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Item Simulation of Facial Muscle Actions Based on Rational Free Form Deformations(Blackwell Science Ltd and the Eurographics Association, 1992) Kalra, Prem; Mangili, Angelo; Thalmann, Nadia Magnenat; Thalmann, DanielThis paper describes interactive facilities for simulating abstract muscle actions using Rational Free Form Deformations (RFFD). The particular muscle action is simulated as the displacement of the control points of the control-unit for an RFFD defined on a region of interest. One or several simulated muscle actions constitute a Minimum Perceptible Action (MPA), which is defined as the atomic action unit, similar to Action Unit (AU) of the Facial Action Coding System (FACS), to build an expression.Item A Flexible Architecture for Virtual Humans in Networked Collaborative Virtual Environments(Blackwell Publishers Ltd and the Eurographics Association, 1997) Sunday Pandzic, Igor; Lee, Elwin; Magnenat Thalmann, Nadia; Capin, Tolga K.; Thalmann, DanielComplex virtual human representation provides more natural interaction and communication among participants in networked virtual environments, hence it is expected to increase the sense of being together within the same virtual world. We present a flexible framework for the integration of virtual humans in networked collaborative virtual environments. A modular architecture allows flexible representation and control of the virtual humans, whether they are controlled by a physical user using all sorts of tracking and other devices, or by an intelligent control program turning them into autonomous actors. The modularity of the system allows for fairly easy extensions and integration with new techniques making it interesting also as a testbed for various domains from "classic" VR to psychological experiments. We present results in terms of functionalities, example applications and measurements of performance and network traffic with an increasing number of participants in the simulation.Item An Informed Environment Dedicated to the Simulation of Virtual Humans in Urban Context(Blackwell Publishers Ltd and the Eurographics Association, 1999) Farenc, Nathalie; Boulic, Ronan; Thalmann, DanielIn this paper, we outline the creation of an Informed Environment, dedicated to urban life simulation.We propose methods and tools for creating and providing the information necessary for animating virtual humans in a city using an Informed Environment. The Informed Environment is based on a hierarchical decomposition of a urban scene into Environment Entities providing geometrical information as well as semantic notions, thus allowing a more realistic simulation of human behaviour. In this manner, virtual humans can integrate with a certain kind of urban knowledge.Item An Efficient and Flexible Perception Pipeline for Autonomous Agents(Blackwell Publishers Ltd and the Eurographics Association, 1999) Bordeux, Christophe; Boulic, Ronan; Thalmann, DanielAgents in virtual environments require a combination of perception and action to behave in an autonomous way. We extend a software architecture for the management of actions blending, called AGENTlib, with a perception mechanism. The perception system provides a uniform interface to various techniques in the field of virtual perception, including synthetic vision, database access and perception persistency. We describe the framework we designed to efficiently filter valuable information from the scene and we address concerns about computation redundancy and data propagation through multiple filtering modules.Item A Hand Control and Automatic Grasping System for Synthetic Actors(Blackwell Science Ltd and the Eurographics Association, 1994) Sanso, Ramon Mas; Thalmann, DanielIn the computer animation field, the interest for grasping has appeared with the development of synthetic actors. Based on a grasp taxonomy, we propose a completely automatic grasping system for synthetic actors. In particular, the system can decide to use a pinch when the object is too small to be grasped by more than two fingers or to use a two-handed grasp when the object is too large. The system also offers both direct and inverse kinematics to control the articulations. In order to ensure realistic looking closing of the hand, several of the joints are constrained. A brief description of the system and results are also presented.Item Combined Direct and Inverse Kinematic Control for Articulated Figure Motion Editing(Blackwell Science Ltd and the Eurographics Association, 1992) Boulic, Ronan; Thalmann, DanielA new approach for the animation of articulated figures is presented. We propose a system of articulated motion design which offers a full combination of both direct and inverse kinematic control of the joint parameters. Such an approach allows an animator to specify interactively goal-directed changes to existing sampled joint motions, resulting in a more general and expressive class of possible joint motions. The fundamental idea is to consider any desired-joint space motion as a reference model inserted into the secondary task of an inverse kinematic control scheme. This approach profits from the use of half-space Cartesian main tasks in conjunction with a parallel control of the articulated figure called the coach-trainee metaphor. In addition, a transition function is introduced so as to guarantee the continuity of the control. The resulting combined kinematic control scheme leads to a new methodology of joint-motion editing which is demonstrated through the improvement of a functional model of human walking.Item An Adaptive Spatial Subdivision of the Object Space for Fast Collision Detection of Animated Rigid Bodies(Blackwell Science Ltd and the Eurographics Association, 1995) Bandi, Srikanth; Thalmann, DanielCollision detection tests between objects dominate run time simulation of rigid body animation. Traditionally, hierarchical bounding box tests are used to minimize collision detection time. But the bounding boxes do not take shapes of the objects into account which results in a large number of collision detection tests. We propose an adaptive spatial subdivision of the object space based on octree structure to rectify this problem. We also present a technique for efficiently updating this structure periodically during the simulation.Item An Integrated System for Modeling, Animating and Rendering Hair(Blackwell Science Ltd and the Eurographics Association, 1993) Daldegan, Agnes; Thalmann, Nadia Magnenat; Kurihara, Tsuneya; Thalmann, DanielThere are basically four problems to solve in order to produce realistic animated synthetic actors with hair: hair modeling and creation, hair motion, collision detection and hair rendering. This paper describes a complete methodology to solve these basic four problems. We present how hair styles may be designed with our Hair Styler module. Then we survey the animation model and emphasize a method of collision processing. Finally, we explain how hair may be rendered using an extension of a standard ray-tracing program. We also show applications of our synthetic actors with various hair styles and different styles of mustaches and beards.Item Space Discretization for Efficient Human Navigation(Blackwell Publishers Ltd and the Eurographics Association, 1998) Bandi, Srikanth; Thalmann, DanielThere is a large body of research on motion control of legs in human models. However, they require specification of global paths in which to move. A method for automatically computing a global motion path for a human in 3D environment of obstacles is presented. Object space is discretized into a 3D grid of uniform cells and an optimal path is generated between two points as a discrete cell path. The grid is treated as graph with orthogonal links of uniform cost. A' search method is applied for path finding. By considering only the cells on the upper surface of objects on which human walks, a large portion of the grid is discarded from the search space, thus boosting efficiency. This is expected to be a higher level mechanism for various local foot placement methods in human animation.Item 8th Eurographics Workshop on Computer Animation and Simulation(Blackwell Publishers Ltd and the Eurographics Association, 1998) Thalmann, Daniel; Van De Panne, Michiel