N Magnenat Thalmann

Implementing fast cloth simulation with collision response

The article details and implements efficient techniques for cloth simulation, both in the area of numerical simulation and the area of collision detection and response. Emphasis is put on the efficient implementation of implicit numerical methods with many improvements toward better realism, as well as computation simplicity. A constraint based collision response scheme is adapted to this scheme in order to provide an accurate and stable collision response.

Nonverbal communication interface for collaborative virtual environments

Nonverbal communication is an important aspect of real-life face-to-face interaction and one of the most efficient ways to convey emotions, therefore users should be provided the means to replicate it in the virtual world. Because articulated embodiments are well suited to provide body communication in virtual environments, this paper first reviews some of the advantages and disadvantages of complex embodiments. After a brief introduction to nonverbal communication theories, we present our solution, taking into account the practical limitations of input devices and social science aspects. We introduce our sample of actions and implementation using our VLNET (Virtual Life Network) networked virtual environment and discuss the results of an informal evaluation experiment.

A biomechanical musculoskeletal model of human upper limb for dynamic simulation

In this paper, we provide the biomechanical model of human upper limb we have designed and applied to the three-dimensional left human arm reconstructed from the visible human imaging dataset. This model includes the mechanical properties for bones, joints and muscles lines of action. This work has been done as a part of the European Esprit Project CHARM. Its objective is to develop a comprehensive human animation resource model allowing the dynamic simulation of complex musculoskeletal systems, including finite element deformation of soft-tissues and muscular contraction. In our approach, simplifications have been done so as to ensure the feasibility of the project while preserving the biomechanical validity of the model.

3D Interactive Topological Modeling using Visible Human Dataset

Availability of Visible Human Dataset (VHD)has provided numerous possibilities for its exploitation in both medical applications and 3D animation. In this paper, we present our interactive tools which enable extraction of surfaces for different organs, including bones, muscles, fascia, and skin, from the VHD. The reconstructed surfaces then are used for defining the inter‐relationship of organs, a process we refer to as topological modeling. A data base is constructed, which encapsulates structural, topological, mechanical and other relevant information about organs. A 3D interactive tool enables the building and editing of this data base. Such a data base can later be used for different applications in fields such as medicine, sports, education, and entertainment.

Skin aging estimation by facial simulation

We propose a layered facial simulation model for skin aging with wrinkles, which includes muscle, connective tissue and skin layer. Our aim is to simulate relevant facial animation and aging with the guidance of general facial tissue anatomy, so that the model can be extended to medical and cosmetic applications. B-spline muscle patches are automatically adapted to each individual face by mapping the anatomical facial muscle image. Connective tissues are simulated as simple springs with the length of hypodermis thickness that constrain skin movement. Facial skin deformation and aging are estimated based on an elaborated biomechanical model considering large strain deformation and wrinkle formation. Finally, multi-layered color and bump texture mapping are used to represent wrinkle forms and to render an aged face.

Modelling Facial Communication Between an Animator and a Synthetic Actor in Real Time

This paper describes methods for acquiring and analyzing in real-time the motion of human faces. It proposes a model based on the use of snakes and image processing techniques. It explains how to generate real-time facial animation corresponding to the recorded motion. It also proposed a strategy for the communication between animators and synthetic actors.

Computer graphics and animation

This article surveys the theory and techniques of computer graphics and animation. The main topics are modeling primitives, transformations and colors, visible surface algorithms, light and shadows, ray-tracing, texture, phenomena modeling, principles of computer animation, classification of computer animation methods, key-frame animation, and animation of synthetic actors.

Virtual humans in CyberDance

This paper presents an account of a Cyberdance performance involving both real and virtual dancers. Preparing for this performance required the integration of a number of virtual human modules into a single system framework capable of handling all aspects of the show. We describe the modules that deal with creation, modeling and texturing the virtual humans, as well as those that manage the animation of bodies within real-time applications, and control several bodies simultaneously, as choreographed. Real-time hand deformation and facial animation modules increase the realism of the virtual dancers. Two techniques are described for improving the quality of the rendering in the virtual component of the scenario. We describe the VR devices for merging the interactive dancers into the virtual environment. In conclusion, we report on experiences during the actual presentation of the show and suggest topics for future research into improvements of various parts of our system.

Facial Interaction for Human Machine Interface

Interaction in graphical systems is becoming more and more multimodal. Use of the conventional mode of 2D widget-mouse or keyboard interaction is not very natural for many applications. For the comfort of disabled persons who may not be able to use the hand input devices, it is necessary to explore means for interactive controls for them. In this paper, we discuss real time interaction through facial input and face-to-face communication in a virtual dialogue. The paper presents our method of extracting dynamic facial movements which can be hooked as controls for a desired application. For example, in performance driven facial animation, the method enables recognition of facial expressions of a real person which are appropriately mapped as controlling parameters to simulate facial expressions of a synthetic actor in real time. In other applications, the extracted parameters can provide real time estimates of positions and orientations in a virtual scene. The method requires a video camera input and extracts motion parameters through a small set of visually tracked feature points. In the face-to-face virtual dialogue, recognition acts like a module for acquiring emotional states of a real actor. This can be integrated with other modules for the interpretation of the response with voice and emotions of the virtual actor. This gives potential for an interface system with human like agent interacting with user in spoken language with facial expressions.