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Über dieses Buch

The book describes recent research results in the areas of modelling, creation, management and presentation of interactive 3D multimedia content. The book describes the current state of the art in the field and identifies the most important research and design issues. Consecutive chapters address these issues. These are: database modelling of 3D content, security in 3D environments, describing interactivity of content, searching content, visualization of search results, modelling mixed reality content, and efficient creation of interactive 3D content. Each chapter is illustrated with example applications based on the proposed approach. The final chapter discusses some important ethical issues related to the widespread use of virtual environments in everyday life. The book provides ready to use solutions for many important problems related to the creation of interactive 3D multimedia applications and will be a primary reading for researchers and developers working in this domain.



Chapter 1. Introduction

Progress in computing and network performance, accompanied by development of platform independent 3D content standards, opens the way for application of interactive 3D technologies in a variety of domains such as cultural heritage, education, training, tourism, and e-commerce. However, the potential of 3D/VR/AR technologies in everyday applications can be fully exploited only if complemented by the development of efficient and easy-to-use methods of creation, management, search, and presentation of interactive 3D multimedia content, which could be used by both expert and non-expert users. The whole book is devoted to the above issues. In this introductory chapter, we describe motivation for conducting research in the domain of interactive 3D multimedia content technologies, which focuses on two broad areas: 3D content creation and management, and 3D search and presentation. Then, a detailed description of chapters composing this book is provided.
Wojciech Cellary, Krzysztof Walczak

Chapter 2. Interactive 3D Content Standards

Development of 3D interactive network applications requires standards for representing 3D content as well as metadata standards for describing the content. In this chapter, selected standards for content representation and content description are presented. In particular, the VRML, X3D, and MPEG-4 ISO/IEC standards are presented. Other standards such as U3D, COLLADA, and 3D XML are also discussed and compared. Metadata standards suitable for describing interactive 3D content are also presented.
Wojciech Cellary, Krzysztof Walczak

Chapter 3. Issues in Creation, Management, Search and Presentation of Interactive 3D Content

In this chapter, the main issues and challenges related to creation, management, search and presentation of interactive 3D content are presented. The challenges result mainly from the continuous progress in development of 3D/VR technologies and systems. In particular, the following shifts are presented: from passive 3D content to active 3D applications, from 3D geometry to meaningful interactive virtual environments, from single-user to multi-user 3D content creation, from file search to 3D object search, and from 3D scenes to efficient 3D visualization interfaces.
Wojciech Cellary, Krzysztof Walczak

Chapter 4. Dynamic Database Modeling of 3D Multimedia Content

In this chapter, a new approach that enables building active 3D/VR applications, called X-VR, is presented. The term “active” is used to describe applications that enable server-side user interaction, dynamic composition of virtual scenes, access to on-line data, selection of content, alternative visualizations, personalization, and implementation of persistency. In the X-VR approach, two new techniques are used: dynamic content modeling, which provides the prerequisite infrastructure for building active 3D/VR applications, and database modeling of virtual worlds, which enables building high-level database models of 3D virtual environments. Dynamic content modeling is accomplished by the use of the X-VRML language. X-VRML is a new high-level XML-based language that extends 3D content standards allowing convenient access to databases, object-orientation, parameterization, and imperative programming techniques. For database modeling of virtual worlds, a model called X-VRDB is proposed. In this model, a virtual world is conceptually divided into several distinct elements that are separately represented in a database. These two techniques constitute the main building blocks of advanced interactive 3D/VR applications.
Krzysztof Walczak

Chapter 5. Building Configurable 3D Web Applications with Flex-VR

In this chapter, a novel approach to building behavior-rich interactive 3D Web applications is presented. The approach, called Flex-VR, enables building configurable 3D applications in which content can be relatively easily created and modified by common users. Flex-VR applications are based on configurable content, i.e., content that may be interactively or automatically configured based on a library of components. Configuration of application content from components simplifies content creation allowing users without programming skills to perform this task efficiently. Experienced users—programmers and 3D designers—can add new components to the library, thus extending system capabilities. In this chapter, an overview of the Flex-VR approach is provided and two important elements of the Flex-VR are described in detail: Flex-VR content structuralization and Flex-VR content model. A number of design patterns, which enable configuration of complex content structures, and an example Flex-VR application are also presented.
Krzysztof Walczak

Chapter 6. Modeling Interactive Augmented Reality Environments

In this chapter, an approach to creation of augmented reality environments, called Augmented Reality Environment Modeling (AREM), is presented. The concept of augmented reality is explained and the components of augmented reality environments are presented. In the AREM approach, augmented reality environments are created based on Augmented Reality Scene Model (ARSM), which defines the concepts of AR-Class and AR-Object following the object-oriented paradigm. The object-oriented concept of a class composed of properties and methods is enhanced with elements required for building interactive augmented reality environments: geometry, interactive behavior, media objects, dependences between properties, and aggregation relationships. The geometry and behavior specified in AR-Classes can be parameterized using their properties and relationships. Thus, content creators are able to alter the geometry and behavior of AR-Objects by setting the property values and the relationships with other AR-Objects. Visual and behavioral characteristics of AR-Objects can be dynamically changed over time due to the changes applied to the property values of these AR-Objects. The chapter is concluded with a presentation of the application of the AREM approach to building augmented reality learning environments, which enable learners to directly interact with the learning content presented in their real environment.
Rafał Wojciechowski

Chapter 7. Secure User-Contributed 3D Virtual Environments

This chapter deals with the problem of access control in 3D virtual environments which are interactive, behavior-rich, multi-user, and based on user-contributed content. Traditional coarse-grained and geometry-centric privilege modeling methods are not sufficient for such environments. New methods are required that concern not only geometrical models, their relationships and structure, but also inter-object behavioral interactions. In this chapter, a method called Selective Semantic Modeling (SSM) is described. The SSM method enables modeling of privileges for behavioral objects with respect to their semantics. The SSM method is based on the concept of semantic operations, which are generated at run-time from the current content structure of a virtual environment and are applicable to the access control model as a part of a privilege. Semantic consistency of the privilege is guaranteed by a two-phase regeneration and validation mechanism, so that user privileges can be expressed in a precise, semantically accurate and flexible way.
Adam Wójtowicz

Chapter 8. Describing Interactivity of 3D Content

Effective search for interactive 3D objects needed for new applications requires object metadata that cover not only object geometry and semantics, but also behavior. Existing metadata standards define different information describing an object. The missing metadata fragment, not included in existing metadata standards, is metadata of object behavior. Such information should be stored in a format which enables efficient search for objects with specific interaction properties. In this chapter, a new approach to describe interactivity of 3D objects is presented, in which the object behavior is described by models of potential object interactions with other objects. The proposed approach is based on two main elements: a model of interactive object interactions and a concept of interaction interface. The model of object interactions decomposes an interaction into Event, Condition and Action components described by distinct metadata structures that use textual semantic descriptions and formal mathematical descriptions. The interaction interface concept enables definition and sharing of detailed semantics of parameters related with interactions. The solution was implemented as metadata schemas in a form of XML Schemas.
Jacek Chmielewski

Chapter 9. Searching Content Related by Semantics, Space and Time

In many practical search applications, information resources that are processed are described by their semantic, spatial, and temporal relations to other resources. Sometimes their meaning is different, depending on the place and time or even the resources change in time and place. Existing search methods are insufficient for such data because they do not take into consideration all the three aspects together.
In this chapter, a new search method of the information resources described by semantic relations and spatiotemporal properties, called TSTSM (Theme-Space-Time Search Method), is described. The TSTSM is based on the TST similarity measure that allows assessing the distance between different concepts in a semantic, spatiotemporal dataset. The main features of the TSTSM method include its ability to seamlessly deal with concepts evolving in space and time, to operate on both imprecise data and imprecisely defined user queries, to rank the search results, and to provide extensive visualizations of the result sets. Precision and recall of the TSTSM have been evaluated in comparison with keyword and relation based search engines.
Mirosław Stawniak

Chapter 10. Interactive 3D Visualization of Search Results

With a growing number of Web documents, the question of information availability and discovery is still open, even considering the rising power of search engines. One of promising methods permitting Internet users to find desired information is creation of visualization interfaces that enable an overview of the entire search result enabling fast identification of appropriate documents. In this chapter, we present a novel method, called AVE—Adaptive Visualization Environment that supports users in document retrieval process through search result visualization in a dynamically selected and parameterized interface which best corresponds to properties of the search result. The interface is selected automatically based on applied readability prerequisites. In this chapter, a prototype Periscope system implementing the AVE method is also presented.
Wojciech Wiza


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