Alfred

Alfred – a System for Intuitive Facial Expression Control

The application

Alfred is a Facial Animation System designed to create facial expressions for Animated Agents in an easier, more intuitive and faster way than conventional animation tools. The project uses a gamepad and a data glove for user input. The user input can be interpreted with three different methods.

Alfred uses the Facial Action Coding System (FACS) by Paul Ekman and Wallace Friesen for the description and creation of the facial expressions. The tool is a standalone application based on the Horde 3D graphics engine. While used to control one specific virtual character at the moment, it can be easily reconfigured to control any FACS-based character’s face.

Alfred has won the “GALA Jury Award for 2008” at IVA 2008.

Alfred was part of the International Conference on Intelligent User Interfaces 2009.

For detailed information about Alfred please refer to:
N. Bee, B. Falk, E. Andre, Simplified facial animation control utilizing novel input devices: a comparative study, International Conference on Intelligent User Interfaces 2009

Media

Screenshots & Photos

head expressions xpad glove gui_pad mesh

Videos

Video for IVA GALA (352*288 px – 13,5 MB)
High Res. Video for IVA GALA (704*576 px – 20,9 MB)

Novelty

Although facial expressions have become more and more important in animated characters, most facial animation tool are using conventional GUIs for the animation setup. Especially morphtarget-based systems like Poser or Valve’s Faceposer rely heavily on the use of sliders.

Alfred tries to overcome the limitations and complexity of these animation tools by using hardware controllers (gamepad or dataglove). The user can choose between different modes of inputs: direct control of the action units, modifying of basic emotions or blending basic expression. These hardware controllers have the advantage that they allow the editing and mixing of multiple animation parameters at the same time. Furthermore they provide haptic control of these parameters, allowing the user to focus on the character’s expression and not on the animation system.

Technical Information on Alfred’s Head

The character head has been modelled in Luxology modo and Autodesk 3D Studio Max using subdivision surfaces and sculpting techniques. The textures are either digital handpainted (color & specular map) or baked from a high-resolution mesh (normal map).

The head has a polycount of abot 21.000 triangles. The textures have a size up to 2048*2048 pixels. Please take a look a the media section for more details of the mesh topology.

Animations & expressions of the head are realized through Morph Targets which represent the individual Action Units of FACS.

Architecture

Alfred’s architecture is based on two independent modules: The first module processes the user input and interprets it into action units. The following controls & interpretation models are available:

  • Direct control of the action through a conventional slider-based GUI
  • Direct control of three different face regions through the analog-sticks of an gamepad
  • Choosing a basic facial expression and modifying it by an adapted and reduced set of action units
    (analog-sticks of gamepad)
  • Blending two or more basic facial expressions (analog-sticks of gamepad)
  • Direct control of six different facial regions through the finger bend of a dataglove. The glove’s spatial
    position is used to select the facial regions.

This module also contains a constraint system for the facial expressions which allows only anatomical possible expressions.

The second module translates the action units into facial expressions and renders the graphic output. Both modules communicate via UDP socket.

The created facial expressions can be saved and loaded in a XML format. The configuration of the controllers, the basic expressions and their reduced controller sets are based on data from on the “Facial Expression Repertoire” Database.

Performance

The software runs smoothly on one single PC with a modern graphics card. Most capacity is used by the
rendering module. The controller module itself requires very little capacity.

A user evaluation of 17 persons has shown that Alred’s gamepad-based interface is significantly faster and more fun to use than traditional slider-based interface. The quality and the level of control remain the same. The system received a positive feedback from professional CG artists at Chimera Entertainment. Especially the animation control through gamepad and the blending of basic emotional expressions were received well.

References

  • P. Ekman and W. Friesen. Facial Action Coding System: A Technique for the Measurement of Facial
    Movement. Consulting Psychologists Press, Palo Alto, 1978
  • D. Thalmann, Using Virtual Reality Techniques in the Animation Process, Virtual Reality Systems
    (Earnshaw R., Gigante M., Jones H. eds.), Academic Press, pp. 143-159, 1993
  • “Facial Expression Repertoire” Database, research.animationsinstitut.de