Animating expressive faces across languages

This paper describes a morphing-based audio driven facial animation system. Based on an incoming audio stream, a face image is animated with full lip synchronization and synthesized expressions. A novel scheme to implement a language independent system for audio-driven facial animation given a speech recognition system for just one language, in our case, English, is presented. The method presented here can also be used for text to audio-visual speech synthesis. Visemes in new expressions are synthesized to be able to generate animations with different facial expressions. An animation sequence using optical flow between visemes is constructed, given an incoming audio stream and still pictures of a face representing different visemes. The presented techniques give improved lip synchronization and naturalness to the animated video.     

Reusable specification templates for defining dynamic semantics of DSLs

Software and Systems Modeling - In the context of model-driven engineering, the dynamic (execution) semantics of domain-specific languages (DSLs) is usually not specified explicitly and stays...     

Toward automatic extraction of expressive elements from motion pictures: tempo

The paper addresses the challenge of bridging the semantic gap that exists between the simplicity of features that can be currently computed in automated content indexing systems and the richness of semantics in user queries posed for media search and retrieval. It proposes a unique computational approach to extraction of expressive elements of motion pictures for deriving high-level semantics of stories portrayed, thus enabling rich video annotation and interpretation. This approach, motivated and directed by the existing cinematic conventions known as film grammar, as a first step toward demonstrating its effectiveness, uses the attributes of motion and shot length to define and compute a novel measure of tempo of a movie. Tempo flow plots are defined and derived for a number of full-length movies and edge analysis is performed leading to the extraction of dramatic story sections and events signaled by their unique tempo. The results confirm tempo as a useful high-level semantic construct in its own right and a promising component of others such as rhythm, tone or mood of a film. In addition to the development of this computable tempo measure, a study is conducted as to the usefulness of biasing it toward either of its constituents, namely motion or shot length. Finally, a refinement is made to the shot length normalizing mechanism, driven by the peculiar characteristics of shot length distribution exhibited by movies. Results of these additional studies, and possible applications and limitations are discussed.     

计算语义学视角下的文本风格研究

文本风格研究是计算语义学研究的领域之一。利用计算语义学的微观结构量化赋值和主题域义场分析的方法加深对不同文本语义核心的理解,推出了测算不同文本语义核心的关联值公式,以数值对比形式为不同文本的相似语义核心的测定提供了量化标准,使借助计算语义学手段进行文本风格研究成为可能。     

An expressive three-mode principal components model of human action style

We present a three-mode expressive-feature model for representing and recognizing performance styles of human actions. A set of style variations for an action are initially arranged into a three-mode data representation (body pose, time, style) and factored into its three-mode principal components to reduce the data dimensionality. We next embed tunable weights on trajectories within the sub-space model to enable different context-based style estimations. We outline physical and perceptual parameterization methods for choosing style labels for the training data, from which we automatically learn the necessary expressive weights using a gradient descent procedure. Experiments are presented examining several motion-capture walking variations corresponding to carrying load, gender, and pace. Results demonstrate a greater flexibility of the expressive three-mode model, over standard squared-error style estimation, to adapt to different style matching criteria.     

Automatic expressive deformations for implying and stylizing motion

Three-dimensional computer animation often struggles to compete with the flexibility and expressiveness commonly found in traditional animation, particularly when rendered non-photorealistically. We present an animation tool that takes skeleton-driven 3D computer animations and generates expressive deformations to the character geometry. The technique is based upon the cartooning and animation concepts of “lines of action” and “lines of motion” and automatically infuses computer animations with some of the expressiveness displayed by traditional animation. Motion and pose-based expressive deformations are generated from the motion data and the character geometry is warped along each limb’s individual line of motion. The effect of this subtle, yet significant, warping is twofold: geometric inter-frame consistency is increased which helps create visually smoother animated sequences, and the warped geometry provides a novel solution to the problem of implied motion in non-photorealistic imagery. Object-space and image-space versions of the algorithm have been implemented and are presented.     

In Scott-Strachey style denotational semantics,parallelism implies nondeterminism

A minimum algebraic structure needed in Scott-Strachey style denotational semantics for parallel programs is developed. Some elementary algebra shows that nondeterministic semantics is inherently and uniquely present. Conversely, any simple nondeterministic semantics provides uniquely a semantics for a minimal parallel computation capability.Research supported in part by National Science Foundation grants MCS77-08486 and MCS80-03433.     

RFuzzy: Syntax, semantics and implementation details of a simple and expressive fuzzy tool over Prolog

We present the RFuzzy framework, a Prolog-based tool for representing and reasoning with fuzzy information. The advantages of our framework in comparison to previous tools along this line of research are its easy, user-friendly syntax, and its expressivity through the availability of default values and types.In this approach we describe the formal syntax, the operational semantics and the declarative semantics of RFuzzy (based on a lattice). A least model semantics, a least fixpoint semantics and an operational semantics are introduced and their equivalence is proven. We provide a real implementation that is free and available. (It can be downloaded from http://babel.ls.fi.upm.es/software/rfuzzy/.) Besides implementation details, we also discuss some actual applications using RFuzzy.     

Modal Locomotion: Animating Virtual Characters with Natural Vibrations

We present a general method to intuitively create a wide range of locomotion controllers for 3D legged characters. The key of our approach is the assumption that efficient locomotion can exploit the natural vibration modes of the body, where these modes are related to morphological parameters such as the shape, size, mass, and joint stiffness. The vibration modes are computed for a mechanical model of any 3D character with rigid bones, elastic joints, and additional constraints as desired. A small number of vibration modes can be selected with respect to their relevance to locomotion patterns and combined into a compact controller driven by very few parameters. We show that these controllers can be used in dynamic simulations of simple creatures, and for kinematic animations of more complex creatures of a variety of shapes and sizes.     

Animating Quadrupeds: Methods and Applications

Films like Shrek, Madagascar, The Chronicles of Narnia and Charlotte's web all have something in common: realistic quadruped animations. While the animation of animals has been popular for a long time, the technical challenges associated with creating highly realistic, computer generated creatures have been receiving increasing attention recently. The entertainment, education and medical industries have increased the demand for simulation of realistic animals in the computer graphics area. In order to achieve this, several challenges need to be overcome: gathering and processing data that embodies the natural motion of an animal – which is made more difficult by the fact that most animals cannot be easily motion-captured; building accurate kinematic models for animals, with adapted animation skeletons in particular; and developing either kinematic or physically-based animation methods, either by embedding some a priori knowledge about the way that quadrupeds locomote and/or adopting examples of real motion. In this paper, we present an overview of the common techniques used to date for realistic quadruped animation. This includes an outline of the various ways that realistic quadruped motion can be achieved, through video-based acquisition, physics based models, inverse kinematics or some combination of the above.     

Animating human locomotion with inverse dynamics

Because the major force components (the internal muscular forces and torques) are not known a priori over time, you cannot use forward dynamics to predict how the human body will walk. The alternative to the apparently intractable problem of specifying the joint torque patterns in advance is to use inverse dynamics to analyze the torques and forces required for the given motion. Such an analysis can show, for example, that the motion induces excessive torque, that the system is out of balance at a certain point, or that the step length is too great. We present a method of using an inverse dynamics computation to dynamically balance the resulting walking motion and to maintain the joint torques within a moderate range imposed by human strength limits. This method corrects or predicts a motion as indicated by the inverse dynamics analysis. Dynamic correctness is a sufficient condition for realistic motion of nonliving objects. In animating a self-actuated system, however, visual realism is another important, separate criterion for determining the success of a technique. Dynamic correctness is not a sufficient condition for this visual realism. An animation of dynamically balanced walking that is also comfortable in the sense of avoiding strength violations can still look quite different from normal human walking. A visually realistic and dynamically sound animation of human locomotion is obtained using an effective combination of kinematic and dynamic techniques     

Animating strings with twisting,tearing and flicking effects

String‐like objects in our daily lives, for example shoelaces, threads, rubber cords, plastic fiber and spaghetti, have a wide variety of materials. Such string‐like objects also exhibit interesting behaviors such as twisting, tearing (by stretching or twisting), and bouncing back when pulled and released. In this paper, we present a method that enables these behaviors and simulates such materials in traditional string simulation methods that explicitly represent a string by particles and segments. Specifically, we offer the following three contributions. First, we introduce a method for handling twisting effects with both uniform and non‐uniform torsional rigidities. Second, we propose a method for estimating the tension acting on inextensible strings in order to reproduce tearing and flicking (bouncing back), whereas the tension for an extensible object can be computed via stretched length. The length of an inextensible object is maintained constant in general, and thus, we need a novel approach. Third, we introduce an optimized grid‐based collision detection for accelerating the computation. We demonstrate that our method can produce visually plausible animations of string‐like objects with various material properties, and it is a fast framework for interactive applications such as games. Copyright © 2012 John Wiley & Sons, Ltd.     

Linking denotational semantics with operational semantics for web services

Web Services have become more and more important in these years, and BPEL4WS (BPEL) is a de facto standard for the web service composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. The denotational semantics and operational semantics have been explored for BPEL. The two semantic models should be consistent. This paper considers the linking of these two semantics. Our approach is to derive the denotational semantics from operational semantics for BPEL, which aims for the consistency of the two models. Moreover, the derivation can be applied in exploring the program equivalence easily, especially for parallel programs.     

Meaningful modeling: what's the semantics of "semantics"?

The Unified Modeling Language (UML) is a complex collection of mostly diagrammatic notations for software modeling, and its standardization has prompted an animated discussion about UML's semantics and how to represent it. We have thus set out to clarify some of the notions involved in defining modeling languages, with an eye toward the particular difficulties arising in defining UML. We are primarily interested in distinguishing a language's notation, or syntax, from its meaning, or semantics, as well as recognizing the differences between variants of syntax and semantics in their nature, purpose, style, and use.     

Rendez-vous with metric semantics

A comparative semantic study is made of an element of the family of concurrent object-oriented programming languages. Particular attention is paid to two notions: (i) dynamically evolving process structures, including a mechanism to name and refer to processes and a means to create new processes, and (ii) rendez-vous between processes involving the sending and answering of messages and the induced execution of method calls. The methodology of metric semantics is applied in the design of operational and denotational semantics, as well as in the proof of their equivalence. Both semantics employ domains which are determined as fixed points of a contracting functor in the category of complete metric spaces. Moreover, fruitful use is made of the technique of defining semantic meaning functions as fixed points of contracting higher-order mappings. Finally. syntactic and semantic continuations play a pervasive role.     

Animating the Language Machine: Computers and Performance

A range of inter-disciplinarydiscourses consider the computer-mediatedwriting space as a unique performance mediumwith characteristic protocols. Drawing oncontemporary performance theory, literarycriticism, and communication theory, the authorproposes that technologists, academics, andartists are developing idiomatic rhetorics – alingua franca – to explore the technicaland expressive properties of the new ``languagemachines' and their hypertextual environments.The role of improvisation – and itscross-disciplinary protocols – provides afurther focus in the discussion of computingpractice and performance.     

Animating Formal Specifications with Inheritance in a DL-Based Framework

Dynamic logic (DL) provides a suitable formal framework to model actions and reasoning about them. <$>\cal OASIS<$> is a language for the specification of object-oriented conceptual models. In our model, specialisation is a relation between classes that defines an inheritance mechanism through static and dynamic partitions. A variant of DL (including the deontic operators for permission, prohibition and obligation) is the formalism used in <$>\cal OASIS<$> to deal with changes of state, triggers, preconditions, protocols and operations. The animation of conceptual models in order to validate the specification is an interesting topic. We have worked on translating <$>\cal OASIS<$> specifications automatically to concurrent environments in order to obtain a prototype useful to validate specifications by animation. The aim of this paper is to show that it is feasible to translate static and dynamic partitions automatically into dynamic logic formulae. Thus, using the same developed schema of animation it is possible to execute <$>\cal OASIS<$> specifications including inheritance.