Adaptive hypermedia is a new direction of research within the area of adaptive and user model-based interfaces. Adaptive hypermedia (AH) systems build a model of the individual user and apply it for adaptation to that user, for example, to adapt the content of a hypermedia page to the user's knowledge and goals, or to suggest the most relevant links to follow. AH systems are used now in several application areas where the hyperspace is reasonably large and where a hypermedia application is expected to be used by individuals with different goals, knowledge and backgrounds. This paper is a review of existing work on adaptive hypermedia. The paper is centered around a set of identified methods and techniques of AH. It introduces several dimensions of classification of AH systems, methods and techniques and describes the most important of them.

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Methods and techniques of adaptive hypermedia

Automatic generation and detection of highly reliable fiducial markers under occlusion

This paper surveys the current state-of-the-art of technology, systems and applications in Augmented Reality. It describes work performed by many different research groups, the purpose behind each new Augmented Reality system, and the difficulties and problems encountered when building some Augmented Reality applications. It surveys mobile augmented reality systems challenges and requirements for successful mobile systems. This paper summarizes the current applications of Augmented Reality and speculates on future applications and where current research will lead Augmented Reality's development. Challenges augmented reality is facing in each of these applications to go from the laboratories to the industry, as well as the future challenges we can forecast are also discussed in this paper. Section 1 gives an introduction to what Augmented Reality is and the motivations for developing this technology. Section 2 discusses Augmented Reality Technologies with computer vision methods, AR devices, interfaces and systems, and visualization tools. The mobile and wireless systems for Augmented Reality are discussed in Section 3. Four classes of current applications that have been explored are described in Section 4. These applications were chosen as they are the most famous type of applications encountered when researching AR apps. The future of augmented reality and the challenges they will be facing are discussed in Section 5.

Augmented reality technologies, systems and applications

One distinctive feature of any adaptive system is the user model that represents essential information about each user This chapter complements other chapters of this book in reviewing user models and user modeling approaches applied in adaptive Web systems The presentation is structured along three dimensions: what is being modeled, how it is modeled, and how the models are maintained After a broad overview of the nature of the information presented in these various user models, the chapter focuses on two groups of approaches to user model representation and maintenance: the overlay approach to user model representation and the uncertainty-based approach to user modeling

User models for adaptive hypermedia and adaptive educational systems

A method of using stereo vision to interface with a computer is provided. The method includes capturing a stereo image, and processing the stereo image to determine position information of an object in the stereo image. The object is controlled by a user. The method also includes communicating the position information to the computer to allow the user to interact with a computer application.

Video-based image control system

Our starting point for developing the Studierstube system was the belief that augmented reality, the less obtrusive cousin of virtual reality, has a better chance of becoming a viable user interface for applications requiring manipulation of complex three-dimensional information as a daily routine. In essence, we are searching for a 3-D user interface metaphor as powerful as the desktop metaphor for 2-D. At the heart of the Studierstube system, collaborative augmented reality is used to embed computer-generated images into the real work environment. In the first part of this paper, we review the user interface of the initial Studierstube system, in particular the implementation of collaborative augmented reality, and the Personal Interaction Panel, a two-handed interface for interaction with the system. In the second part, an extended Studierstube system based on a heterogeneous distributed architecture is presented. This system allows the user to combine multiple approaches-augmented reality, projection displays, and ubiquitous computing--to the interface as needed. The environment is controlled by the Personal Iteraction Panel, a two-handed, pen-and-pad interface that has versatile uses for interacting with the virtual environment. Studierstube also borrows elements from the desktop, such as multi-tasking and multi-windowing. The resulting software architecture is a user interface management system for complex augmented reality applications. The presentation is complemented by selected application examples.

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The studierstube augmented reality project

The Virtual Table presents stereoscopic graphics to a user in a workbench-like setting This paper reports on a user interface and new interaction techniques for the Virtual Table based on transparent props—a tracked hand-held pen and a pad These props, but in particular the pad, are augmented with 3D graphics from the Virtual Table’s display This configuration creates a very powerful and flexible interface for two-handed interaction that can be applied to other back-projected stereographic displays as well: the pad can serve as a palette for tools and controls as well as a window-like see-through interface, a plane-shaped and throughthe-plane tool, supporting a variety of new interaction techniques

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Using transparent props for interaction with the virtual table

The tools include components which are images produced by the system (103) that creates the virtual environment in response to inputs specifying the tool's location and the point of view of the tool's user. One class of the tools includes transparent components (121, 123); the image component of the tool is produced at a location in the virtual environment determined by the transparent component's location and the point of view of the tool's user. Tools in this class include a transparent pad (121) and a transparent stylus (123). The transparent pad (121) has an image component that may be used as a palette, as a magic lens, and as a device for selecting and transporting components of the virtual environment or even a portion of the virtual environment itself.

Tools for interacting with virtual environments

A prototype of an optical extension for table-like rear-projection systems is described. A large, half-silvered mirror beam splitter is used as the optical combiner to unify a virtual and a real workbench. The virtual workbench has been enabled to display computer graphics beyond its projection boundaries and to combine virtual environments with the adjacent real world. A variety of techniques are described and referred to that allow indirect interaction with virtual objects through the mirror. Furthermore, the optical distortion that is caused by the half-silvered mirror combiner is analyzed, and techniques are presented to compensate for this distortion.

L. Miguel Encarnação

Papers

The studierstube augmented reality project

Using transparent props for interaction with the virtual table

Tools for interacting with virtual environments

The Extended Virtual Table: An Optical Extension for Table-Like Projection Systems

A multi-layered architecture for sketch-based interaction within virtual environments