Michael Gervautz

The studierstube augmented reality project

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 computingto the interface as needed. The environment is controlled by the Personal Interaction Panel, a twohanded, pen-and-pad interface that has versatile uses for interacting with the virtual environment. Studierstube also borrows elements from the desktop, such as multitasking 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.

A simple method for color quantization: octree quantization

A new method for filling a color table is presented that produces pictures of similar quality as existing methods, but requires less memory and execution time. All colors of an image are inserted in an octree, and this octree is reduced from the leaves to the root in such a way that every pixel has a well defined maximum error. The algorithm is described in PASCAL notation.

The Personal Interaction Panel – a Two-Handed Interface for Augmented Reality

This paper describes the introduction of a new interaction paradigm to augmented reality applications. The everyday tool handling experience of working with pen and notebooks is extended to create a three dimensional two‐handed interface, that supports easy‐to‐understand manipulation tasks in augmented and virtual environments. In the design step we take advantage from the freedom, given by our very low demands on hardware and augment form and functionality to this device. On the basis of examples from object manipulation, augmented research environments and scientific visualization we show the generality of applicability. Although being in the first stages implementation, we consider the wide spectrum of suitability for different purposes.

Collaborative gaming in augmented reality

We introduce a local collaborative environment for gaming. In our setup multiple users can interact with the virtual game and the real surroundings at the same time. They are able to communicate with other players during the game. We describe an augmented reality setup for multiple users with see-trough head-mounted displays, allowing dedicated stereoscopic views and individualized interaction for each user. We use face-snapping for fast and precise direct object manipulation. With face snapping and the subdivision of the gaming space into spatial regions, the semantics of actions can be derived out of geometric actions of the user. Further, we introduce a layering concept allowing individual views onto the common data structure. The layer concept allows to make privacy management very easy by simply manipulating the common data structure. Moreover, assigning layers to spatial regions carefully, a special privacy management is often not necessary. Moving objects from one region into another will automatically change their visibility and privacy for each participant. We demonstrate our system with two example board-games: Virtual Roulette and MahJongg, both relying heavily on social communication and the need of a private space.

Demand-Driven Geometry Transmission for Distributed Virtual Environments

We present a strategy for rendering in distributed virtual environments. A geometry database is maintained by a server, while users invoke individual clients to interact with the environment. Instead of downloading a complete copy of the geometry data, the data is distributed on demand, thus gaining signifcant savings in network bandwidth. Our strategy combines several techniques, including levels of detail, progressive refinement and graceful degradation to deliver the data “just in time” over the network to the rendering process. The method allows operate on a tight resource budget, which important if attempting to use low cost systems for virtual reality applications.

Occlusion in Collaborative Augmented Environments

Abstract Augmented environments superimpose computer enhancements on the real world. Such augmented environments are well suited for collaboration of multiple users. To improve the quality and consistency of the augmentation the occlusion of real objects by computer-generated objects and vice versa has to be implemented. We present methods how this can be done for a tracked users body and other real objects and how irritating artifacts due to misalignments can be reduced. Our method is based on simulating the occlusion of virtual objects by a representation of the user modeled as kinematic chains of articulated solids. Smoothing the border between virtual world and occluding real reduces registration and modeling errors of this model. Finally, an implementation in our augmented environment and the resulting improvements are presented.

“Studierstube”: An environment for collaboration in augmented reality

We propose an architecture for multi-user augmented reality with applications in visualisation, presentation and education, which we call “Studierstube”. Our system presents three-dimensional stereoscopic graphics simultaneously to a group of users wearing light weight see-through head mounted displays. The displays do not affect natural communication and interaction, making working together very effective. Users see the same spatially aligned model, but can independently control their viewpoint and different layers of the data to be displayed. The setup serves computer supported cooperative work and enhances cooperation of visualisation experts. This paper presents the client-server software architecture underlying this system and details that must be addressed to create a high-quality augmented reality setup.

Anywhere Interfaces Using Handheld Augmented Reality

An investigation of the technology and human factors that drive augmented reality research describes recent developments in handheld AR, concentrating on localization, tracking, interaction, and visualization, and offers several examples illustrating the vast potential and important applications of AR. A related video can be seen here: http://youtu.be/ol371rIyUFY. It shows several real-world examples illustrating the vast potential and important applications of augmented reality.

Collaborative visualization in augmented reality

The authors discuss Studierstube, a low-cost augmented reality system. The system features true stereoscopy, 3D interaction, individual viewpoints and customized views for multiple users, and unhindered natural collaboration.

Modeling and rendering of outdoor scenes for distributed virtual environments

We present an approach for modeling and realtime rendering of outdoor scenes, for use in virtual reality applications such as flight simulators and multi-user virtual environments. The models are based on a procedural representation using directed cyclic graphs. It allows to represent extremely complex scenes with little memory and modeling effort. Very large scale virtual environments are supported by a bandwidth-preserving networking approach that makes use of the compact representation and on-the-fly database amplification.