Freeform digital ink annotation allows readers to interact with documents in an intuitive and familiar manner. Such marks are easy to manage on static documents, and provide a familiar annotation experience. In this paper, we describe an implementation of a freeform annotation system that accommodates dynamic document layout. The algorithm preserves the correct position of annotations when documents are viewed with different fonts or font sizes, with different aspect ratios, or on different devices. We explore a range of heuristics and algorithms required to handle common types of annotation, and conclude with a discussion of possible extensions to handle special kinds of annotations and changes to documents.

This work presents constructs called interactive space-time maps along with an application called the SpaceTime Browser for visualizing and retrieving documents. A 3D visualization with 2D planar maps and a time line is employed. Users can select regions on the maps and choose precise time intervals by sliding the maps along the telescopic time line. Regions are highlighted to indicate the presence of documents with matching space-time attributes, and documents are retrieved and displayed in an adjoining workspace. We provide two examples: (1) organizing travel photos, (2) managing documents created by room location-aware devices in a building.

This paper describes how the changing information about an individual's location, environment, and social situation can be used to initiate and facilitate people's interactions with one another, individually and in groups. Context-aware communication is contrasted with other forms of context-aware computing and we characterize applications in terms of design decisions along two dimensions: the extent of autonomy in context sensing and the extent of autonomy in communication action. A number of context-aware communication applications from the research literature are presented in five application categories. Finally, a number of issues related to the design of context-aware communication applications are presented.

Squeezing desktop Web content into smart phones and text pagers is more practical with separate interfaces for navigation and content manipulation. m-Links, a middleware proxy system, supports this dual-mode browsing, offering phonetop users an extendable set of actions.

We present methods for automatically producing summary excerpts or thumbnails of music. To find the most representative excerpt, we maximize the average segment similarity to the entire work. After window-based audio parameterization, a quantitative similarity measure is calculated between every pair of windows, and the results are embedded in a 2-D similarity matrix. Summing the similarity matrix over the support of a segment results in a measure of how similar that segment is to the whole. This measure is maximized to find the segment that best represents the entire work. We discuss variations on the method, and present experimental results for orchestral music, popular songs, and jazz. These results demonstrate that the method finds significantly representative excerpts, using very few assumptions about the source audio.

We present a method for characterizing both the rhythm and tempo of music. We also present ways to quantitatively measure the rhythmic similarity between two or more works of music. This allows rhythmically similar works to be retrieved from a large collection. A related application is to sequence music by rhythmic similarity, thus providing an automatic "disc jockey" function for musical libraries. Besides specific analysis and retrieval methods, we present small-scale experiments that demonstrate ranking and retrieving musical audio by rhythmic similarity.

As ubiquitous computing becomes widespread, we are increasingly coming into contact with "shared" computer-enhanced devices, such as cars, televisions, and photocopiers. Our interest is in identifying general issues in personalizing such shared everyday devices. Our approach is to compare alternative personalization methods by deploying and using alternative personalization interfaces (portable and embedded) for three shared devices in our workplace (a presentation PC, a plasma display for brainstorming, and a multi-function copier). This paper presents the comparative prototyping methodology we employed, the experimental system we deployed, observations and feedback from use, and resulting issues in designing personalized shared ubiquitous devices.

Evaluating ubiquitous systems is hard, and has attracted the attention of others in the research community. These investigators, like others in CSCW, argue there is a basic mismatch between traditional evaluation techniques and the needs posed by ubiquitous systems. Namely, these systems are embedded in a variety of complex real world environments that cannot be easily modeled (as required by theoretical analyses), simulated, measured, or controlled (as required by laboratory experiments). As a result, many investigators have abandoned traditional comparative evaluation techniques and opted instead for techniques adapted from the social sciences, such as anthropology. We wanted to perform a comparative evaluation similar to a laboratory experiment, but in such a way that we could observe the effects of our design decisions in relatively unconstrained, real world use. This led us to the process described in this paper.

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.