Abstract: This paper describes a system for creating a photo-realistic model of the human head that can be animated and lip-synched from phonetic transcripts of text. Combined with a state-of-the-art text-to-speech synthesizer (TTS), it generates video animations of talking heads that closely resemble real people. To obtain a naturally looking head, we choose a "data-driven" approach. We record a talking person and apply image recognition to extract automatically bitmaps of facial parts. These bitmaps are normalized and parameterized before being entered into a database. For synthesis, the TTS provides the audio track, as well as the phonetic transcript from which trajectories in the space of parameterized bitmaps are computed for all facial parts. Sampling these trajectories and retrieving the corresponding bitmaps from the database produces animated facial parts. These facial parts are then projected and blended onto an image of the whole head using its pose information. This talking head model can produce new never recorded speech of the person who was originally recorded. Talking-head animations of this type are useful as a front-end for agents and avatars in multimedia applications such as virtual operators, virtual announcers, help desks, educational, and expert systems.

Abstract: Visualization has become a critical component of simulation technology. Today we can't imagine doing a simulation without some kind of visualization to help communicate results and get better understanding of a model's behavior. Model build time and debugging have been significantly improved using 2D and 3D animation. The elements of visualization are discussed to help simulation practitioners understand where animation should be employed and how it can improve the process of simulation modeling. The future of visualization in simulation will also be discussed.

Abstract: Modeling and animation of cloth has experienced important developments in recent years. As a consequence, complex textile models can be used to realistically drape objects or human characters in a fairly efficient way. However, real-time realistic simulation remains a major challenge, even if applications are numerous, from rapid prototyping to e-commerce. In this paper, we present a stable, real-time algorithm for animating cloth-like materials. Using a hybrid explicit/implicit algorithm, we perform fast and stable time integration of a physically-based model with rapid collision detection and response, as well as wind or liquid drag effects to enhance realism. We demonstrate our approach through a series of examples in VR environments, proving that real-time animation of cloth, even on low-end computers, is now achievable.

Abstract: Students who received instruction including static chalkboard drawings and overhead transparencies to explain the behavior of gas particles in a can-crushing demonstration were given a demonstration-based quiz in which they were asked to predict what would happen when a similar can filled with water vapor was removed from the heat and sealed. They were also asked to explain their prediction in terms of the behavior of gas molecules. This paper reports some of the misconceptions that were identified from these students' explanations. As a result of these misconceptions, a computer animation depicting the chemical processes occurring in the can-crushing demonstration was created. Another set of students were instructed on the behavior of gas particles including the can-crushing demonstration and the computer animation and were given the same demonstration quiz. The responses from the two sets of students were then compared. The students who viewed the animation as part of their instruction on the particulate nature of gases were less likely to use explanations that relied solely on the application of mathematical relationships. These students were also more likely to report the importance of the condensation of water vapor and the pressure differential inside and outside the can in the can-crushing process.

Abstract: Performing a really interactive and physically-based simulation of complex soft objects is still an open problem in computer animation/simulation. Given the application domain of virtual surgery training, a complete model should be quite realistic, interactive and should enable the user to modify the topology of the objects. Recent papers propose the adoption of multiresolution techniques to optimize time performance by representing at high resolution only the object parts considered more important or critical. The speed up obtainable at simulation time are counterbalanced by the need of a preprocessing phase strongly dependent on the topology of the object, with the drawback that performing dynamic topology modification becomes a prohibitive issue. In this paper we present an approach that couples multiresolution and topological modifications, based on the adoption of a particle systems approach to the physical simulation. Our approach is based on a tetrahedral decomposition of the space, chosen both for its suitability to support a particle system and for the ready availability of many techniques recently proposed for the simplification and multiresolution management of 3D simplicial decompositions. The multiresolution simulation system is designed to ensure the required speedup and to support dynamic changes of the topology, e.g. due to cuts or lacerations of the represented tissue.

Abstract: We present a voxel-based collision detection method for clothed human animation. We speed up the performance of the voxel-based method by choosing an appropriate voxel size and using a fast voxelization approach. Based on the voxel method, we propose a self-collision detection method and a simplified collision detection method. First, the efficiency of self-collision detection is improved by taking advantage of the curvature and multi-layer methods. Second, the efficiency of cloth/human collision detection is improved by introducing auxiliary line segments. Some heuristics are provided to further increase the efficiency of collision detection. Experimental results demonstrate that our method is efficient for clothed human animation.

Abstract: The present invention is a system and method to provide customizable animation A motion capture database houses a library of human motion that is accessible via a client-server connection Users are allowed to select motion sequences and alter these motions in real time over a networked connection to create new and original works of art In one embodiment, blender software is used to interpolate and extrapolate from existing library data to create the new and original motion sequences, that are developed to comply with bio-mechanical laws, physics and human anatomy In another embodiment, users can bypass the bio-mechanical laws, physics and human anatomy and create mutations of the motion capture data The present invention not only allows real time animation manipulation, but it is accomplished over a network by using a client application and accessing the motion capture library and blending algorithm The created animation is created is purchased over the Internet, allowing a cost-effective means to create and purchase animations

Abstract: Visualization algorithms have seen substantial improvements in the past several years. However, very few algorithms have been developed for directly studying data in dimensions higher than three. Most algorithms require a sampling in three-dimensions before applying any visualization algorithms. This sampling typically ignores vital features that may be present when examined in oblique cross-sections, and places an undo burden on system resources when animation through additional dimensions is desired. For time-varying data of large data sets, smooth animation is desired at interactive rates. We provide a fast Marching Cubes like algorithm for hypercubes of any dimension. To support this, we have developed a new algorithm to automatically generate the isosurface and triangulation tables for any dimension. This allows the efficient calculation of 4D isosurfaces, which can be interactively sliced to provide smooth animation or slicing through oblique hyperplanes. The former allows for smooth animation in a very compressed format. The latter provide better tools to study time-evolving features as they move downstream. We also provide examples in using this technique to show interval volumes or the sensitivity of a particular isovalue threshold.

Abstract: Graphical animation is a way of visualizing the behavior of design models This visualization is of use in validating a design model against informally specified requirements and in interpreting the meaning and significance of analysis results in relation to the problem domain In this paper we describe how behavior models specified by Labeled Transition Systems (LTS) can drive graphical animations The semantic framework for the approach is based on Timed Automata Animations are described by an XML document that is used to generate a set of JavaBeans The elaborated JavaBeans perform the animation actions as directed by the LTS model

Abstract: The main purpose of this study was to explore different instructional attributes provided by animation in facilitating descriptive and procedural learning. In the study, subjects were eighth-grade and ninth-grade students. Spatial ability was used as a variable to observe students' learning of different knowledge. Both quantitative and qualitative methods were employed in exploring how students learned physics concepts. Animation has been used in instruction in scientific and mathematical learning for many years. However, recent advances in technology have permitted the creation of desktop animations for a wide range of instruction (Szabo & Poohkay, 1996). With the advent of Internet technology in recent years, various computer-based learning courses employing animation techniques have been developed to assist learning. The use of modern technologies has become common in education and is considered necessary for computer-based materials. For example, various mathematical problem-solving courses developed on the World Wide Web highlight the impact of visualization on learning (Dixon & Falba, 1997; Halpin & Kossegi, 1996). Many medical simulations using state-of-the-art technology are also available on the web to provide real-time animation for medical learning (Grange, Bunker & Cooper, 1997; Lehmann, Lehmann & Freedman, 1997). In designing interactive multimedia applications, animation is seen as an integral component in presenting information on the computer screen. The use of animation provides potential visual interest for presenting computer-based materials, which makes scientific learning more appealing and enjoyable to learners. Defined as a series of graphics that change over time and/or space, animation has been found effective in illustrating the complex structural, functional, and procedural relationships among objects and events (Park & Gittelman, 1992). Through the use of a model for interpretation, students can form accurate schematic representations while learning abstract concepts. The most effective arrangement of animated visual aids may vary with the differing spatial abilities of students. Literature suggests that students scoring high in spatial abilities should be able to conceptualize the processes of diffusion in animation more completely or to a greater depth of elaboration (Hay, 1996). Individual differences in the use of their perception and judgment have become an indicator for analyzing students' learning patterns, especially in hypermedia learning environments. It therefore seems useful to determine whether the use of visual strategies produces different effects on different learner groups. The ultimate aim is to design learning materials optimized for the preferred modes of presentation among groups with differing characteristics to improve their performance. How users evolve an appropriate strategy during the process of learning is also highlighted in the study. Static and Dynamic Graphics Park and Hopkins (1993) use the terms "static visual display" and "dynamic visual display" to differentiate between the use of graphics and animation. From their definition, "graphics" refers to representations that do not rely solely on the use of text or numbers to provide informational content, while animation is the combination of a series of graphics and motions to form a visual scenario to represent information. Rieber & Hannafin (1988) define animation as a series of rapidly changing computer screen displays that represent the illusion of movement. In recent years, the increased availability of design tools has also permitted the design of instructional materials that incorporate unlimited variations and forms of verbal and visual information for presentation (Rieber, 1995). The representation of motion provides potential learning interest and stimulates viewer's attention. The effectiveness of the use of animation is confirmed only when appropriate learning content is provided. …

Abstract: Realistic image synthesis provides principles and techniques for creating realistic imagery based on models of real-world objects and behaviors. It has widespread applications in 3D design, computer animation, and scientific visualization. While it is common to describe light and objects in terms of colors, this approach is not sufficiently accurate and cannot render many spectral phenomena such as interference and diffraction. Many researchers have explored spectral rendering and proposed several methods for spectral representation, but none satisfy all representation criteria such as accuracy, compactness and efficiency. Furthermore, previous studies have focused on distinct behaviors of natural phenomena but few on their commonality and generality, and it is difficult to combine existing algorithms to simulate complex processes. This thesis proposes solutions to these problems within a spectrum-based rendering framework. The pipeline begins by loading spectra from a database to specify light sources and objects, then generates a spectral image based on local and global illumination models, projects the spectral image into a CIE image, and finally converts the CIE image into an RGB image for display or a CIELab image for evaluation. In spite of omitting the light phase information, it is shown that this approach suffices to generate all optical effects important for realistic image synthesis. As components of the new framework, a heuristic method is proposed for deriving spectra from colors and an error metric is provided for evaluating synthesized images. The new spectral representation proposed in this thesis is called the composite model. Its key point is to decompose any spectrum into a smooth background and a collection of spikes. The smooth part can be represented by Fourier coefficients and a spike by its location and height. A re-sampling technique is proposed to improve performance. Based upon the characteristics of human perception, the sufficiency of a low-dimensional representation is shown analytically. This model improves upon existing methods with aspect to accuracy, compactness and efficiency, and offers an effective vehicle for rendering optical effects involving spiky spectra. Using the proposed framework and composite spectral model, this thesis develops new illumination models for rendering a number of optical effects including dispersion, interference, diffraction, fluorescence, and volume absorption. The rendered images closely correspond to their real-world counterparts. Overall, this thesis improves realistic image synthesis by expanding its rendering capabilities. It may serve as a basis for a more sophisticated rendering environment for high-quality computer image generation.

Abstract: We show that traditional waveform coding and 3-D model-based coding are not competing alternatives, but should be combined to support and complement each other. Both approaches are combined such that the generality of waveform coding and the efficiency of 3-D model-based coding are available where needed. The combination is achieved by providing the block-based video coder with a second reference frame for prediction, which is synthesized by the model-based coder. The model-based coder uses a parameterized 3-D head model, specifying the shape and color of a person. We therefore restrict our investigations to typical videotelephony scenarios that show head-and-shoulder scenes. Motion and deformation of the 3-D head model constitute facial expressions which are represented by facial animation parameters (FAPs) based on the MPEG-4 standard. An intensity gradient-based approach that exploits the 3-D model information is used to estimate the FAPs, as well as illumination parameters, that describe changes of the brightness in the scene. Model failures and objects that are not known at the decoder are handled by standard block-based motion-compensated prediction, which is not restricted to a special scene content, but results in lower coding efficiency. A Lagrangian approach is employed to determine the most efficient prediction for each block from either the synthesized model frame or the previous decoded frame. Experiments on five video sequences show that bit rate savings of about 35% are achieved at equal average peak signal-to-noise ratio (PSNR) when comparing the model-aided codec to TMN-10, the state-of-the-art test model of the M.263 standard. This corresponds to a gain of 2-3 dB in PSNR when encoding at the same average bit rate.

Abstract: A method for providing 3D animation via a network in a client/server computer system. A 3D model is accessed on the client. The client then receives a series of transform updates for the 3D model via a network. The series of transform updates described for the client the manner in which to update the 3D model to implement the animation. Each of the series of transform updates are applied by the client to the 3D model to render a corresponding series of 3D images. The series of rendered 3D images are then displayed to the user to provide a 3D animation. The transform updates are streamed from the server to the client via the network. Streaming the transform updates across the network is more bandwidth efficient than streaming images. Interactivity is implemented by receiving user commands from the client via the network. In response to the user commands, the server appropriately alters the series of transform updates streamed to the user, thereby providing interactivity to the 3D animation.

Abstract: The author discusses the ten top problems of computer graphics, including topics such as geometric modeling, computer animation, creative information visualization and pixels.

Abstract: In computer animation a system and method for portraying animated characters which convey human-like emotions, by body movements, and human-like body movements. The gestures, for example, arm movements, are synthesized using controlled stochastic functions.

Abstract: The design of autonomous characters capable of planning their own motions continues to be a challenge for computer animation. We present a novel kinematic motion planning algorithm for character animation which addresses some of the outstanding problems. The problem domain for our algorithm is as follows: given a constrained environment with designated handholds and footholds, plan a motion through the environment towards a desired goal. Our algorithm is based on a stochastic search procedure which is guided by a combination of geometric constraints, posture heuristics, and distance-to-goal measures. The method provides a single framework for the use of multiple modes of locomotion in planning motions through constrained, unstructured environments. We illustrate our results with demonstrations of a human character using walking, swinging, climbing, and crawling in order to navigate through complex environments.

Abstract: This paper describes techniques for extracting bitmaps of facial parts from videos of a talking person. The goal is to synthesize photo-realistic talking heads of high quality that show picture-perfect appearance and realistic head movements with good lip-sound synchronization. For the synthesis of a talking head, bitmaps of facial parts are combined to form whole heads and then sequences of such images are integrated with audio from a text-to-speech synthesizer. For a seamless integration of facial parts into an animation, their shape and visual appearance must be known with high accuracy. The recognition system has to find not only the locations of facial features, but must also be able to determine the head's orientation and recognize the facial expressions. Our face recognition proceeds in multiple steps, each with an increased precision. Using motion, color and shape information, the head's position and the location of the main facial features are determined first. Then smaller areas are searched with matched filters, in order to identify specific facial features with high precision. From this information a head's 3D orientation is calculated. Facial parts are cut from the image and, using the head's orientation, are warped into bitmaps with 'normalized' orientation and scale.

Abstract: With increased use of multimedia and computers in education, the use of animation to illustrate dynamics is becoming more commonplace. Previous research suggests that diagrams may reduce cognitive processing as all information is perceptually available, making it more explicit and therefore requiring less inferencing (e.g. Simon and Larkin 1987). Animation, therefore, may be expected to enhance learning, especially when illustrating dynamic processes, as motion is depicted more visually explicitly, thus reducing cognitive processing. However, although animation may increase explicit perceptually available information, it may not automatically improve understanding. Visual explicitness itself does not necessarily guarantee accurate perception of specific information, nor does perception of information guarantee comprehension. Initial studies suggest that certain characteristics of diagrammatic animation have significant effects on cognitive interaction with material and therefore on comprehension. Current computer technology not only enables improved graphical animated illustration, but also provides the facility to physically interact with information on the screen. This in itself may influence the kind of learning that takes place. This paper presents research investigating how different ways of both representing and interacting with animated diagrams influence the kinds of cognitive interactions that may take place.

Abstract: These last years, deformable models raised much interest and found various applications in the field of computer vision. They provide an extensible framework to reconstruct shapes. Deformable surfaces, in particular, are used to represent 3D objects. They have been used for pattern recognition [47,2], computer animation [118], geometric modelling [40,75], simulation [45], boundaries tracking [14], segmentation [83], etc. In this report we propose a deformable surfaces survey. Many surface representation have been proposed to meet different 3D reconstruction problem requirements. We try to classify the main representations proposed in the literature and we study the effect of the representation on the model evolution behavior, revealing some similarities between different approaches. Whe then focus on a powerful discrete mesh representation, the simplex meshes. We propose different algorithms to control simplex meshes shape and topology. Whe show results on 3D medical images segmentation.

Abstract: Algorithm animation attempts to explain an algorithm by visualizing interesting events of the execution of the implemented algorithm on some sample input. Algorithm explanation describes the algorithm on some adequate level of abstraction, states invariants, explains how important steps of the algorithm preserve the invariants, and abstracts from the input data up to the relevant properties. It uses a small focus onto the execution state. This paper is concerned with the explanation of algorithms on linked data structures. The thesis of the paper is that shape analysis of such algorithms produces abstract representations of such data structures, which focus on the "active" parts, i.e., the parts of the data structures, which the algorithm can access during it's next steps. The paper presents a concept of visually executing an algorithm on these abstract representations of data.

Abstract: Using realistic face models and photometric modeling techniques, we present a visual feedback loop that tracks a face, without any marker or controlled lighting, throughout a video sequence and precisely recovers the face position and orientation. We also propose animation techniques to embed realistic expressions in our 3D clones. Such face models permit automatic construction of appearance models.

Abstract: Static mixed-mode presentations consisting of verbal explanations illustrated with diagrams have long been used to communicate information. With the advent of multimedia, such presentations have become dynamic, by migrating from paper to the computer and by adding interactivity and animation. The conventional wisdom is that computer-based multimedia presentations are better than printed presentations. However, does the communicative power of mixed-mode representations stem from their careful design to match cognitive processes involved in comprehension or from their interactive and animated nature? This is an important issue that has never been investigated. This paper first presents a cognitive model of comprehension of mixed-mode representations. We describe how this model generates design guidelines for mixed-mode representations that present expository material in two domains - the concrete domain of mechanical systems and the abstract domain of computer algorithms. We then report on a series of studies that compared computer-based interactive multimedia presentations and their paper-based counterparts. Both were designed in accordance with the comprehension model and were compared against each other and against competing representational forms such as books, CD-ROMs, and animations. These studies indicate that the effectiveness of mixed-mode presentations has more to do with their match with comprehension processes than the medium of presentation. In other words, benefits of interactivity and animation are likely being overstated in the current milieu of fascination with multimedia.

Abstract: We are developing paradigms and algorithms for browsing and editing families of animation using a haptic force-feedback device called a Phantom. These techniques may be generalized to navigation of any high degree-of-freedom system from a lower degree-of-freedom control space, with applications to telerobotics and simulation of virtual humans. We believe that modeling the animation configuration space coupled with the highly interactive nature of the haptic device provides one with useful and intuitive means of control. We have implemented our ideas in a system for the manipulation of animation motion capture data; in particular, anthropomorphic figures with 57 degrees of freedom are controlled by the user in real time. We treat trajectories, which encode animation, as first-class objects; haptic manipulation of these trajectories results in change to the animation. We have several haptic editing modes in which these trajectories are either haptically deformed or performed by the user with expressive control subject to dynamic haptic constraints.

Abstract: This paper introduces a method that can generate continuous human walking motion automatically on an arbitrary path in a three-dimensional (3D) modelled scene. The method is based on a physical approach that solves the boundary value problem. In the motion generation stage, natural-looking walking motion, which includes plane walking, walking upstairs and downstairs and walking on a curved path, is created by applying dynamics and kinematics. The human body is approximated as a simple rigid skeleton model, and dynamic motion is created based on the ground reaction force of the human foot. To adapt to the 3D environment, the 3D walking path is divided into steps which are tagged with the parameters needed for motion generation, and step-by-step motion is connected end-to-end. Additional features include fast calculation and a reduced need for user control. The proposed method can produce interesting human motion and can create realistic computer animation scenes. Copyright © 2000 John Wiley & Sons, Ltd.

Abstract: Methods for defining smooth and continuous coordinate systems in a volume comprised of a lattice structure of guide columns derived from arbitrarily modeled surface topologies involving polygons, nurbs, linear segments, and subdivision surfaces. Applications of these techniques in computer graphics and computer animation include: (1) the definition of pseudo-coordinate systems for use in creating geometry which must grow from said surface (2) the creation of a highly stable coordinate system involving guide columns in which Cartesian physical simulations may be carried out and rendered as well as deformed and rerendered if desired.

Abstract: This and the accompanying paper present an overview of the face and body animation object in the MPEG-4 Version 2 standard. The MPEG-4 standard includes the representation, compression of virtual human models and their interface with other MPEG-4 objects, with bit rate requirements as low as 1 Kbit/second. In this paper we give an overview of geometrical modeling techniques for the FBA object, and in the accompanying paper we describe the animation techniques.