Simulation of Individual Spontaneous Reactive Behavior

The context of this work is the search for realism and believability of Virtual Humans. Our contribution to achieve this goal is to enable Virtual Humans (VH) to react to spontaneous events in virtual environments (VE). In order to reflect the individuality of each VH, these reactions have to be expressive and unique. In this paper we present firstly a model of reaction based on personality traits. The model was defined using statistical analysis of real people reacting to unexpected events. We also consider that the emotional state is involved in the modulation of reactions, thus we integrate a model of emotion update. Secondly, we present a semantic-based methodology to compose reactive animation sequences using inverse kinematics (IK) and key frame (KF) interpolation animation techniques. Finally, we present an application that demonstrates how Virtual Humans can produce diferent movements as reaction to unexpected stimuli, depending on their personality traits and emotional state

Animating reactive motion using momentum-based inverse kinematics

Interactive generation of reactive motions for virtual humans as they are hit, pushed and pulled are very important to many applications, such as computer games. In this paper, we propose a new method to simulate reactive motions during arbitrary bipedal activities, such as standing, walking or running. It is based on momentum based inverse kinematics and motion blending. When generating the animation, the user first imports the primary motion to which the perturbation is to be applied to. According to the condition of the impact, the system selects a reactive motion from the database of pre-captured stepping and reactive motions. It then blends the selected motion into the primary motion using momentum-based inverse kinematics. Since the reactive motions can be edited in real-time, the criteria for motion search can be much relaxed than previous methods, and therefore, the computational cost for motion search can be reduced. Using our method, it is possible to generate reactive motions by applying external perturbations to the characters at arbitrary moment while they are performing some actions

Semantics for virtual humans

Population of Virtual Worlds with Virtual Humans is increasing rapidly by people who want to create a virtual life parallel to the real one (i.e. Second Life). The evolution of technology is smoothly providing the necessary elements to increase realism within these virtual worlds by creating believable Virtual Humans. However, creating the amount of resources needed to succeed this believability is a difficult task, mainly because of the complexity of the creation process of Virtual Humans. Even though there are many existing available resources, their reusability is difficult because there is not enough information provided to evaluate if a model contains the desired characteristics to be reused. Additionally, the knowledge involved in the creation of Virtual Humans is not well known, nor well disseminated. There are several different creation techniques, different software components, and several processes to carry out before having a Virtual Human capable of populating a virtual environment. The creation of Virtual Humans involves: a geometrical representation with an internal control structure, the motion synthesis with different animation techniques, higher level controllers and descriptors to simulate human-like behavior such individuality, cognition, interaction capabilities, etc. All these processes require the expertise from different fields of knowledge such as mathematics, artificial intelligence, computer graphics, design, etc. Furthermore, there is neither common framework nor common understanding of how elements involved in the creation, development, and interaction of Virtual Humans features are done. Therefore, there is a need for describing (1) existing resources, (2) Virtual Human's composition and features, (3) a creation pipeline and (4) the different levels/fields of knowledge comprehended. This thesis presents an explicit representation of the Virtual Humans and their features to provide a conceptual framework that will interest to all people involved in the creation and development of these characters. This dissertation focuses in a semantic description of Virtual Humans. The creation of a semantic description involves gathering related knowledge, agreement among experts in the definition of concepts, validation of the ontology design, etc. In this dissertation all these procedures are presented, and an Ontology for Virtual Humans is described in detail together with the validations that conducted to the resulted ontology. The goal of creating such ontology is to promote reusability of existing resources; to create a shared knowledge of the creation and composition of Virtual Humans; and to support new research of the fields involved in the development of believable Virtual Humans and virtual environments. Finally, this thesis presents several developments that aim to demonstrate the ontology usability and reusability. These developments serve particularly to support the research on specialized knowledge of Virtual Humans, the population of virtual environments, and improve the believability of these characters

Simulation de mouvement humain sur postes de travail pour le diagnostic et l'aide à la conception

Les travaux présentés dans ce mémoire concernent la génération automatique de postures et mouvements humains sur poste de travail industriel. L'objectif poursuivi est d'animer de façon réaliste un mannequin numérique afin de simuler un opérateur dans l'exécution de sa tâche. Cette animation doit permettre d'aider à l'analyse des facteurs biomécaniques pouvant engendrer des Troubles Musculo-Squelettiques. Dans un premier temps, des choix de modélisation sont proposés en fonction de ce contexte spécifique. Le modèle retenu se base sur une représentation squelettique du haut du corps composé de corps rigides et de liaisons idéales et intègre des données anthropométriques. Ensuite, un schéma général de lois de commande à base de modèle cinématique est développé. Il est décliné en plusieurs stratégies qui sont testées sur des mouvements caractéristiques et sur poste de travail. Ces tests et la comparaison aux mesures effectuées sur sujet humain permettent d'évaluer les performances du schéma de commande et les choix réalisés. Ces travaux ont donné naissance à un outil logiciel, baptisé OLARGE-TMS, de simulation de mouvement humain sur poste de travail. ABSTRACT : The works presented in this memory concern the automatic generation of postures and human movements on industrial workstation. The aim is to animate in a realistic way a numerical mannequin in order to simulate an operator in the execution of his task. This animation must make it possible to contribute to the analysis of the biomechanical factors which can engender musculo-skeletal disorders. At first, choices of modelling are proposed according to this specific context. The model selected is based on a skeletal representation of the top of the body made up of rigid bodies and ideal connections, and integrates anthropometric data. Then, a general plan of laws of order based on kinematic model is developed. It is declined in several strategies which are tested on characteristic movements and workstation. These tests and the comparison with the measurements taken on human subject make it possible to evaluate the performances of the plan of order and the choices carried out. This work gave rise to a software tool, baptized OLARGE-TMS, for simulation of human movement on workstatio

Motion Capture and Retrieval Animating reactive motion using momentum-based inverse kinematics

Interactive generation of reactive motions for virtual humans as they are hit, pushed and pulled are very important to many applications, such as computer games. In this paper, we propose a new method to simulate reactive motions during arbitrary bipedal activities, such as standing, walking or running. It is based on momentum based inverse kinematics and motion blending. When generating the animation, the user first imports the primary motion to which the perturbation is to be applied to. According to the condition of the impact, the system selects a reactive motion from the database of pre-captured stepping and reactive motions. It then blends the selected motion into the primary motion using momentum-based inverse kinematics. Since the reactive motions can be edited in real-time, the criteria for motion search can be much relaxed than previous methods, and therefore, the computational cost for motion search can be reduced. Using our method, it is possible to generate reactive motions by applying external perturbations to the characters at arbitrary moment while they are performing some actions. Copyright # 2005 John Wiley & Sons, Ltd. KEY WORDS: computer animation; inverse kinematics; real-time animatio