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facial animation


titleThe goal of realistic human facial representation has remained elusive for several reasons. First, the mechanisms that underline the face appearance and motion are extremely complicated. The appearance of the face is determined by how light bounces between multiple layers of skin, resulting in subsurface scattering. Furthermore, the face is deformed by the combined actions of ten different muscle groups. Moreover, a lot of the difficulties in creating realistic digital faces come from our well-honed ability to observe and interpret the faces and expressions of people around us. This ability makes us very proficient at noticing the slightest deviation from reality when observing digital images of the human face.

Traditional attempts at creating realistic faces have either involved a great deal of effort by talented artists or detailed mathematical simulations. The artistic approach is inherently limited by the amount of effort it takes to recreate, by hand, the realistic three-dimensional appearance of the human face. Although generations of talented artists have created very believable portraits and sculptures of human faces, creating a realistic facial model that reflects light and moves in a believable way remains a challenging task. The mathematical approach has its limitations too. Although, there are realistic mathematical models of the surface of the skin and of the face muscles, these simulations are unable to render the idiosynchrasies that are part of the identity of a person. The mathematical simulations provide generic motions and surfaces, but do not provide mechanisms by which to model variations across individuals.

These approaches have yet to produce results that could trick us into thinking we are looking at a real person's face and not a computer-generated image.

We are working on a new approach to put this "holy grail" of computer animation within reach: recording the appearance and motion of a real person to create a digital replica. While a photograph or a video capture of the appearance of a subject may be realistic, it does not give the freedom to change the view point or the light falling on the person's face. This would be expected for a digital actor existing in a synthetic environment. We have begun to address this issue by recovering the three-dimensional surface of a person's face from a set of images , its motion during a performance, and its appearance under different lights.

Our goal is to develop technologies that would permit the capture of a performer and to digitally reanimate him/her in an arbitrary scenario.

Following this data-driven philosophy we have built two systems: one that animates the face according to a recorded speech input and another that animates gaze according to an input video.


Visual Speech

title This system takes as input a recorded enunciation and translate it into a facial animation. The result is a believable facial animation that corresponds to the recorded audio. Our main contribution is to not only lip-synch the animation to the speech but also to render appropriately the expressive contents of the speech signal. To achieve this goal we process the input speech to extract both phonemic (lip-synching) and prosodic (expressivenes) features.

Here are a few examples of synthesized animations:

Example1 (4.8M), Example2 (3.6M), Example3 (2.7M)
Example4 (1M), Example5 (1.5M), Example6 (1.7M),

title We also present a new method for editing speech related facial motions. Our method uses an unsupervised learning technique, Independent Component Analysis (ICA), to extract a set of meaningful parameters without any annotation of the data. With ICA, we are able to solve a blind source separation problem and describe the original data as a linear combination of two sources. One source captures content (speech) and the other captures style (emotion). By manipulating the independent components we can edit the motions in intuitive ways.

We have deployed this animation system within a leadership training tool to embody the face of a synthetic mentor.

This work is done in collaboration with Yong Cao and Petros Faloutsos.

Here are a few examples of synthesized animations:


Gaze Animation

title

The purpose of this system is to generate gaze animation for a synthetic head. We used a neurobiological model developed by Laurent Itti to model human visual attention. We applied this model to a video representing the scene viewed by the synthetic character and extracted a sequence of feature points that represents the focus of attention of the character. Using this information along with a model of eye and head motion we can animate the gaze of a synthetic character.

This work is done in collaboration with Laurent Itti and Nitin Dhavale.

These videos illustrates the estimation of the focus of attention:

Article Article

Here are a few examples of synthesized gaze animation:

Article Article Article
These animations are best viewed with the DIVX codec installed.
Blend Shape Animation

We adopted previous works in blendshape animation and proposed an automatic, physically-motivated segmentation that learns the controls and parameters directly from the detailed input expressions. In addition, we provided rendering techniques which improve the visual realism of our blend shape model. Our system can be used in both motion-capture and keyframe animations.

This work is done in collaboration with Pushkar Joshi, Mathieu Desbrun, and Wen Tien.

Here is an example of using BlendShape models for motion-capture animation:

Article
Large Version (6.4 MB)
Small Version (5.1 MB)

Here are some example of using BlendShape models for keyframe animation at various region granularities:

Article Article Article
Large Version (3.0 MB)
Small Version (1.6 MB)
Large Version (4.0 MB)
Small Version (2.1 MB)
Large Version (4.0 MB)
Small Version (2.1 MB)

These animations are best viewed with the DIVX codec installed.


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