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Item The Use of Finite Element Theory for Simulating Object and Human Body Deformations and Contacts(Eurographics Association, 1989) Gourret, Jean-Paul; Magnenat-Thalmann, Nadia; Thalmann, DanielThis paper presents a method for combining image synthesis and modeling based on a finite element method (FEM) to get realistic intelligent images. FEM is used for modeling both elastically and plastically deformations of objects, and impacts with or without penetration between deformable objects. The concept of deformable objects is applied to human flesh to improve the behavior of synthetic human grasping and walking. The paper also discusses the introduction of this method in an animation system based on the concept of "intelligent" synthetic actors with automatic motion control performed using A.I. and robotics techniques. In particular, motion is planned at a task level and computed using physical laws.Item Visyllable Based Speech Animation(Blackwell Publishers, Inc and the Eurographics Association, 2003) Kshirsagar, Sumedha; Magnenat-Thalmann, NadiaVisemes are visual counterpart of phonemes. Traditionally, the speech animation of 3D synthetic faces involvesextraction of visemes from input speech followed by the application of co-articulation rules to generate realisticanimation. In this paper, we take a novel approach for speech animation - using visyllables, the visual counterpartof syllables. The approach results into a concatenative visyllable based speech animation system. The key contributionof this paper lies in two main areas. Firstly, we define a set of visyllable units for spoken English along withthe associated phonological rules for valid syllables. Based on these rules, we have implemented a syllabificationalgorithm that allows segmentation of a given phoneme stream into syllables and subsequently visyllables. Secondly,we have recorded the database of visyllables using a facial motion capture system. The recorded visyllableunits are post-processed semi-automatically to ensure continuity at the vowel boundaries of the visyllables. We defineeach visyllable in terms of the Facial Movement Parameters (FMP). The FMPs are obtained as a result of thestatistical analysis of the facial motion capture data. The FMPs allow a compact representation of the visyllables.Further, the FMPs also facilitate the formulation of rules for boundary matching and smoothing after concatenatingthe visyllables units. Ours is the first visyllable based speech animation system. The proposed technique iseasy to implement, effective for real-time as well as non real-time applications and results into realistic speechanimation.Categories and Subject Descriptors (according to ACM CCS): 1.3.7 [Computer Graphics]: Three-Dimensional Graphics and RealismItem Modeling Dynamic Hair as a Continuum(Blackwell Publishers Ltd and the Eurographics Association, 2001) Hadap, Sunil; Magnenat-Thalmann, NadiaIn this paper we address the difficult problem of hair dynamics, particularly hair-hair and hair-air interactions. To model these interactions, we propose to consider hair volume as a continuum. Subsequently, we treat the interaction dynamics to be fluid dynamics. This proves to be a strong as well as viable approach for an otherwise very complex phenomenon. However, we retain the individual character of hair, which is vital to visually realistic rendering of hair animation. For that, we develop an elaborate model for stiffness and inertial dynamics of individual hair strand. Being a reduced coordinate formulation, the stiffness dynamics is numerically stable and fast. We then unify the continuum interaction dynamics and the individual hair's stiffness dynamics.Item Real-time Animation of Dressed Virtual Humans(Blackwell Publishers, Inc and the Eurographics Association, 2002) Cordier, Frederic; Magnenat-Thalmann, NadiaIn this paper, we describe a method for cloth animation in real-time. The algorithm works in a hybrid manner exploiting the merits of both the physical-based and geometric deformations. It makes use of predetermined conditions between the cloth and the body model, avoiding complex collision detection and physical deformations wherever possible. Garments are segmented into pieces that are simulated by various algorithms, depending on how they are laid on the body surface and whether they stick or flow on it. Tests show that the method is well suited to fully dressed virtual human models, achieving real-time performance compared to ordinary cloth-simulations.Item Generating Animatable 3D Virtual Humans from Photographs(Blackwell Publishers Ltd and the Eurographics Association, 2000) Lee, WonSook; Gu, Jin; Magnenat-Thalmann, NadiaWe present an easy, practical and efficient full body cloning methodology. This system utilizes photos taken from the front, side and back of a person in any given imaging environment without requiring a special background or a controlled illuminating condition. A seamless generic body specified in the VRML H-Anim 1.1 format is used to generate an individualized virtual human. The system is composed of two major components: face-cloning and body-cloning. The face-cloning component uses feature points on front and side images and then applies DFFD for shape modification. Next a fully automatic seamless texture mapping is generated for 360? coloring on a 3D polygonal model. The body-cloning component has two steps: (i feature points specification, which enables automatic silhouette detection in an arbitrary background (ii two-stage body modification by using feature points and body silhouette respectively. The final integrated human model has photo-realistic animatable face, hands, feet and body. The result can be visualized in any VRML compliant browser.Item The Problematics of Human Prototyping and Animation(Blackwell Publishing Ltd and the Eurographics Association, 1989) Magnenat-Thalmann, Nadia; Thalmann, DanielSeveral ideas and experiments are presented for the creation and realistic animation of three-dimensional scenes involving human beings conscious of their environment. The various approaches should allow the intelligent creation of human beings using prototypes and generate their animation based on mechanics, artificial intelligence and robotics. This paper discusses the problems involved in three major steps of the simulation of human beings: the creation of the human shapes, the motion of the human skeleton, and the deformation of the surfaces. Several examples are presented illustrating positional constraints, dynamics, behavioural animation and finite element theory.Item A Data-Driven Approach for Real-Time Clothes Simulation(The Eurographics Association and Blackwell Publishing Ltd., 2005) Cordier, Frederic; Magnenat-Thalmann, NadiaA data-driven approach for the real-time processing of clothes, particularly suitable for simulating dresses worn by virtual characters, is proposed. It starts, prior to real-time simulation, by analyzing cloth behavior in relation to the underlying skeleton movement from a presimulated sequence of the cloth obtained using any high-quality off-line simulators. The idea is to use this analysis to find an optimal combination of physics-based simulation and geometric approximation of the simulator; potentially colliding regions are defined on the cloth such that they will hold true for the skeleton movement that closely matches that of presimulated sequence. At runtime, using these analyses, our simulation process provides both visually pleasing results and performance, as long as the motion of the character remains sufficiently close to the original sequence used for the precomputation.The key contributions of this paper are (1) efficient collision handling that prunes out potentially colliding objects by using the off-line simulation sequence as examples; (2) data-driven fix-up process for the coarse mesh simulation that deduces the gross behavior of the cloth; and (3) geometric approximation of the fine mesh deformation, responsible for details in the shape of the cloth such as wrinkles.