Fit to Existing option in the Motion Capture Conversion Parameters dialog.

    The freeform area created in Track View is replaced with motion capture data. The biped closely matches the red stick figure during the handspring part of the playback.


Motion Capture File: Displays the file to be imported.

Footstep Extraction: Motion capture data can be applied to the biped in one of three ways:

Conversion: Chooses the type of key processing.

Up Vector: Sets the vertical axis used in the motion capture data.

Scale Factor: Multiplies the stored talent size by this value and size the biped accordingly.

Footstep Extraction group

Options here are active when Footstep Extraction is on.

Extraction Tolerance: Sets the sensitivity of footstep extraction. Biped determines if the footstep is there by checking that the foot does not move beyond the distance determined by the Extraction Tolerance value. Smaller numbers are more sensitive and extract more footsteps. The value is a percentage of foot length.

The default value is 0.15. Increase this value to .2 or .25 if too many footsteps are generated.

Sliding Distance: Creates a sliding footstep when positional tolerance is reached. This value is a percentage of foot length. By default the foot must slide its own distance (100), before a sliding footstep is created.

Use this with motion capture files that contain sliding feet. A sliding footstep can be created manually by setting IK Blend > 0 for a biped foot at a "touch" state key (biped foot first touches a footstep).

Note: Sliding footsteps display as a footstep with a line through the center.

Sliding Angle: Creates a sliding footstep when rotational tolerance is reached. This value is in degrees. The default is set high (360 degrees), the foot must make a complete turn before a sliding footstep is created.

Use this with motion capture files that contain feet that pivot, as in a dance motion.

Note: Sliding footsteps display as a footstep with a line through the center.

Only Extract Footsteps Within Tolerance: Turns on Z axis Tolerance. These controls filter out footsteps that do not fall within a given range of the ground plane. Use this when filtering motions, such as hopping or pitching a baseball, in which a foot may come off the ground and remain stationary, but its position is not intended as a footstep.

Tolerance: Value is a percentage of leg length.

From Z Level: Set a Z value (ground).

Flatten Footsteps to Z=0: Moves extracted footsteps to Z=0. Use this to flatten out minor differences in the height of the extracted footsteps.

Start: Start importing at this frame. Default is frame 0, the first frame.

End: Stop importing at this frame. Default is the last frame of the clip.

Loop: Loop the data by the value set here.

This is relative. Succeeding loops start where the previous loop left off. The clips are not blended and may require editing unless the original clip was designed to loop.

Use this for clips designed to loop.

Note: This often works best if Footstep Extraction is tuned off.

Limb Orientation

The biped elbow and knee hinge joints are perpendicular to the triangles formed by the shoulder-elbow-wrist and hip-knee-ankle respectively. Resolve errors in the motion capture data that break this rule by using either the angle or point method.

Angle: Moves the knee or Elbow position to create the biped joint key.

Point: Rotates the shoulder-elbow-wrist or hip-knee-ankle to create the biped joint key.

Auto: Auto reads exact hand and foot positions from the motion capture data, Character Studio then places the knees and elbows in a natural position. For marker files involving running and walking, this option can clean up the data nearly instantly, regardless of how many markers were used and where they were placed.

Key Reduction Settings group

Key reduction keeps the original motion intact and intelligently filters out more than 80% of the keys in the motion capture file, making the process of altering the biped animation much simpler.

Use the Tolerance and Minimum Key Spacing settings to fine-tune key reduction for a specific track (body part). Specify whether or not to filter a track in the Filter column.

These settings are available only Conversion is set to Use Key Reduction.

Tolerance: Sets the maximum angular or positional deviation for a track.

Values are in units of translation for position tracks, and in degrees for rotation tracks.

Minimum Key Spacing: Set the minimum number of frames between keys.

Tolerance is computed first, then Minimum Key Spacing computes further key reduction.

A Minimum Key Spacing value of 10 for the head track ensures that no two keys are closer than 10 frames for this track.

Set All: Forces all tracks to the values set in these fields.

Higher values here can determine how much key reduction is possible while preserving the original motion.

Filter: Turn off to prevent filtering of the motion capture data into a track. When this is off, there is no key reduction for the track.

Talent Definition group

Loads a Figure Structure File (.fig) and a Pose Adjustment file (.cal) prior to importing a marker file. Typically you correct a marker file by importing it and adjusting the biped scale and limb positions relative to the markers, then saving .fig and a .cal file using Save Talent Figure Stucture and Save Talent Pose Adjustment on the Motion Capture rollout. These files can then be loaded in the Talent Definition area when importing marker files created by the same actor in a motion capture session.

Figure Structure: Load a .fig file.

Pose Adjustment: Load a .cal file.

Browse: Browse for a .fig and .cal file.

Use: Use either or both the .fig and .cal files to adjust marker files during a marker file import procedure.

Load Parameters: Loads a motion capture parameter file (.moc).

Save Parameters: Saves a motion capture parameter file (.moc).