The TactGuide is a mobile navigation device 'displaying' personalized direction cues by means of a tactile and 'tactful' representation. The TactGuide is operated by tactile inspection which is subtle enough to allow the users to engage/disengage in device interaction while preserving their visual, auditory and kinesthetic senses for inspection of the environment. The TactGuide design thereby accommodates the users' need to economize their attentional resources between device and environment while navigating through physical space. Preliminary experiments indicates that users readily map the tactile cues to spatial directions and that TactGuide can be operated as a supplement to, and without compromising, the use of our existing wayfinding abilities. substituting the use of our natural abilities and earned skills for wayfinding.

To implement any quantum operation (a.k.a. ``superoperator'' or ``CP map'') on a d-dimensional quantum system, it is enough to apply a suitable overall unitary transformation to the system and a d^2-dimensional environment which is initialized in a fixed pure state. It has been suggested that a d-dimensional environment might be enough if we could initialize the environment in a mixed state of our choosing. In this note we show with elementary means that certain explicit quantum operations cannot be realized in this way. Our counterexamples map some pure states to pure states, giving strong and easily manageable conditions on the overall unitary transformation. Everything works in the more general setting of quantum operations from d-dimensional to d'-dimensional spaces, so we place our counterexamples within this more general framework.

This volume is the edited proceedings of the ACM conference on Collabroative Virtual Environments.

We present a method for rapidly and robustly extracting audio excerpts without the overhead of speech recognition or speaker segmentation. An immediate application is to automatically augment keyframe-based video summaries with informative audio excerpts associated with the video segments represented by the keyframes. Short audio clips combined with keyframes comprise an extremely lightweight and Web-browsable interface for auditioning video or similar media, without using bandwidth-intensive streaming video or audio.

This paper presents a camera system called FlySPEC. In contrast to a traditional camera system that provides the same video stream to every user, FlySPEC can simultaneously serve different video-viewing requests. This flexibility allows users to conveniently participate in a seminar or meeting at their own pace. Meanwhile, the FlySPEC system provides a seamless blend of manual control and automation. With this control mix, users can easily make tradeoffs between video capture effort and video quality. The FlySPEC camera is constructed by installing a set of Pan/Tilt/Zoom (PTZ) cameras near a high-resolution panoramic camera. While the panoramic camera provides the basic functionality of serving different viewing requests, the PTZ camera is managed by our algorithm to improve the overall video quality that may affect users watching details. The video resolution improvements from using different camera management strategies are compared in the experimental section.

Given panoramic video taken along a self-intersecting path, we present a method for detecting the intersection points. This allows "virtual tours" to be synthesized by splicing the panoramic video at the intersection points. Spatial intersections are detected by finding the best-matching panoramic images from a number of nearby candidates. Each panoramic image is segmented into horizontal strips. Each strip is averaged in the vertical direction. The Fourier coefficients of the resulting 1-D data capture the rotation-invariant horizontal texture of each panoramic image. The distance between two panoramic images is calculated as the sum of the distances between their strip texture pairs at the same row positions. The intersection is chosen as the two candidate panoramic images that have the minimum distance.

We present a framework, motivated by rate-distortion theory and the human visual system, for optimally representing the real world given limited video resolution. To provide users with high fidelity views, we built a hybrid video camera system that combines a fixed wide-field panoramic camera with a controllable pan/tilt/zoom (PTZ) camera. In our framework, a video frame is viewed as a limited-frequency representation of some "true" image function. Our system combines outputs from both cameras to construct the highest fidelity views possible, and controls the PTZ camera to maximize information gain available from higher spatial frequencies. In operation, each remote viewer is presented with a small panoramic view of the entire scene, and a larger close-up view of a selected region. Users may select a region by marking the panoramic view. The system operates the PTZ camera to best satisfy requests from multiple users. When no regions are selected, the system automatically operates the PTZ camera to minimize predicted video distortion. High-resolution images are cached and sent if a previously recorded region has not changed and the PTZ camera is pointed elsewhere. We present experiments demonstrating that the panoramic image can effectively predict where to gain the most information, and also that the system provides better images to multiple users than conventional camera systems.

As the technology for communication changes, the role of communication in the conduct of business changes with it. Communication is no longer just a technical matter of separating signal from noise and managing bandwidth but also a social matter in which negotiating differences in understanding among and between communicators is a primary business priority. Addressing this priority requires an understanding of how individuals interact in the course of their decision making activities. Using the work of Anthony Giddens as a point of departure, this paper views interaction in communication as consisting of three dimensions - meaning, authority, and trust. These three dimensions are used to identify new opportunities for advances in decision making technology which help deal with potential breakdowns in social interaction.

A basic objective of Weiser's Ubiquitous Computing vision is ubiquitous information access: being able to utilize any content or service (e.g., all the rich media content and services on the WWW), using devices that are always "at hand" (embedded in environments or portable), over a network with universal coverage and adequate bandwidth. Although much progress has been made, the ideal remains elusive. This paper examines the inter-relations among three dimensions of ubiquitous information systems: (1) ubiquitous content; (2) ubiquitous devices; and (3) ubiquitous networking. We use the space defined by these dimensions to reflect on the tradeoffs designers make and to chart some past and current information systems. Given this background, we present m-Links (mobile links), a new system that takes aim at the elusive ideal of ubiquitous information. Our approach builds on wireless web phone technologies because of their trend towards ubiquitous devices and networking (the second and third dimensions). Yet such very small devices sacrifice usability as rich media Internet terminals (the first dimension). To offset this limitation, we propose a new information access model for very small devices that supports a much wider range of content and services than previously possible. We have built this system with an emphasis on open systems extensibility and describe its design and implementation.

Hypertext interfaces typically involve navigation, the act (and interaction) of moving from one piece of information to another. Navigation can be exploratory, or it may involve backtracking to some previously-visited node. While backtracking interfaces are common, they may not reflect differences in readers' purposes and mental models. This paper draws on some empirical evidence regarding navigation between and within documents to suggest improvements on traditional hypertext navigation, and proposes a time-based view of backtracking.

In the emerging world of electronic publishing how we create, distribute, and read books will be in a large part determined by an underlying framework of content standards that establishes the range of technological opportunities and constraints for publishing and reading systems. But efforts to develop content standards based on sound engineering models must skillfully negotiate competing and sometimes apparently irreconcilable objectives if they are to produce results relevant to the rapidly changing course of technology. The Open eBook Forum's Publication Structure, an XML-based specification for electronic books, is an example of the sort of timely and innovative problem solving required for successful real-world standards development. As a result of this effort, the electronic book industry will not only happen sooner and on a larger scale than it would have otherwise, but the electronic books it produces will be more functional, more interoperable, and more accessible to all readers. Public interest participants have a critical role in this process.

S. Vassilvitskii, J. Kubica, E. G. Rieffel, J. W. Suh, M. Yim

Shared text input is a technique we implemented into a note taking system for facilitating text entry on small devices. Instead of writing out words on the tedious text entry interfaces found on handheld computers, users can quickly reuse words and phrases already entered by others. Sharing notes during a meeting also increases awareness among note takers. We found that filtering the text to share was appropriate to deal with a variety of design issues such as screen real estate, scalability, privacy, reciprocity, and predictability of text location

In this paper, we describe an evaluation of the Palette, a presentation tool that was reported at CHI '99. The Palette allows presenters to quickly access digital presentations using physical cards that have unique barcodes printed on them. The Palette has been in use in our lab for over three years, and has been released as a product in Japan. Our evaluation consists of an analysis of usage logs, an expert walkthrough review, and observations and interviews with users, non-users and the system administrator. The findings reveal benefits and drawbacks of the technology, and offers design ideas for further work on tangible tools of this kind.

We describe our experiences with the design, implementation, deployment, and evaluation of a Portholes tool which provides group and collaboration awareness through the Web. The research objective was to explore how such a system would improve communication and facilitate a shared understanding among distributed development groups. During the deployment of our Portholes system, we conducted a naturalistic study by soliciting user feedback and evolving the system in response. Many of the initial reactions of potential users indicated that our system projected the wrong image so that we designed a new version that provided explicit cues about being in public and who is looking back to suggest a social rather than information interface. We implemented the new design as a Java applet and evaluated design choices with a preference study. Our experiences with different Portholes versions and user reactions to them provide insights for designing awareness tools beyond Portholes systems. Our approach is for the studies to guide and to provide feedback for the design and technical development of our system.

In this paper, we document an extension to traditional pattern-theoretic object templates to jointly accommodate variations in object pose and in the radiant appearance of the object surface. We first review classical object templates accommodating pose variation. We then develop an efficient subspace representation for the object radiance indexed on the surface of the three dimensional object template. We integrate the low-dimensional representation for the object radiance, or signature, into the pattern-theoretic template, and present the results of orientation estimation experiments. The experiments demonstrate both estimation performance fluctuations under varying illumination conditions and performance degradations associated with unknown scene illumination. We also present a Bayesian approach for estimation accommodating illumination variability.

The increasing number of wireless, portable devices has led inevitably to lyrical rhetorics of business cost-cutting and increased efficiency as workers can be productive while on the and offices become streamlined areas of efficient activity. In this short paper, we raise a number if issues that have been appearing in common discourses the (most) modern office, and the impact of wireless technologies thereupon. We also present an overview of a workshop held at ECSCW in Bonn in September of 2001 on this topic, giving an overview of the comments and discussions that took place at the workshop.

Recent years have seen a marked increase in the production and promotion of portable, wireless communication devices: mobile phones with internet access, wireless PDAs such as the Palm VII and smart pagers such as RIM's 850 and 950. Some claim the presence of such devices in the hands, bags and pockets of so many people heralds a new world of work in which people can be reached and information accessed "anywhere, anytime". Whether or not access to information in itself can promote new working practices, individuals whose lives revolve around movement between work sites have been singled out as an obvious market for such portable wireless communication devices. Using these devices such “mobile workers” can be in touch with colleagues, collaborators and clients "24/7", and still sustain non-work social relationships due, apparently, to their constant connectedness whilst mobile. In this chapter we have two goals. The first is to address the design of mobile technologies. This second is to illustrate our design approach, wherein we consider local practices of technology use, but also the broader cultural context in which technologies are designed, produced, bought, sold, used and redesigned. Our ultimate design aim is to build upon existing practices, but also to consider possibilities for the development of innovative technologies that enable new, complementary, practices.

In this paper, we present a novel framework for analyzing video using self-similarity. Video scenes are located by analyzing inter-frame similarity matrices. The approach is flexible to the choice of similarity measure and is robust and data-independent because the data is used to model itself. We present the approach and its application to scene boundary detection. This is shown to dramatically outperform a conventional scene-boundary detector that uses a histogram-based measure of frame difference.