Transition Editor

Transitions

A good transition links two clips together seamlessly; the motion through the transition should appear natural, as though the motion was captured as one long motion sequence. Like an AB roll transition in video editing, an appropriate section in both clips is selected for the transition (dissolve) from the source clip to the destination clip. Velocity differences between the source and destination clips are matched during the period of transition producing a seamless result. By default, Minimum Motion Loss is used to find likely start frames in the source and destination clips when clips are appended to a script. Optimized transitions can be computed by using Optimize Transition in the upper right-hand corner of the Transition Editor dialog. Optimized transitions use a minimum foot sliding method to compute transitions. Optimized transitions take longer to compute, but produces very smooth motions.

Although only one arrow is used to represent a transition between two clips in the Motion Flow Graph, any number of transitions can be named and stored in the Transition Editor representing that transition. If, for example, you create 5 different transitions between two clips for one script, all of these transitions are available in a new script that uses the same two clips. Think of Motion Flow Graph as a data storage area; if all of the scripts are deleted, the transitions are preserved and can be stored in an MFE file.

Automatic Transitions

When you create a script, default transitions are used between the clips. Default transitions use minimum motion loss and are quick to compute. However, the best quality transitions are the optimized transitions. Once the Transition Editor is open, the first thing to try, before manual editing, are the optimized transitions (upper-right corner of the dialog).

Length (Transition Duration)

Set the duration of a transition in the Length field. A value of 10, for example, creates a transition of 10 frames between the source and destination clips. During the period of transition, the velocity of the source clip is interpolated to the velocity of the destination clip. If the transition takes place at the last frame of the source clip and the first frame of the destination clip, and Length is set to 10, then the last frame of the source clip is interpolated with the first 10 frames of the destination clip.

Editing Transitions Manually (Ghosts)

Manually setting the Start Frame for the source and destination clips offers the most control. Unwanted motion in either clip can be avoided and judging the best Start Frames for both clips is left to you.

The Ghost area Frame spinners allow you to view and scrub the source and destination clips by displaying stick figures (ghosts); yellow and red stick figures represent the source and destination clips. When a suitable Start Frame is located for both clips, use Set Start Frame in the Ghost area to copy the Frame values to the Start Frame fields in the Source and Destination Clip areas.

Scrubbing the time slider over the transition period enables you to view the biped's transition from the yellow stick figure (source) to the red stick figure (destination).

Other Transition Editor Features

Rolling and Fixed specify whether a clip is rolling (in motion) or fixed (single frame) during the transition. Change the direction of the destination clip using the Angle field.

Other parameters in the Transition Editor allow you to create and name new transitions, scroll through the saved transitions, jump to the transition-starting frame, set automatic transition parameters, and go to the next transition in the script

You can save all transitions and their attributes in an MFE file.

See Customizing Transitions to manually and automatically customize transitions.

Interface

Length

Sets the number of frames for the duration of the transition.

Transitions are calculated by matching velocities in both clips. Smooth out abrupt velocity changes using longer transitions.

Ease In

Ease-in value for the source clip.

Ease Out

Ease-out value for the destination clip.

Transition Focus

Lets you specify a focus point on the biped where the transition takes place. The Mixer will attempt to match movement based on this selection. For example, if Left Foot is selected, the transition will use the left foot as a focal point during the transition, aligning the motion of the left foot in both clips as much as possible during the transition. Default=Auto.

AutoThe transition focus is calculated by averaging the overall position of the biped as it transitions from one clip to the next.
Center Of MassThe transition focus is based on the center of mass position of the biped as it transitions from one clip to the next.
Left FootThe transition focus is based on the left foot position of the biped as it transitions from one clip to the next.
Right FootThe transition focus is based on the right foot position of the biped as it transitions from one clip to the next.
Both FeetThe transition focus is based on an averaged foot position of both of the biped's feet as it transitions from one clip to the next.

NoteThe best way to see the differences between the transition foci is by watching the yellow and red ghosts.

Angle

Sets the direction of the destination clip.

The angle of the destination clip is automatically set for best body fit between the two clips when the Start Frame values change. Use Angle to change the direction of the destination clip.

Probability

Set a probability value for random transitions. This is used by Create Random Motion when a random script is generated.

Previous/Next Transition buttons, Start Frame controls, and Optimize button

Previous Transition: Go to the previous transition in the transition track.

Displays the previous transition in the Transition Editor, moves the time slider to the start frame of the previous transition and highlights the previous clip in the transition track.
Next Transition: Go to the next transition in the transition track.

Displays the next transition in the Transition Editor, moves the time slider to the start frame of the next transition and highlights the next clip in the Scripts list.
Start Frame: This text field displays the number of the first frame of the transition.
Go To Start Frame: Moves the time slider to the first frame of the transition.
Optimize Transition: Displays the Transition Optimization dialog.

Options in the Transition Optimization dialog allow you to search for the range over which the optimizer searches for the transition.

Source Clip and Destination Cip groups

Clip range

This text field displays the range of the source or destination clip. The ranges are relative to the clip itself, not to the frame range of the full animation.

Start Frame

Sets the transition start frame for the source or destination clip. The start frame is relative to the clip itself, not to the frame range of the full animation.

Transition options

These choices control how the transition is interpolated.

RollingRetains the clip motion during the transition.
FixedFor the source clip, this option freezes the biped at the Start Frame position during the transition. For the destination clip, this option freezes the biped at the End Frame position. If Fixed is chosen for both the source and destination clips, the transition is a gradual interpolation from one frozen pose to another.

Ghost subgroups (Source and Destination clips)

The Ghost group Frame spinners allow you to view and scrub the source and destination clips by displaying stick figures (ghosts); yellow and red stick figures represent the source and destination clips. The source and destination bipeds might not be near each other during this scrubbing process; the destination clip will be repositioned when you click Set Start Frame is clicked. When you locate a suitable start frame, click Set Start Frame to copy the values in the Frame field to the Start Frame field. Monitor foot position status in the field provided.

Set Start Frame: Copy the value in the Frame field of the Ghost area to the Start Frame field in the Clip area. The position of the destination clip changes to match the biped body in the destination clip to the biped body in the source clip.

Locate an appropriate start frame for the source and destination clips by using the Frame spinner and viewing the positions of both stick figures, then click Set Start Frame.

The destination clip is rotated and positioned to match both bipeds. Use the Angle spinner to reorient the destination clip.
Frame: Use the Frame spinner to scrub a stick figure back and forth, which allows you to determine a start frame for the source and destination clips. Visual feedback of the stick figures is a good way to judge which start frames are needed for the source and destination clips.

Playback group

These controls let you play back the transition from the Transition Editor dialog.

Play Transition

Click to play the transition. Click again to stop playback.

Speed

Chooses the playback speed.

1/4 x Plays at one-quarter of real time.
1/2 x Plays at half real time.
1 x (The default.) Plays at real time (full speed).

Frames Before/Frames After

Set the number of frames to play before and after the transition period.

Selected Only

When on, plays back only the selected biped. Default=off.

Play Ghosts

When on, shows transition ghosts during playback. Default=off.

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Create Transition: Click to create a new transition. The transition number field increments. Any number of transitions can be stored.

NoteClicking OK saves the displayed transition. Create Transition is used only if you want to work on a new transition.
Delete Transition: Click to delete a transition.
Previous Transition: Go to the previous stored transition. This button is grayed if no previous transition exists.
Next Transition: Go to the next stored transition. This button is grayed if no next transition exists.
Active transition: Displays the number of the transition that is currently active.
Name field: In this field, you can enter a name or a comment for the current transition. On the Motion Flow rollout, the text you enter here appears to the right of the original clip name.
OK: Store transitions and exit the dialog.