This operation can be used to create "motion wires" which can be used with the IK Move Along Wire operation if you want to "fine tune" the motion capture data.

Figure 3.15 Wires can be generated from any joint on a skeleton

The generated wire is created from the tip of the bone that is further from the root.

The Make Wire from Joint Motion operation should come after the Update Skeleton operation.

Table 3.10 Make Wire from Joint Motion parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being animated.
Bone	No	The bone whose tip is being used to create the wire.
Wire	No	The name of the wire. If you select None, you are prompted for a name when you animate the script. If you choose an existing wire, that wire is modified when the script is animated.
Visible?	No	Should the wire be visible as each segment is drawn?

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Quaternion Rotate Bone

Using a quaternion rotations avoids "gimbal lock" which can sometimes happen when a bone is closely aligned with the global X, Y, or Z axes. Some animators find it easier to use than other rotation commands, since you pose the skeleton and copy the current state of one or more bones into a cue (much like keyframing).

Figure 3.16 Left, original skeleton; right, copy, with upper left arm rotated with Quaternion Rotate Root

To use the Quaternion Rotate Bone operation:

1. Create a Quaternion Rotate Bone channel.

2. Insert a cue where you want the rotation to occur.

3. (CLICK-M) on a cue.

The following menu appears:

4. Rotate the target bone into the desired pose.

5. (CLICK-L) on CopyOrientation.

6. (CLICK-L) on the Animate button in the N-Dynamics script editor.

The script animates, and the bone rotates, hitting each cue in the channel.

Table 3.11 Quaternion Rotate Bone parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being animated.
Bone	No	The bone being rotated.
Orientation	Yes	The orientation of the bone at the given frame, described in quaternion notation.

Using a quaternion rotations avoids "gimbal lock" which can sometimes happen when a skeleton is closely aligned with the global X, Y, or Z axes.

Figure 3.18 Left, original skeleton, right, skeleton root rotated on the Y axis with Quaternion Rotate Root

To use the Quaternion Rotate Bone operation:

1. Create a Quaternion Rotate Bone channel.

2. Insert a cue where you want the rotation to occur.

3. (CLICK-M) on a cue.

The following menu appears:

4. Rotate the target bone into the desired pose.

5. (CLICK-L) on CopyOrientation.

6. (CLICK-L) on the Animate button in the N-Dynamics script editor.

The script animates, and the bone rotates, hitting each cue in the channel.

Table 3.12 Quaternion Rotate Root parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being animated.
Orientation	Yes	The orientation of the bone at the given frame, described in quaternion notation.

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Read Acclaim Data

• A skeleton, typically read in as an Acclaim format skeleton. The skeleton can also be built from scratch as long as it is named appropriately to match the specified .asf and .amc files.
• A .asf file that describes that skeleton (e.g., bone names, bone length, degrees of freedom, and so forth)
• A .amc motion capture file (which describes the motion for that skeleton).

To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the selected skeleton, use an Update Skeleton operation.

The Read Acclaim Data operation should come before the Update Skeleton operation.

Table 3.13 Read Acclaim Data parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being animated.
Skeleton Dir.	No	The directory containing the skeleton file.
.asf File Name	No	The skeleton file.
Motion Dir.	No	The directory containing the motion capture data file.
.amc File Name	No	The motion capture data file.

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Read Biovision Data

• A skeleton, typically read in as a Biovision format skeleton. The skeleton can also be built from scratch as long as it is named appropriately to match the specified .bvh file.
• The .bvh file itself. The .bvh file includes both a description of the skeleton (e.g., the skeleton's bone names, bone length, degrees of freedom, and so forth) and any motion capture data (which describes the motion for that skeleton).

To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the skeleton, use an Update Skeleton operation.

The Read Biovision Data operation should come before the Update Skeleton operation.

Table 3.14 Read Biovision Data parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton on which this operation is performed.
Motion Dir.	No	The directory containing the motion capture data.
.bvh File Name	No	The name of the motion capture data file.

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Read Motion Analysis Data

• A skeleton, typically read in as a Motion Analysis format skeleton. The skeleton can also be built from scratch as long as it is named appropriately to match the specified .htr file.
• The .htr file itself. The .htr file includes both a description of the skeleton (e.g., the skeleton's bone names, bone length, degrees of freedom, and so forth) and any motion capture data (which describes the motion for that skeleton).

To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the skeleton, use an Update Skeleton operation.

The Read Motion Analysis Data operation should come before the Update Skeleton operation.

Table 3.15 Read Motion Analysis Data parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton on which this operation is performed.
Motion Dir.	No	The directory containing the motion capture data file.
.htr File Name	No	The name of the motion capture file.

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Rotate Root

Figure 3.20 Using rotate root on a skeleton

As with any dynamic operation, you can specify any number of cues in any channel. You might, for instance, want the skeleton to change its X, Y, and Z rotation at frame about a third of the way into the script, then change its X rotation twice more near the end of the script:

Figure 3.21 Enter cues in the appropriate channel wherever you want the skeleton to rotate

After inserting the cues where you want the rotations to occur, you can edit the cue values:

1. (CLICK-M) on the cue.

2. Adjust the value using the slider.

3. (CLICK-L) on the Animate button.

The following parameters can be set for the Rotate Root operation:

Table 3.16 Rotate Root parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being animated.
X Angle	Yes	The value by which the root should be rotated around its X axis.
Y Angle	Yes	The value by which the root should be rotated around its Y axis.
Z Angle	Yes	The value by which the root should be rotated around its Z axis.

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Scale Bone

Figure 3.22 Scaling a bone

Note. You must make sure that the bone being scaled does not have a fixed length. If the DOF defined for this bone does not allow it to be scaled, the operation executes, but the bone doesn't change length.

To check the DOF for the referenced bone, (SHIFT-L) on the bone in the N-Geometry window and try to resize it using the Scale Bone operation. If the bone has a fixed length, the following dialog box appears:

Figure 3.23 Scaled bones cannot have fixed length

You can (CLICK-L) on Yes to free the bone.

To check the fixed length setting for multiple bones at the same time, (SHIFT-L) on the skeleton and (CLICK-L) on DOF Editor, then make sure the Scale DOF is checked for that bone:

Figure 3.24 Use the DOF editor to set the "scalability" of multiple bones at once; Min and Max values are displayed if the Scale DOF is active

In Figure 3.24, the second bone can be scaled; all others are of fixed length.

Table 3.17 Scale Bone parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton on which this operation is performed.
Bone	No	The bone being scaled.
Mode	No	Determines how the dynamic value in Factor is applied to the Bone. Set uses the value in Factor for the new bone length. Add adds the value in Factor to the current bone length. Multiply uses the value in Factor as a factor by which to multiply the bone length.
Factor	Yes	The dynamic value used to scale the bone.

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Transform Root

Figure 3.25 Transforming the Root node

This operation could be used to move the entire skeleton in 3D space, to rotate the skeleton around its root, or scale the entire skeleton object larger or smaller. Note that by default the scale subchannel is not dynamic, although it can be made so. Dynamic channels are created for XYZ rotations and offsets:

Figure 3.26 In a Transform Root operation, rotate and translation channels are automatically dynamic

The following parameters can be set with the Transform Root operation:

Table 3.18 Transform Root parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being transformed.
X, Y, and Z Offset	Yes	The dynamic values for the X, Y, and Z move of the skeleton (using the root).
X, Y, and Z Angle	Yes	The dynamic values for the X, Y, and Z angles of rotation for the skeleton.
Scale	Can be	The value (which can be dynamic) for the scale of the skeleton.

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Translate Root

Figure 3.27 Translating the Root, in this case, along the Z axis

This operation has fewer parameters than the Transform Root operation described earlier; translations do not include scaling or rotation of the target object.

Table 3.19 Transform Root parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being translated.
X, Y, and Z Offset	Yes	The dynamic values for the X, Y, and Z move of the skeleton (using the root).
Scale	Can be	The value (which can be dynamic) for the scale of the skeleton.

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Update Skeleton

The Update Skeleton operation is visually divided into several logical sections:

• Skeleton lets you select the skeleton to update and toggle its visibility.
• Skins controls how any skins assigned to the skeleton are updated.
• Root Transformations controls whether any transformation, rotation, or scaling operation are applied to the skeleton as directed by any previous motion capture that has been read or through any Transform Root operations.

  Table 3.20 Update Skeleton parameters

  Element	Variable	Dynamic?	Description
  Skeleton
  	Name	No	The skeleton to be updated.
  	Visible?	No	Should the skeleton be made visible after it is updated?
  Skins
  	Update?	No	Should the skin(s) assigned to this skeleton be updated as the skeleton is animated?
  	Displace?	No	Should skin displacements driven by bone rotation be applied as the skeleton is animated?
  Root Transformations
  	Translate?	No	Should root transformations be applied to the skeleton?
  	Rotate?	No	Should root rotations be applied to the skeleton?
  	Scale?	No	Should root scaling operations be applied to the skeleton?
  Motion Editing
  	Limit DOFs?	No	Should the skeleton's DOFs be used when animating?
  	Save Pose?	No	If you are using Difference Posing, described in the Skeletal Animation System Tutorial, set this to Yes.

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Update Skins

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Write Acclaim Data

This operation might be used, for example, after you had used the IK Move along Wire operation to tweak a previously saved motion capture (.amc) file. These saved files can then be reread using the Read Acclaim Data operation.

Table 3.22 Write Acclaim Data parameters

Parameter	Dynamic?	Description
Skeleton	No	The skeleton being used to generate the Acclaim data.
Skeleton Dir.	No	The .asf file with which the .amc file should be associated.
.asf File Name	No	The name of the .asf file.
Motion Dir.	No	The directory into which the motion capture file should be written.
.amc File Name	No	The name of the motion capture file.

Note. If you write out a frame range of the script, written frames are numbered 1 through N, regardless of their frame number in the script.

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X Rotate Bone

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XYZ Rotate Bone

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Y Rotate Bone

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Z Rotate Bone

Copyright © 1996, Nichimen Graphics Corporation. All rights reserved.