Systems that detect the unaugmented human body allow players to interact without using a physical controller. But how is interaction altered by the absence of a physical input device? What is the impact on game performance, on a player's expectation of their ability to control the game, and on their game experience? In this study, we investigate these issues in the context of a table tennis video game. The results show that the impact of holding a physical controller, or indeed of the fidelity of that controller, does not appear in simple measures of performance. Rather, the difference between controllers is a function of the responsiveness of the game being controlled, as well as other factors to do with expectations, real world game experience and social context.

In this paper we elucidate the patterns of behavior of home movie makers through a study of 12 families and a separate focus group of 7 teenagers. Analogous to a similar study of photowork [13], the goal is to provide a deeper understanding of what people currently do with video technologies, balancing the preponderence of techno-centric work in the area with appropriate user-centric insight. From our analysis, we derive a videowork lifecycle to frame the practices users engage in when working with video technologies in the home, and uncover two broad types of video usage therein. This has implications for how we conceive of and devise tools to support these practices, as we discuss.

We report on the results of a study using SenseCam, a "life-logging" technology in the form of a wearable camera, which aims to capture data about everyday life in order to support people's memory for past, personal events. We find evidence that SenseCam images do facilitate people's ability to connect to their past, but that images do this in different ways. We make a distinction between "remembering" the past, and "knowing" about it, and provide evidence that SenseCam images work differently over time in these capacities. We also compare the efficacy of user-captured images with automatically captured images and discuss the implications of these findings and others for how we conceive of and make claims about life-logging technologies.

We demonstrate a fully working system for multifaceted browsing over large collections of text-annotated data, such as annotated images, that are stored in relational databases. Typically, such databases can be browsed across multiple facets (by topic, genre, location, and so on) and previous user studies showed that multifaceted interfaces improve substantially the ability of users to identify items of interest in the database. We demonstrate a scalable system that automatically generates multifaceted browsing hierarchies on top of a relational database that stores the underlying text-annotated objects. Our system supports a wide range of ranking alternatives for selecting and displaying the best facets and the best portions of the generated hierarchies, to facilitate browsing. We combine our ranking schemes with Rapid Serial Visual Presentation (RSVP), an advanced visualization technique, which further enhances the browsing experience and demonstrate how to use prefetching techniques to overcome the latency issues that are inherent when browsing the contents of a relational database using multifaceted interfaces.

We present a system for the peripheral display of digital handwritten notes, motivated by the joint observation that people seldom refer back to their notes and that these notes often contain useful information. We describe the user-led design of the system, incorporating interviews, paper prototypes, and interactive prototypes. A preliminary field trial of the system indicates that users derive value from the system both for low-distraction reminding and for serendipitous idea generation. These promising initial results suggest significant scope for future work.

In this paper we introduce the notion of "photowork" as the activities people perform with their digital photos after cap-ture but prior to end use such as sharing. Surprisingly, these processes of reviewing, downloading, organizing, editing, sorting and filing have received little attention in the litera-ture yet they form the context for a large amount of the 'search' and 'browse' activities so commonly referred to in studies of digital photo software. Through a deeper under-standing of photowork using field observation and inter-views, we seek to highlight its significance as an interaction practice. At the same time, we discover how "search" as it is usually defined may have much less relevance than new ways of browsing for the design of new digital photo tools, in particular, browsing in support of the photowork activi-ties we describe.

In this paper we describe a field trial designed to investigate the potential of remote, situated messaging within the home. Five households used our "HomeNote" device for approximately a month. The results show a diversity of types of communication which highlight the role of messaging both to a household and to a place. It also shows the ways in which these kinds of messages enable subtle ways of requesting action, expressing affection, and marking identity in a household -- communication types which have received little attention in the research literature. These in turn point to new concepts for technology which we describe.

There is a growing interest in estimating the effectiveness of search. Two approaches are typically considered: examining the search queries and examining the retrieved document sets. In this paper, we take the latter approach. We use four measures to characterize the retrieved document sets and estimate the quality of search. These measures are (i) the clustering tendency as measured by the Cox-Lewis statistic, (ii) the sensitivity to document perturbation, (iii) the sensitivity to query perturbation and (iv) the local intrinsic dimensionality. We present experimental results for the task of ranking 200 queries according to the search effectiveness over the TREC (discs 4 and 5) dataset. Our ranking of queries is compared with the ranking based on the average precision using the Kendall t statistic. The best individual estimator is the sensitivity to document perturbation and yields Kendall t of 0.521. When combined with the clustering tendency based on the Cox-Lewis statistic and the query perturbation measure, it results in Kendall t of 0.562 which to our knowledge is the highest correlation with the average precision reported to date.

Databases of text and text-annotated data constitute a significant fraction of the information available in electronic form. Searching and browsing are the typical ways that users locate items of interest in such databases. Interfaces that use multifaceted hierarchies represent a new powerful browsing paradigm which has been proven to be a successful complement to keyword searching. Thus far, multifaceted hierarchies have been created manually or semi-automatically, making it difficult to deploy multifaceted interfaces over a large number of databases. We present automatic and scalable methods for creation of multifaceted interfaces. Our methods are integrated with traditional relational databases and can scale well for large databases. Furthermore, we present methods for selecting the best portions of the generated hierarchies when the screen space is not sufficient for displaying all the hierarchy at once. We apply our technique to a range of large data sets, including annotated images, television programming schedules, and web pages. The results are promising and suggest directions for future research.

The growth of digital information increases the need to build better techniques for automatically storing, organizing and retrieving it. Much of this information is textual in nature and existing representation models struggle to deal with the high dimensionality of the resulting feature space. Techniques like latent semantic indexing address, to some degree, the problem of high dimensionality in information retrieval. However, promising alternatives, like random mapping (RM), have yet to be completely studied in this context. In this paper, we show that despite the attention RM has received in other applications, in the case of text retrieval it is outperformed not only by principal component analysis (PCA) and independent component analysis (ICA) but also by a simple noise reduction algorithm.

In this paper we present and discuss the findings of a study that investigated how people manage their collections of digital photographs. The six-month, 13-participant study included interviews, questionnaires, and analysis of usage statistics gathered from an instrumented digital photograph management tool called Shoebox. Alongside simple browsing features such as folders, thumbnails and timelines, Shoebox has some advanced multimedia features: content-based image retrieval and speech recognition applied to voice annotations. Our results suggest that participants found their digital photos much easier to manage than their non-digital ones, but that this advantage was almost entirely due to the simple browsing features. The advanced features were not used very often and their perceived utility was low. These results should help to inform the design of improved tools for managing personal digital photographs.

In current systems for browsing image collections, users are presented with sets of thumbnail images arranged in some default order on the screen. We are investigating whether it benefits users to have sets of thumbnails arranged according to their mutual similarity, so images that are alike are placed together. There are, of course, many possible definitions of "similarity": so far we have explored measurements based on low-level visual features, and on the textual captions assigned to the images. Here we describe two experiments, both involving designers as the participants, examining whether similarity-based arrangements of the candidate images are helpful for a picture selection task. Firstly, the two types of similarity-based arrangement were informally compared. Then, an arrangement based on visual similarity was more formally compared with a control of a random arrangement. We believe this work should be of interest to anyone designing a system that involves presenting sets of images to users. Keywords Image retrieval, information visualisation, evaluation.

No abstract available.

This paper reports recent work at ORL on segmentation of digital audio/video recordings. Firstly, we describe an audio segmentation algorithm that partitions a soundtrack into manageably sized segments for speech recognition. Secondly, we present an algorithm for detecting camera shot-break locations in the video. The output of these two algorithms is combined to produce a semantically meaningful segmentation of audio/video content, appropriate for information retrieval. We report the success of the algorithms in the context of television news retrieval.

We present a methodology for the formal specification and development of software systems using Z and the refinement calculus. The methodology combines the data structuring capabilities and the codified discrete mathematics of Z with the data encapsulation properties and development style of the refinement calculus, and it aims to provide a formal path from design to implementation without unnecessary transformations of notation or the definition of a new calculus. It is illustrated here by the development of two systems, a simply diary and (part of)a text editor, and is contrasted with the use of Z on its own. We discuss related and future work and conclude with some general comments on applied formal methods.

Abstract Continuing advances in VLSI fabrication technology are allowing circuit designs to become more and more complex and are thereby fuelling the need for ever‐faster digital simulators. In this paper, we investigate a multi‐transputer‐based method for speeding up gate‐level digital timing simulation, the acknowledged 'workhorse' of the digital circuit design verification process. In particular, we describe a variant of the basic conservative method for distributed discrete‐event simulation and we present PARSIM, a gate‐level digital timing simulator which is based on this method and which runs on arrays of transputers. Preliminary results on small transputer arrays demonstrate good speed‐ups for bitslice partitions of circuits with regular structure, including supralinear speed‐ups for a large (1664‐gate) circuit. Although these results are encouraging, poor results for less‐than‐ideal partitions of our test circuits suggest that we require an improvement in the efficiency of deadlock resolution and/or a means of automated optimized partitioning before PARSIM can be used as a practical tool for speeding up gate‐level simulation.