Semantics for Virtual Humans

Autor: Alejandra Garcia Rojas Martinez
Local: Escola Politécnica Federal de Lausanne, Suiça
Orientadores: Profs. D. Thalmann
Ano: 2009

Abstract:

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.

Semantic Virtual Environments

Autor: Mario A. Gutiérrez Alonso
Local: Escola Politécnica Federal de Lausanne, Suiça
Orientadores: Profs. D. Thalmann & F. Vexo
Ano: 2005

Abstract:

The main problem targeted by this research is the lack of flexibility of virtual objects within a Virtual Environment. Virtual objects are diffcult to re-use in applications or contexts different from the ones they were designed for. This refers mainly to the need for adaptive entities, from the points of view of the geometric representation and user interface. The solution we propose is based on a semantic model aimed at representing the meaning, and functionality of objects in a virtual scene; including their geometric representation and user interface.

This thesis is divided into four main parts. First we define a semantic model for Virtual Environments populated by digital items (virtual entities). Then we focus on three main aspects of the development and use of Virtual Environments: interaction, visualization and animation. We describe the needs and benefits of using a semantics-based representation for: animating virtual characters; interacting within Virtual Environments and visualizing them in different contexts/devices (handhelds, hi-resolution displays, text-based devices, etc.).

The thesis concludes by exploring a novel trend in research that builds upon knowledge-base technologies and the emerging Semantic Web initiatives: the use of ontologies for Virtual Environments. A preliminary version of an ontology for Virtual Humans is presented. When using ontologies, digital entities can be understood by both humans and machines and be reused in a wide range of contexts and applications. Semantic Virtual Environments are composed of such reusable and adaptive digital items.