Expression Sets for AutoSolve

Before you can begin creating AutoSolve animation in Retargeter you'll need go through the quick and simple 'Character Setup' process.  This will be done once per character and typically takes between 10 and 30 minutes to complete.  The result of this process is the 'Character Setup File', an XML file used when opening a performance in Retargeter. In this article, we'll cover how to create an Expression Set, the second part of this process.  In order to create an Expression Set, you'll need to have completed the 'Control Setup' process, which is covered in the 'Character Setup Walkthrough' article.

What is an Expression Set?

The Expression Set is a group of pre-defined facial expressions that are used by Retargeter. It serves the purpose of letting the user define how each part of the face should look when the actor does certain movements. The subsequent AutoSolved animation is generated by combining the tracking data in the .fwr file with the expressions. Expression Sets are specific to a character and will need to be created once for each character.

*Note -  An Expression Set is required for using AutoSolve, though posed-based retargeting can still be used without an Expression Set. If a .fwr is loaded and there is no Expression Set in the character xml, the AutoSolve functions will be automatically disabled.

How to Create an Expression Set

Step 1: Add Controls in Character Setup

To create expressions, you must already have completed the process of adding controls in Character Setup. If you have not already done so, please start at the Character Setup Walkthrough before continuing.

Step 2: Creating Your Character's Expressions

To create Expressions, you'll actually be creating animation poses on your characters.  Be prepared to create some animation in your Maya/Max/etc. scene file.

1. Create or load a Scene File with your character that contains no animation.  Save a new file that will be your "expression set" scene file. (e.g. “MyCharacter_ExpressionSet.mb”, "MyCharacter_ExpressionSet.max", etc.)
2. In your Scene, set the animation timeline range to 0-50
3. Select all of your character's controls and set zeroed out (default) keyframes on each frame from 0 to 50. This will ensure that the animation generated by each expression will only include the controls relevant to the given expression.
4. Load the Retargeter plugin and open Character Setup
5. In the Character Setup dialog, go to the File menu and select "Load." Select your character xml for the rig.
6. Select the ‘Expression Set’ tab. If you see a message that reads, "Expression Set is disabled until you have added your rig controls in the 'Control Setup' tab.", it means you need to complete Control Setup before moving on.
7. Select a row in the list to view an expression. (Selecting a row will also take you to the frame that is listed in your scene.) The example image shows you what the Expression is and an example of how it should look. You can also mouse-over the row for a Tool-tip that describes the Expression.
8. For each Expression in the list:
   1. Select a given expression in the list
   2. Using the image as reference, pose your character rig to look like that expression. Be sure to only use the controls relevant to the given expression, every other control should be in its default position.
   3. Once you are satisfied with how your expression looks, click the "Finish Selected Expression(s)" button. This tells Retargeter that the expression is correct the way it is in the scene and to use that data.
      

*Note: Your expressions will not be fully saved into the character setup xml until you save your files in the step below.

Step 3: Save Your Files

1. Save your Character Setup file (File -> Save)
2. Save your Scene file for easy access when iterating, etc.

Editing an Expression Set

Editing an Expression Set is a common way to improve the quality of an AutoSolve. Expressions that have conflicting controls or are not set up properly can have an adverse effect on the results. If you’d like to edit an Expression Set to improve animation results in AutoSolve, follow the steps below:

1. Open your saved Scene File or Character Rig. Ideally, you've saved the scene you used to create the Expression Set, so your expressions will already exist in the scene for you to edit.
2. Load your saved Character Setup file. 
3. Optional - If you are using a clean version of your character rig with no expressions on it, use the ‘Apply Expressions to Character’ button on the Expression Set tab. This will load the currently saved Expressions onto your rig on the appropriate frames.
4. Update Expressions by navigating to the appropriate frame, editing your facial pose, and clicking “Finish Selected Expression(s)” 
5. Save your Scene File (Keep a copy of your scene for easy editing later)
6. Save your Character Setup xml file

Once you have an updated Expression Set saved in your Character Setup (XML) file, you can now re-open your shot in Retargeter and click 'Retarget' to see your changes.