Publications

FXPAL publishes in top scientific conferences and journals.

2001
Publication Details
  • In Proceedings of the International Conference on Image Processing, Thessaloniki, Greece. October 7-10, 2001.
  • Oct 7, 2001

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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.
Publication Details
  • Proc. ACM Multimedia 2001, Ottawa,CA, Oct. 2001.
  • Sep 30, 2001

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We describe a system called FlyAbout which uses spatially indexed panoramic video for virtual reality applications. Panoramic video is captured by moving a 360° camera along continuous paths. Users can interactively replay the video with the ability to view any interesting object or choose a particular direction. Spatially indexed video gives the ability to travel along paths or roads with a map-like interface. At junctions, or intersection points, users can chose which path to follow as well as which direction to look, allowing interaction not available with conventional video. Combining the spatial index with a spatial database of maps or objects allows users to navigate to specific locations or interactively inspect particular objects.
Publication Details
  • Proc. International Conference on Computer Music (ICMC), Habana, Cuba, September 2001.
  • Sep 12, 2001

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This paper presents a novel approach to visualizing the time structure of musical waveforms. The acoustic similarity between any two instants of an audio recording is displayed in a static 2D representation, which makes structural and rhythmic characteristics visible. Unlike practically all prior work, this method characterizes self-similarity rather than specific audio attributes such as pitch or spectral features. Examples are presented for classical and popular music.
Publication Details
  • IEEE Computer, 34(9), pp. 61-67
  • Sep 1, 2001

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To meet the diverse needs of business, education, and personal video users, the authors developed three visual interfaces that help identify potentially useful or relevant video segments. In such interfaces, keyframes-still images automatically extracted from video footage-can distinguish videos, summarize them, and provide access points. Well-chosen keyframes enhance a listing's visual appeal and help users select videos. Keyframe selection can vary depending on the application's requirements: A visual summary of a video-captured meeting may require only a few highlight keyframes, a video editing system might need a keyframe for every clip, while a browsing interface requires an even distribution of keyframes over the video's full length. The authors conducted user studies for each of their three interfaces, gathering input for subsequent interface improvements. The studies revealed that finding a similarity measure for collecting video clips into groups that more closely match human perception poses a challenge. Another challenge is to further improve the video-segmentation algorithm used for selecting keyframes. A new version will provide users with more information and control without sacrificing the interface's ease of use.

Recording the Region of Interest from FlyCam Panoramic Video

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  • Proc. International Conference on Image Processing, Thessaloniki, Greece, September 2001.
  • Sep 1, 2001

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A novel method for region of interest tracking and recording video is presented. The proposed method is based on the FlyCam system, which produces high resolution and wide-angle video sequences by stitching the video frames from multiple stationary cameras. The method integrates tracking and recording processes, and targets applications such as classroom lectures and video conferencing. First, the region of interest (which typically covers the speaker) is tracked using a Kalman filter. Then, the Kalman filter estimation results are used for virtual camera control and to record the video. The system has no physical camera motion and the virtual camera parameters are readily available for video indexing. The proposed system has been implemented for real time recording of lectures and presentations.

The Beat Spectrum: A New Approach to Rhythm Analysis

Publication Details
  • In Proceedings of the International Conference on Multimedia and Expo 2001 (ICME), Tokyo, Japan. August 22-25, 2001.
  • Aug 25, 2001

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We introduce the beat spectrum, a new method of automatically characterizing the rhythm and tempo of music and audio. The beat spectrum is a measure of acoustic self-similarity as a function of time lag. Highly structured or repetitive music will have strong beat spectrum peaks at the repetition times. This reveals both tempo and the relative strength of particular beats, and therefore can distinguish between different kinds of rhythms at the same tempo. We also introduce the beat spectrogram which graphically illustrates rhythm variation over time. Unlike previous approaches to tempo analysis, the beat spectrum does not depend on particular attributes such as energy or frequency, and thus will work for any music or audio in any genre. We present tempo estimation results for a variety of musical genres, which are accurate to within 1%. This approach has a variety of applications, including music retrieval by similarity and automatically generating music videos.

The impact of text browsing on text retrieval performance

Publication Details
  • Information Processing and Management 37 (3) pp. 507-520
  • Aug 21, 2001

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The results from a series of three experiments that used Text Retrieval Conference (TREC) data and TREC search topics are compared. These experiments each involved three novel user interfaces (one per experiment). User interfaces that made it easier for users to view text were found to improve recall in all three experiments. A distinction was found between a cluster of subjects (a majority of whom were search experts) who tended to read fewer documents more carefully (readers, or exclusives) and subjects who skimmed through more documents without reading them as carefully (skimmers, or inclusives). Skimmers were found to have significantly better recall overall. A major outcome from our experiments at TREC and with the TREC data, is that hypertext interfaces to information retrieval (IR) tasks tend to increase recall. Our interpretation of this pattern of results across the three experiments is that increased interaction with the text (more pages viewed) generally improves recall. Findings from one of the experiments indicated that viewing a greater diversity of text on a single screen (i.e., not just more text per se, but more articles available at once) may also improve recall. In an experiment where a traditional (type-in) query interface was contrasted with a condition where queries were marked up on the text, the improvement in recall due to viewing more text was more pronounced with search novices. Our results demonstrate that markup and hypertext interfaces to text retrieval systems can benefit recall and can also benefit novices. The challenge now will be to find modified versions of hypertext interfaces that can improve precision, as well as recall and that can work with users who prefer to use different types of search strategy or have different types of training and experience.

m-Links: An Infrastructure for Very Small Internet Devices

Publication Details
  • The 7th Annual International Conference on Mobile Computing and Networking (MOBICOM 2001), Rome, Italy, July 16-21 2001, ACM Press, 2001, pp. 122-131.
  • Jul 16, 2001

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In this paper we describe the Mobile Link (m-Links) infrastructure for utilizing existing World Wide Web content and services on wireless phones and other very small Internet terminals. Very small devices, typically with 3-20 lines of text, provide portability and other functionality while sacrificing usability as Internet terminals. In order to provide access on such limited hardware we propose a small device web navigation model that is more appropriate than the desktop computers web browsing model. We introduce a middleware proxy, the Navigation Engine, to facilitate the navigation model by concisely displaying the Webs link (i.e., URL) structure. Because not all Web information is appropriately "linked," the Navigation Engine incorporates data-detectors to extract bits of useful information such as phone numbers and addresses. In order to maximize program-data composibility, multiple network-based services (similar to browser plug-ins) are keyed to a links attributes such as its MIME type. We have built this system with an emphasis on user extensibility and we describe the design and implementation as well as a basic set of middleware services that we have found to be particularly important.
Publication Details
  • The Eighth IFIP TC.13 Conference On Human-Computer Interaction (INTERACT 2001). Tokyo, Japan, July 9-13, 2001.
  • Jul 9, 2001

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The two most commonly used techniques for evaluating the fit between application design and use - namely, usability testing and beta testing with user feedback - suffer from a number of limitations that restrict evaluation scale (in the case of usability tests) and data quality (in the case of beta tests). They also fail to provide developers with an adequate basis for: (1) assessing the impact of suspected problems on users at large, and (2) deciding where to focus development and evaluation resources to maximize the benefit for users at large. This paper describes an agent-based approach for collecting usage data and user feedback over the Internet that addresses these limitations to provide developers with a complementary source of usage- and usability-related information. Contributions include: a theory to motivate and guide data collection, an architecture capable of supporting very large scale data collection, and real-word experience suggesting the proposed approach is complementary to existing practice.
Publication Details
  • In Proceedings of Human-Computer Interaction (INTERACT '01), IOS Press, Tokyo, Japan, pp. 464-471
  • Jul 9, 2001

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Hitchcock is a system to simplify the process of editing video. Its key features are the use of automatic analysis to find the best quality video clips, an algorithm to cluster those clips into meaningful piles, and an intuitive user interface for combining the desired clips into a final video. We conducted a user study to determine how the automatic clip creation and pile navigation support users in the editing process. The study showed that users liked the ease-of-use afforded by automation, but occasionally had problems navigating and overriding the automated editing decisions. These findings demonstrate the need for a proper balance between automation and user control. Thus, we built a new version of Hitchcock that retains the automatic editing features, but provides additional controls for navigation and for allowing users to modify the system decisions.

Designing e-Books for Legal Research.

Publication Details
  • In Proceedings of JCDL 2001 (Roanoke, VA, June 23-27). ACM Press. pp. 41-48.
  • Jun 23, 2001

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In this paper we report the findings from a field study of legal research in a first-tier law school and on the resulting redesign of XLibris, a next-generation e-book. We first characterize a work setting in which we expected an e-book to be a useful interface for reading and otherwise using a mix of physical and digital library materials, and explore what kinds of reading-related functionality would bring value to this setting. We do this by describing important aspects of legal research in a heterogeneous information environment, including mobility, reading, annotation, link following and writing practices, and their general implications for design. We then discuss how our work with a user community and an evolving e-book prototype allowed us to examine tandem issues of usability and utility, and to redesign an existing e-book user interface to suit the needs of law students. The study caused us to move away from the notion of a stand-alone reading device and toward the concept of a document laptop, a platform that would provide wireless access to information resources, as well as support a fuller spectrum of reading-related activities.

Quiet Calls: Talking Silently on Mobile Phones

Publication Details
  • In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, pp. 174-181, ACM Press, March 31-April 5, 2001, Seattle, WA.
  • Mar 30, 2001
Publication Details
  • In Proceedings of the Thirty-fourth Annual Hawaii International Conference on System Sciences (HICSS), Big Island, Hawaii. January 7-12, 2001.
  • Feb 7, 2001

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This paper describes a new system for panoramic two-way video communication. Digitally combining images from an array of inexpensive video cameras results in a wide-field panoramic camera, from inexpensive off-the-shelf hardware. This system can aid distance learning in several ways, by both presenting a better view of the instructor and teaching materials to the students, and by enabling better audience feedback to the instructor. Because the camera is fixed with respect to the background, simple motion analysis can be used to track objects and people of interest. Electronically selecting a region of this results in a rapidly steerable "virtual camera." We present system details and a prototype distance-learning scenario using multiple panoramic cameras.
Publication Details
  • WebNet 2001 World Conference on the WWW and Internet, Orlando, FL
  • Jan 17, 2001

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As more information is made available online, users collect information in personal information spaces like bookmarks and emails. While most users feel that organizing these collections is crucial to improve access, studies have shown that this activity is time consuming and highly cognitive. Automatic classification has been used but by relying on the full text of the documents, they do not generate personalized classifications. Our approach is to give users the ability to annotate their documents as they first access them. This annotation tool is unobtrusive and welcome by most users who generally miss this facility when dealing with digital documents. Our experiments show that these annotations can be used to generate personalized classifications of annotated Web pages.

Description and Narrative in Hypervideo

Publication Details
  • Proceedings of the Thirty-Fourth Annual Hawaii International Conference on System Sciences
  • Jan 3, 2001

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While hypertext was originally conceived for the management of scientific and technical information, it has been embraced with great enthusiasm by several members of the literary community for the promises it offers towards new approaches to narrative. Experiments with hypertext-based interactive narrative were originally based solely on verbal text but have more recently extended to include digital video artifacts. The most accomplished of these experiments, HyperCafe, provided new insights into the nature of narrative and how it may be presented; but it also offered an opportunity to reconsider other text types. This paper is an investigation of the application of an approach similar to HyperCafe to a descriptive text. We discuss how the approach serves the needs of description and illustrate the discussion with a concrete example. We then conclude by considering the extent to which our experiences with description may be applied to our continuing interest in narrative.
2000
Publication Details
  • Multimedia Modeling: Modeling Multimedia Information and Systems, Nagano, Japan
  • Nov 12, 2000

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While hypermedia is usually presented as a way to offer content in a nonlinear manner, hypermedia structure tends to reinforce the assumption that reading is basically a linear process. Link structures provide a means by which the reader may choose different paths to traverse; but each of these paths is fundamentally linear, revealed through either a block of text or a well-defined chain of links. While there are experiences that get beyond such linear constraints, such as driving a car, it is very hard to capture this kind of non-linearity, characterized by multiple sources of stimuli competing for attention, in a hypermedia document. This paper presents a multi-channel document infrastructure that provides a means by which all such sources of attention are presented on a single "page" (i.e., a display with which the reader interacts) and move between background and foreground in response to the activities of the reader. The infrastructure thus controls the presentation of content with respect to four dimensions: visual, audio, interaction support, and rhythm.