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Computer Animation, 2002. Proceedings of

Date 21-21 June 2002

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  • Proceedings of Computer Animation 2002 (CA 2002)

    Publication Year: 2002
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (405 KB)  

    The following topics are dealt with: facial animation; virtual heritage and natural phenomena; virtual reality; image-based modeling and animation; database systems for animation; standards for human animation; autonomous characters and behavioral animation; digital media communication; simulation of clothes; medical applications; and motion retargeting. View full abstract»

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  • Author index

    Publication Year: 2002 , Page(s): 271
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    Freely Available from IEEE
  • Model-based animation of co-verbal gesture

    Publication Year: 2002 , Page(s): 252 - 257
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (543 KB) |  | HTML iconHTML  

    Virtual conversational agents are supposed to combine speech with non-verbal modalities for intelligible and believable utterances. However, the automatic synthesis of co-verbal gestures is still struggling with several problems like naturalness in procedurally generated animations, flexibility in pre-defined movements, and synchronization with speech. In this paper we focus on generating complex multimodal utterances including gesture and speech from XML-based descriptions of their overt form. We describe a coordination model that reproduces coarticulation and transition effects in both modalities. In particular, an efficient kinematic approach to creating gesture animations from shape specifications is presented, which provides fine adaptation to temporal constraints that are imposed by cross-modal synchrony View full abstract»

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  • Building artificial memory to autonomous agents using dynamic and hierarchical finite state machine

    Publication Year: 2002 , Page(s): 164 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (585 KB) |  | HTML iconHTML  

    This paper presents a model for building agents' memories in virtual environments. This approach allows the generation of agents' memory during the simulation, without user intervention. Moreover the memory can be used to generate behavioural reactive rules. We use dynamic and hierarchical finite state machine (DHFSM) in order to represent the agents past experiences View full abstract»

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  • Removing tetrahedra from a manifold mesh

    Publication Year: 2002 , Page(s): 225 - 229
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    One of the most important task in surgical simulation is the ability to cut volumetric organs. Several algorithms have already been described but none of them can actually maintain a specific and important topological property of the mesh called manifoldness. In this article we define the notion of manifoldness and we explain why it is important to preserve it. We propose a new algorithm that maintains manifoldness and that implements a very simple cut strategy: the removing of soft tissue material, which is an efficient way to simulate the action of an ultrasound cautery. Finally, we present experimental results which show the efficiency of this algorithm in a surgery simulation system View full abstract»

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  • Behavioural animation of virtual humans: what kind of laws and rules ?

    Publication Year: 2002 , Page(s): 144 - 153
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1303 KB) |  | HTML iconHTML  

    Interactive systems, games, VR and multimedia systems require more and more flexible Virtual Humans with individualities. Behavioral animation seems to be the best way to develop this kind of applications, but there is still a major problem to select the right laws and rules to implement individual but believable behaviors. To create motion laws, there are mainly two approaches: 1) Recording the motion using motion capture systems, then to try to alternate such a motion to create this individuality. This process is tedious and there is no reliable method at this stage. 2) Creating computational models which are controlled by a few parameters. One of the major problem is to find such models and to compose them to create complex motion. Such models can be created for walking, grasping, but also for groups and crowds View full abstract»

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  • Prototyping and transforming visemes for animated speech

    Publication Year: 2002 , Page(s): 248 - 251
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    Animated talking faces can be generated from a set of predefined face and mouth shapes (visemes) by either concatenation or morphing. Each facial image corresponds to one or more phonemes, which are generated in synchrony with the visual changes. Existing implementations require a full set of facial visemes to be captured or created by an artist before the images can be animated. In this work we generate new, photo-realistic visemes from a single neutral face image by transformation using a set of prototype visemes. This allows us to generate visual speech from photographs and portraits where a full set of visemes is not available View full abstract»

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  • Bilayered approximate integration for rapid and plausible animation of virtual cloth with realistic wrinkles

    Publication Year: 2002 , Page(s): 203 - 211
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (715 KB) |  | HTML iconHTML  

    We present an efficient method for rapid animation of mass-spring model with a large number of mass-points. Realistic cloth simulation requires large amount of time in general. This is not only because the calculation for one step requires much time but also because the cloth simulation easily tends to become unstable. Although the implicit method can make the simulation stable, it is still impossible to generate interactive animation when the number of mass-points is sufficiently large enough to represent realistic wrinkles. An efficient animation method proposed by M. Desbrun (1999) also involves O(n2)-sized matrix so that it cannot be applied to models with a large number of mass-points. A stable approximate method without matrix operations has been introduced by M. Oshita and A. Makinouchi (2001), but its physical correctness is significantly impaired as the stiffness increases or the timestep becomes large. In this paper we propose a bilayered approach for efficient cloth animation with a large number of mass-points. The proposed method uses two mass-spring meshes. One of them is a rough mesh for representing global motion, and the other is a fine mesh for realistic wrinkles. The experimental results show that the method can be successfully used for real-time animation of plausible cloth models. View full abstract»

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  • Spacetime sweeping: an interactive dynamic constraints solver

    Publication Year: 2002 , Page(s): 261 - 270
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    This paper presents a new method for editing an existing motion to satisfy a set of user-specified constraints, and in doing so guaranteeing the kinematic and dynamic soundness of the transformed motion. We cast the motion editing problem as a constrained state estimation problem based on the per-frame Kalman filter framework. To handle various kinds of kinematic and dynamic constraints in a scalable fashion, we develop a new algorithm, called spacetime sweeping, which sweeps through the frames with two consecutive filters. The unscented Kalman (UK) filter estimates an optimal pose for the current frame that conforms to the given constraints, and feeds the result to the least-squares (LS) filter. Then, the LS filter resolves the inter-frame inconsistencies introduced by the UK filter due to the independent handling of the position, velocity and acceleration. The per-frame approach of the space-time sweeping provides a surprising performance gain. Thus editing of motion that involves dynamic constraints, such as dynamic balancing, can be done interactively View full abstract»

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  • Point representation augmented to surface reconstruction in image-based VR

    Publication Year: 2002 , Page(s): 55 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (727 KB) |  | HTML iconHTML  

    In this paper we propose a hybrid representation of environment models by a point representation augmented to geometric representation of surface polygons reconstructed from multiple reference images, through which a real time walkthrough of a complex environment can be achieved. By the method, we start from classification of pixels of the source images into two categories, corresponding respectively to the planar and non-planar surfaces in 3D space. For the pixels corresponding to the planar surfaces, the plane coefficients are reconstructed and all their appearances in the reference images are merged to form uniformly sampled texture images by a comparison of sampling rate and resampling. For the pixels corresponding to the non-planar surfaces, a point representation is applied and the redundant pixels are removed again through sampling rate comparison. The remained pixels are organized by OBB-tree according to their space coordinates. At the same time, the holes that are unable to be captured by all the reference images are pre-filled in the preprocessing phase so that the probability of hole appearance in walkthrough is greatly reduced. Under this hybrid representation, texture mapping and point warping are employed to render the novel views, to take full advantages of the acceleration utility of graphics hardware View full abstract»

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  • Employing approximate 3D models to enrich traditional computer assisted animation

    Publication Year: 2002 , Page(s): 183 - 190
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (932 KB) |  | HTML iconHTML  

    Although computer assistance for traditional animation is gaining a lot of attention during recent years, it still has to cope with many limitations. Part of the current research focuses on employing full 3D input models, which are rendered and even animated in many different non-photorealistic (NPR) styles. Disadvantages are the need to create complicated 3D models and the many difficulties to achieve lively movements. Purely 2D approaches, on the other hand, need many elaborated single drawings. Getting perspective right and retaining volumes are a major problem in that approach to computer assisted traditional animation, due to the complete lack of 3D information. Unfortunately, the employed software is ignorant about the approximate 3D representation in the animator's mind. In this paper, we present a novel tool for traditional animation, based on an approximate 3D model. This tool helps retaining volumes and proportions, and ensures frame-to-frame coherence View full abstract»

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  • CoArt: coarticulation region analysis for control of 2D characters

    Publication Year: 2002 , Page(s): 17 - 22
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (770 KB) |  | HTML iconHTML  

    A facial analysis-synthesis framework based on a concise set of local, independently actuated, coarticulation regions (CRs) is presented for the control of 2D animated characters. CRs are parameterized by muscle actuations and thereby provide a physically meaningful description of face state that is easily abstracted to higher-level descriptions of facial expression. An independent component analysis on a set of training images acquired from an actor is used to characterize the appearance space of each CR. Within this framework actor-independent face reconstruction databases can be created by an artist or extracted from video sequences. In addition, the muscle parameter values may be used to drive any similarly parameterized 3D facial model. The flexibility afforded by such a methodology is demonstrated with applications to 2D facial animation control and sample based video synthesis. The analysis runs in real-time on modest consumer hardware View full abstract»

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  • Homotopic database animation

    Publication Year: 2002 , Page(s): 89 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB) |  | HTML iconHTML  

    Very large databases on the Web have been changing dynamically and have become complicated today. This research aims at helping users' understanding of database changes by database animation. As a case study, animating budget management of one company is researched It shows clearly that database animation help understand the flow of plans and the distribution of the whole budget. Furthermore, it has shown that reverse animation by preserved homotopy realizes the effective reuse of databases View full abstract»

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  • Issues with lip sync animation: can you read my lips?

    Publication Year: 2002 , Page(s): 3 - 10
    Cited by:  Papers (1)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (329 KB) |  | HTML iconHTML  

    Lip-sync animation is complex and challenging. It promises to be important in natural human-computer interfaces and entertainment as well as aid in the education of the deaf. It is an important component in creating a realistic human figure. Speech is based on principles from anatomy, physics, and psychophysiology. We discuss some of the issues that make speech so complex to model visually View full abstract»

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  • AMOBA: a database system for annotating captured human movements

    Publication Year: 2002 , Page(s): 98 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    For the management of a large number of motion data for humanoid virtual actors we propose to use a database system to store and retrieve motion data with additional information. We show key questions lying behind the different classification schemes for human motion. Having obtained these criteria, we deduce the requirements a database has to fulfil for coping different classification schemes. We describe the AMOBA database system which allows to store and retrieve human movement data with an expandable set of classification schemes. To implement classification schemes we annotate movements with specific characteristics View full abstract»

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  • Accurate simulation of hip joint range of motion

    Publication Year: 2002 , Page(s): 215 - 219
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (886 KB) |  | HTML iconHTML  

    This paper presents a hip joint motion simulation method using accurate hip joint center (HJC) and hip range of motion. We calculate the extreme hip joint range of motion centered on the HJC that is located by an automatic calculation algorithm on 3D reconstructed surface models. We make 3D bone surface models from computer tomography or magnetic resonance imaging. The medical objective is to quantify hip kinematics in the function of hip morphology. Since only extreme ranges of motions are evaluated from bones, we can estimate the motions that are restricted by bones impingements by comparing the computed values with real extreme range of motion View full abstract»

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  • Virtual climbing plants competing for space

    Publication Year: 2002 , Page(s): 33 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (674 KB) |  | HTML iconHTML  

    An old algorithm for visual simulation of climbing plants is extended here. Plants are modeled as systems of oriented particles that are able to sense their environment. Particles move to the best locations using directed random walk. We use the phenomenon of traumatic reiteration for critical cases. If there is no location for further growth possible the particle dies, but before that it sends a signal that is propagated down in the plant structure. This signal activates the closest possible sleeping particle that takes its job. We use an associated voxel space for collisions and space occupancy detection as well as for evaluating the illumination of the plant organs. The algorithm is fast, easy to implement, and runs interactively even for quite large scenes on a medium-class computer. We believe that this approach can be used as an interactive technique in architecture, computer games, computer animation, etc View full abstract»

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  • A hybrid dynamical systems approach to intelligent low-level navigation

    Publication Year: 2002 , Page(s): 154 - 163
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    Animated characters may exhibit several kinds of dynamic intelligence when performing low-level navigation (i.e., navigation on a local perceptual scale): they decide among different modes of behavior selectively discriminate entities in the world around them, perform obstacle avoidance, etc. In this paper we present a hybrid dynamical system model of low-level navigation that accounts for the above-mentioned kinds of intelligence. In so doing, the model illustrates general ideas about how a hybrid systems perspective can influence and simplify such reactive/behavioral modeling for multi-agent systems. In addition, we directly employed our formal hybrid system model to generate animations that illustrate our navigation strategies. Overall, our results suggest that hierarchical hybrid systems may provide a natural framework for modeling elements of intelligent animated actors. View full abstract»

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  • Polyhedral object detection and pose estimation for augmented reality applications

    Publication Year: 2002 , Page(s): 65 - 69
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (333 KB) |  | HTML iconHTML  

    In augmented reality applications, tracking and registration of both cameras and objects is required because, to combine real and rendered scenes, we must project synthetic models at the right location in real images. Although much work has been done to track objects of interest, initialization of theses trackers often remains manual. Our work aims at automating this step by integrating object recognition and tracking into an AR system. Our emphasis is on the initialization phase of the tracking. We address all the three major aspects of the problem of model-to-image registration: feature detection, correspondence and pose estimation. We have developed a novel approach based on facet detection that greatly reduces the number of possible feature correspondences making it possible to directly compute the transformation which best maps 3-D object to the image plane. We will argue that this approach offers a one-fold speed-up over existing methods. Results of our AR system which integrates initialization and tracking are shown. Our method takes about 5 seconds on our example images View full abstract»

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  • Conversational virtual character for the Web

    Publication Year: 2002 , Page(s): 240 - 247
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (493 KB) |  | HTML iconHTML  

    Talking virtual characters are graphical simulations of real or imaginary persons capable of human-like behaviour, most importantly talking and gesturing. Coupled with artificial intelligence (AI) techniques, the virtual characters are expected to represent the ultimate abstraction of a human-computer interface, the one where the computer looks, talks and acts like a human. Such an interface would include audio/video analysis and synthesis techniques combined with AI, dialogue management and a vast knowledge base in order to be able to respond quasi-intelligently to the users by: speech, gesture and even mood. While this goal lies further on in the future, we present an architecture that reaches towards it, at the same time aiming for a possibility of practical applications in the nearer future. Our architecture is aimed specifically at the Web. It involves a talking virtual character capable of involving in a fairly meaningful conversation with the user who types in the input View full abstract»

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  • Avenues of research in dynamic clothing

    Publication Year: 2002 , Page(s): 193 - 202
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (598 KB) |  | HTML iconHTML  

    While mechanical cloth simulation systems are widely used for creating draped garments on virtual characters, the animation of virtual garments raise challenges on its own. The perception of garment beauty is first related to the dynamic accuracy of the cloth simulation model, which has to reproduce precisely the dissipative behaviors of the material, such as viscosity and plasticity, rendering the visual features of realistic cloth motion. The other important aspect is the need of adequate techniques for the real-time visualization of animated virtual garments, required for many real-time or interactive applications. This work present techniques yielding visible advances for addressing these two aspects View full abstract»

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  • Knowledge discovery and memory space as asymmetric information-the architecture of the Internet media lab netzspannung.org

    Publication Year: 2002 , Page(s): 173 - 182
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB) |  | HTML iconHTML  

    In this paper we describe the elements of netzspannung.org, an on-line media laboratory as a Competence Centre for digital art, culture and technology. To this end netzspannung.org is being developed as an open distributed toolbox for knowledge discovery and experimentation with networked media resources accompanied by community, information channels and media strategies connecting processes in virtual space with real places. The first online demonstrator of netzspannung.org explores the creation of an architecture for visualising and exploring the interrelations between media art, culture, science aid technology. URL http://netzspannung.org View full abstract»

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  • Evaluating video-based motion capture

    Publication Year: 2002 , Page(s): 75 - 80
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (342 KB) |  | HTML iconHTML  

    Motion capture can be an effective method of creating realistic human motion for animation. Unfortunately, the quality demands for animation place challenging demands on a capture system. To date, capture solutions that meet these demands have required specialized hardware that is invasive and expensive. Computer vision could make animation data much easier to obtain. Unfortunately, current techniques fall short of the demands of animation applications. In this paper, we will explore why the demands of animation lead to a particularly difficult challenge for capture techniques. We present a constraint-based methodology for reconstructing the 3D motion given image observations, and use this as a tool for understanding the problem. Synthetic experiments confirm that these situations would arise in practice. The experiments show how even simple visual tracking information can be used to create human motion but even with perfect tracking, incorrect reconstructions are not only possible but inevitable View full abstract»

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  • Haptics technologies and cultural heritage applications

    Publication Year: 2002 , Page(s): 25 - 32
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB) |  | HTML iconHTML  

    This article describes the architecture of the "Museum of Pure Form", a virtual reality system where the user can interact, through the senses of touch and sight, with digital models of 3D art forms and sculptures. Two different realizations of "Museum. of Pure Form" systems are currently being developed at PERCRO, Pisa, Italy. In one realization "The Museum of Pure Form" is conceived as a system placed inside several museums and art galleries around Europe and made available to people visiting such institutions. In the second realization the system will be placed and tested inside a CAVE environment. Considerations on technological aspects concerning the implementation of a virtual environment endowed with haptic feedback for cultural heritage applications are reported throughout the paper View full abstract»

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  • Making discourse visible: coding and animating conversational facial displays

    Publication Year: 2002 , Page(s): 11 - 16
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    People highlight the intended interpretation of their utterances within a larger discourse by a diverse set of nonverbal signals. These signals represent a key challenge for animated conversational agents because they are pervasive, variable, and need to be coordinated judiciously in an effective contribution to conversation. In this paper we describe a freely-available cross-platform real-time facial animation system, RUTH, that animates such high-level signals in synchrony with speech and lip movements. RUTH adopts an open, layered architecture in which fine-grained features of the animation can be derived by rule from inferred linguistic structure, allowing us to use RUTH, in conjunction with annotation of observed discourse, to investigate the meaningful high-level elements of conversational facial movement for American English speakers View full abstract»

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