Laurent Moccozet

Real-time animation of realistic virtual humans

The authors have been working on simulating virtual humans for several years. Until recently, these constructs could not act in real time. Today, however, many applications need to simulate in real time virtual humans that look realistic. They have invested considerable effort in developing and integrating several modules into a system capable of animating humans in real-time situations. This includes interactive modules for building realistic individuals and a texture-fitting method suitable for all parts of the head and body. Animating the body, including the hands and their deformations, is the key aspect of the system; to their knowledge, no competing system integrates all these functions. They also included facial animation, as demonstrated below with virtual tennis players. They have developed a single system containing all the modules needed for simulating real-time virtual humans in distant virtual environments (VEs). The system lets one rapidly clone any individual and animate the clone in various contexts. People cannot mistake virtual humans for real ones, but they think them recognizable and realistic.

The HUMANOID Environment for Interactive Animation of Multiple Deformable Human Characters

We describe the HUMANOID environment dedicated to human modeling and animation for general multimedia, VR, and CAD applications integrating virtual humans. We present the design of the system and the integration of the various features: generic modeling of a large class of entities with the BODY data structure, realistic skin deformation for body and hands, facial animation, collision detection, integrated motion control and parallelization of computation intensive tasks.

Simulating wrinkles and skin aging

We describe a methodology and framework to simulate facial animation and skin aging, taking into account skin texture and wrinkle dynamics. We split the facial simulation process into facial surface deformation and wrinkle generation. The first of these is based on a three-layered facial structure (muscle, connective tissue, and skin layers). The layer of B-spline patch muscles provides the relevant contraction forces to enable the skin deformation, while the layer of connective tissues constrains the range of skin movement. The wrinkle generation uses a synthetic texture, and wrinkles are formed dynamically, thanks to a linear plastic model. The wrinkle generation and rendering can be incorporated into real-time facial animation systems.

An ontology of virtual humans: Incorporating semantics into human shapes

Most of the efforts concerning graphical representations of humans (Virtual Humans) have been focused on synthesizing geometry for static or animated shapes. The next step is to consider a human body not only as a 3D shape, but as an active semantic entity with features, functionalities, interaction skills, etc. We are currently working on an ontology-based approach to make Virtual Humans more active and understandable both for humans and machines. The ontology for Virtual Humans we are defining will provide the “semantic layer” required to reconstruct, stock, retrieve, reuse and share content and knowledge related to Virtual Humans.

Anatomical modelling of the musculoskeletal system from MRI

This paper presents a novel approach for multi-organ (musculoskeletal system) automatic registration and segmentation from clinical MRI datasets, based on discrete deformable models (simplex meshes). We reduce the computational complexity using multi-resolution forces, multi-resolution hierarchical collision handling and large simulation time steps (implicit integration scheme), allowing real-time user control and cost-efficient segmentation. Radial forces and topological constraints (attachments) are applied to regularize the segmentation process. Based on a medial axis constrained approximation, we efficiently characterize shapes and deformations. We validate our methods for the hip joint and the thigh (20 muscles, 4 bones) on 4 datasets: average error = 1.5 mm, computation time = 15 min.

Emotional face expression profiles supported by virtual human ontology

Expressive facial animation synthesis of human like characters has had many approaches with good results. MPEG‐4 standard has functioned as the basis of many of those approaches. In this paper we would like to lay out the knowledge of some of those approaches inside an ontology in order to support the modeling of emotional facial animation in virtual humans (VH). Inside this ontology we will present MPEG‐4 facial animation concepts and its relationship with emotion through expression profiles that utilize psychological models of emotions. The ontology allows storing, indexing and retrieving prerecorded synthetic facial animations that can express a given emotion. Also this ontology can be used a refined knowledge base in regards to the emotional facial animation creation. This ontology is made using Web Ontology Language and the results are presented as answered queries. Copyright

Accurate simulation of hip joint range of motion

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.

A numeric model to simulate solar individual ultraviolet exposure.

Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time‐consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.

Hip joint modeling for the control of the joint center and the range of motions

Abstract This paper presents a medical visualization tool implementing a hip joint modeling method that offers the control of the hip joint center and the assessment of the hip range of motions. As the shape of the femoral head is not a perfect sphere, it is in fact close to a 3D conchoid shape, the resulting articulation center cannot be modeled as the center of the sphere that best approximates the femoral head. In order to correctly assess the range of motion of a patients hip, the medical doctor cannot proceed with such an approximation method. An automatic computation methodology of the hip joint center location is being designed and implemented based on the shape of the acetabular rim. And more, the extreme ranges of motions are calculated on the bony hip model.

Simulating Virtual Humans in Networked Virtual Environments

In the past decade, networked virtual environments (NVEs) have been an increasingly active area of research, with the first commercial systems emerging recently. Graphical and behavioral representation of users within such systems is a particularly important issue that has lagged in development behind other issues such as network architectures and space structuring. In this paper, we expose the importance of using virtual humans within these systems and provide a brief overview of several virtual humans technologies used in particular for simulation of crowds. As the main technical contribution, the paper presents the integration of these technologies with the COVEN-DIVE platform, the extension of the DIVE system developed within the COVEN project. In conjunction with this, we present our contributions through the COVEN project to the MPEG-4 standard concerning the representation of virtual humans.