ShapeJitter

The Effects->ShapeJitter command in the Motion module allows you to apply random motions to the control points of a model. You can specify the magnitude of the individual x, y, and z components, as well as the motion frequency to determine how "jittery" the resulting motion is.

To apply random motion to control points of objects in a hierarchy, use the Effects->HrcShapeJitter command in the Motion module.

ShapeJitter is typically used to:

• Create random high frequency motion, such as bees buzzing about a hive, or small particles suspended in a liquid.
• Add the appearance of flexibility to parts of a character that are not deformed by the animator and look too "stiff." These parts can be shape jittered to look more flexible.

Procedure

1. Create a model.
2. Choose the Effects->ShapeJitter command.
   
   The ShapeJitter dialogue box is displayed.
   
   
3. Set the parameters as desired.
4. Pick the object.

The ShapeJitter icon appears indicating that the effect is active.

Note:

The location and shape of the icon do not affect the result.

As with other Motion effects, the parameters may be further edited or animated by selecting the icon and choosing Effects->Edit Parameters in the Motion module.

Parameters

Seed

Specifies a seed value for the random number generator. Use different values to create different random patterns of motion.

Frequency

Sets the relative frequency of the effect. A value of 1 sets a very high frequency, while smaller values reduce the frequency to create a smoother effect.

Amount

Specifies the relative magnitudes for the shape jittering in x, y, and z.

Tension

Sets the tension for the curve interpolation used in the calculations.

Frame Start and End

Sets the start and end frames for the effect.

Frame Rate

For the motion timing to be correct, this option must be set to the same frame rate being used in SOFTIMAGE 3D, usually 30.0 or 24.0 frames per second.

Cumulative

Sets the offsets to accumulate over time. This parameter is important when used in conjunction with the Group Vertices option.

Group Vertices

Allows you to group a specified number of vertices together. When set, each group of vertices move by the same amount. This is useful, for example, if the model was created by applying the Duplicator effect to an entire polygon mesh object with a given number of vertices. By specifying that number of vertices as the parameter value, each member of the duplicate retains its shape when it is moved.

Number of Independent Streams

Random numbers are reused during the application of the effect to save memory. In certain cases, this can create discernible patterns in the random motion. To counteract this, simply increase the value of this parameter. As a general rule, the value should be equal to or greater than the cube root of the number of control vertices of the object. For example, if the object has 1,000 control vertices, the number of the independent streams should be 10 or more.

Next, Previous, Delete, Key, and Frame

Next advances to the next keyframe, Previous goes back to the previous keyframe, Delete removes a keyframe, and Key sets a keyframe at the frame you specify in the Frame text box. These controls are available only after you have set the initial parameters in the dialogue box and clicked Ok. To return to the dialogue box and edit keyframes for the effect, select the effect icon and choose the Effects->Edit Parameters command in the Motion module.

Last updated 02-apr-1998