We combined physically based modeling and parameterization to generate realistic speech animation on synthetic faces. We used physically based modeling for muscles. Muscles are modeled as forces deforming the mesh of polygons. A parameterization technique is used for generating mouth shapes for speech animation. Each meaningful part of a text, which is a letter in our case, corresponds to a specific mouth shape and the mouth shape is generated by setting a set of parameters used for representing the muscles and jaw rotation. We also developed a mechanism to generate and synchronize facial expressions while speaking. Some tags specifying the facial expressions are inserted into the input text together with the degree of the expression. In this way, the facial expression with the specified degree is generated and synchronized with speech animation.

Continuous deformable models are generally represented using a grid of control points. The elastic properties are then modeled using the interactions between these points. The formulations based on elasticity theory express these interactions using stiffness matrices. These matrices store the elastic properties of the models and they should be evolved in time according to changing elastic properties of the models. However, forming the stiffness matrices at any step of an animation is very difficult and sometimes the differential equations that should be solved to produce animation become ill-conditioned. Instead of modeling the elasticities using stiffness matrices, the interactions between model points could be expressed in terms of external spring forces. In this paper, a spring force formulation for animating elastically deformable models is presented. In this formulation, elastic properties of the materials are represented as external spring forces as opposed to forming complicated stiffness matrices. (C) 1997 Elsevier Science Ltd.

Physically-based modeling remedies the problem of producing realistic animation by including forces, masses, strain energies, and other physical quantities. The behavior of physically-based models is governed by the laws of rigid and nonrigid dynamics expressed through a set of equations of motion. This paper discusses various formulations for animating deformable models. The formulations based on elasticity theory express the interactions between discrete deformable model points using the stiffness matrices. These matrices store the elastic properties of the models and they should be evolved in time according to changing elastic properties of the models. An alternative to these formulations seems to be external force formulations of different types. In these types of formulations, elastic properties of the materials are represented as external spring or other tensile forces as opposed to forming complicated stiffness matrices.>

A methodology and the implementation are described of a graphical waveform editor which is used to create functional test programs on an engineering workstation. The system has been implemented such that timing and test patterns can be created or customized for different target testers utilizing diverse timing technologies. The graphical waveform editor is described in the context of an integrated test-program generation environment. The features of the editor include timing and pattern editing, subroutine definition, time set selection, logic state definition and translation, synchronization, event definition and search, pattern differences and other similar functions. A summary of user experience and planned enhancements is presented.>

Cataloged from PDF version of article.