Publications

FXPAL publishes in top scientific conferences and journals.

2013
Publication Details
  • The International Symposium on Pervasive Displays
  • Jun 4, 2013

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Existing user interfaces for the configuration of large shared displays with multiple inputs and outputs usually do not allow users easy and direct configuration of the display's properties such as window arrangement or scaling. To address this problem, we are exploring a gesture-based technique for manipulating display windows on shared display systems. To aid target selection under noisy tracking conditions, we propose VoroPoint, a modified Voronoi tessellation approach that increases the selectable target area of the display windows. By maximizing the available target area, users can select and interact with display windows with greater ease and precision.

Private Aggregation for Presence Streams

Publication Details
  • Future Generation Computer Systems
  • May 28, 2013

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Collaboration technologies must support information sharing between collaborators, but must also take care not to share too much information or share information too widely. Systems that share information without requiring an explicit action by a user to initiate the sharing must be particularly cautious in this respect. Presence systems are an emerging class of applications that support collaboration. Through the use of pervasive sensors, these systems estimate user location, activities, and available communication channels. Because such presence data are sensitive, to achieve wide-spread adoption, sharing models must reflect the privacy and sharing preferences of their users. This paper looks at the role that privacy-preserving aggregation can play in addressing certain user sharing and privacy concerns with respect to presence data. We define conditions to achieve CollaPSE (Collaboration Presence Sharing Encryption) security, in which (i) an individual has full access to her own data, (ii) a third party performs computation on the data without learning anything about the data values, and (iii) people with special privileges called “analysts” can learn statistical information about groups of individuals, but nothing about the individual values contributing to the statistic other than what can be deduced from the statistic. More specifically, analysts can decrypt aggregates without being able to decrypt the individual values contributing to the aggregate. Based in part on studies we carried out that illustrate the need for the conditions encapsulated by CollaPSE security, we designed and implemented a family of CollaPSE protocols. We analyze their security, discuss efficiency tradeoffs, describe extensions, and review more recent privacy-preserving aggregation work.

Leading People to Longer Queries

Publication Details
  • CHI 2013
  • Apr 27, 2013

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Although longer queries can produce better results for information seeking tasks, people tend to type short queries. We created an interface designed to encourage people to type longer queries, and evaluated it in two Mechanical Turk experiments. Results suggest that our interface manipulation may be effective for eliciting longer queries.
Publication Details
  • IUI 2013
  • Mar 19, 2013

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People frequently capture photos with their smartphones, and some are starting to capture images of documents. However, the quality of captured document images is often lower than expected, even when applications that perform post-processing to improve the image are used. To improve the quality of captured images before post-processing, we developed a Smart Document Capture (SmartDCap) application that provides real-time feedback to users about the likely quality of a captured image. The quality measures capture the sharpness and framing of a page or regions on a page, such as a set of one or more columns, a part of a column, a figure, or a table. Using our approach, while users adjust the camera position, the application automatically determines when to take a picture of a document to produce a good quality result. We performed a subjective evaluation comparing SmartDCap and the Android Ice Cream Sandwich (ICS) camera application; we also used raters to evaluate the quality of the captured images. Our results indicate that users find SmartDCap to be as easy to use as the standard ICS camera application. Additionally, images captured using SmartDCap are sharper and better framed on average than images using the ICS camera application.

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Motivated by the addition of gyroscopes to a large number of new smart phones, we study the effects of combining accelerometer and gyroscope data on the recognition rate of motion gesture recognizers with dimensionality constraints. Using a large data set of motion gestures we analyze results for the following algorithms: Protractor3D, Dynamic Time Warping (DTW) and Regularized Logistic Regression (LR). We chose to study these algorithms because they are relatively easy to implement, thus well suited for rapid prototyping or early deployment during prototyping stages. For use in our analysis, we contribute a method to extend Protractor3D to work with the 6D data obtained by combining accelerometer and gyroscope data. Our results show that combining accelerometer and gyroscope data is beneficial also for algorithms with dimensionality constraints and improves the gesture recognition rate on our data set by up to 4%.
Publication Details
  • IUI 2013
  • Mar 19, 2013

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We describe direct video manipulation interactions applied to screen-based tutorials. In addition to using the video timeline, users of our system can quickly navigate into the video by mouse-wheel, double click over a rectangular region to zoom in and out, or drag a box over the video canvas to select text and scrub the video until the end of a text line even if not shown in the current frame. We describe the video processing techniques developed to implement these direct video manipulation techniques, and show how there are implemented to run in most modern web browsers using HTML5's CANVAS and Javascript.
Publication Details
  • SPIE Electronic Imaging 2013
  • Feb 3, 2013

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Video is becoming a prevalent medium for e-learning. Lecture videos contain useful information in both the visual and aural channels: the presentation slides and lecturer's speech respectively. To extract the visual information, we apply video content analysis to detect slides and optical character recognition (OCR) to obtain their text. Automatic speech recognition (ASR) is used similarly to extract spoken text from the recorded audio. These two text sources have distinct characteristics and relative strengths for video retrieval. We perform controlled experiments with manually created ground truth for both the slide and spoken text from more than 60 hours of lecture video. We compare the automatically extracted slide and spoken text in terms of accuracy relative to ground truth, overlap with one another, and utility for video retrieval. Experiments reveal that automatically recovered slide text and spoken text contain different content with varying error profiles. Additional experiments demonstrate higher precision video retrieval using automatically extracted slide text.  
2012
Publication Details
  • IPIN2012
  • Nov 13, 2012

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We describe Explorer, a system utilizing mirror worlds - dynamic 3D virtual models of physical spaces that reflect the structure and activities of those spaces to help support navigation, context awareness and tasks such as planning and recollection of events. A rich sensor network dynamically updates the models, determining the position of people, status of rooms, or updating textures to reflect displays or bulletin boards. Through views on web pages, portable devices, or on 'magic window' displays located in the physical space, remote people may 'Clook in' to the space, while people within the space are provided with augmented views showing information not physically apparent. For example, by looking at a mirror display, people can learn how long others have been present, or where they have been. People in one part of a building can get a sense of activities in the rest of the building, know who is present in their office, and look in to presentations in other rooms. A spatial graph is derived from the 3D models which is used both to navigational paths and for fusion of acoustic, WiFi, motion and image sensors used for positioning. We describe usage scenarios for the system as deployed in two research labs, and a conference venue.
Publication Details
  • IPIN2012
  • Nov 13, 2012

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Audio-based receiver localization in indoor environ-ments has multiple applications including indoor navigation, loca-tion tagging, and tracking. Public places like shopping malls and consumer stores often have loudspeakers installed to play music for public entertainment. Similarly, office spaces may have sound conditioning speakers installed to soften other environmental noises. We discuss an approach to leverage this infrastructure to perform audio-based localization of devices requesting local-ization in such environments, by playing barely audible controlled sounds from multiple speakers at known positions. Our approach can be used to localize devices such as smart-phones, tablets and laptops to sub-meter accuracy. The user does not need to carry any specialized hardware. Unlike acoustic approaches which use high-energy ultrasound waves, the use of barely audible (low energy) signals in our approach poses very different challenges. We discuss these challenges, how we addressed those, and experimental results on two prototypical implementations: a request-play-record localizer, and a continuous tracker. We evaluated our approach in a real world meeting room and report promising initial results with localization accuracy within half a meter 94% of the time. The system has been deployed in multiple zones of our office building and is now part of a location service in constant operation in our lab.
Publication Details
  • ICPR 2012
  • Nov 11, 2012

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Images of document pages have different characteristics than images of natural scenes, and so the sharpness measures developed for natural scene images do not necessarily extend to document images primarily composed of text. We present an efficient and simple method for effectively estimating the sharpness/ blurriness of document images that also performs well on natural scenes. Our method can be used to predict the sharpness in scenarios where images are blurred due to camera-motion (or hand-shake), defocus, or inherent properties of the imaging system. The proposed method outperforms the perceptually-based, no-reference sharpness work of [1] and [4], which was shown to perform better than 14 other no-reference sharpness measures on the LIVE dataset.
Publication Details
  • ACM Multimedia 2012
  • Oct 29, 2012

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Paper and Computers have complementary advantages and are used side by side in many scenarios. Interactive paper systems aim to combine the two media. However, most such systems only allow fingers and pens to interact with content on paper. This finger-pen-only input suffers from low precision, lag, instability and occlusion. Moreover, it incurs frequent device switch (e.g. pen vs. mouse) in users' hand during cross-media interactions, yielding inefficiency and interruptions of a document workspace continuum. To address these limitations, we propose MixPad, a novel interactive paper system which incorporates mice and keyboards to enhance the conventional pen-finger-based paper interaction. Similar to many other systems, MixPad adopts a mobile camera-projector unit to recognize paper documents, detect pen and finger gestures and provide visual feedback. Unlike these systems, MixPad supports users to use mice and keyboards to select fine-grained content and create annotation on paper, and to facilitate bimanual operations for more efficient and smoother cross-media interaction. This novel interaction style combines the advantages of mice, keyboards, pens and fingers, enabling richer digital functions on paper.
Publication Details
  • ACM Multimedia 2012
  • Oct 29, 2012

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Faithful sharing of screen contents is an important collaboration feature. Prior systems were designed to operate over constrained networks. They performed poorly even without such bottlenecks. To build a high performance screen sharing system, we empirically analyzed screen contents for a variety of scenarios. We showed that screen updates were sporadic with long periods of inactivity. When active, screens were updated at far higher rates than was supported by earlier systems. The mismatch was pronounced for interactive scenarios. Even during active screen updates, the number of updated pixels were frequently small. We showed that crucial information can be lost if individual updates were merged. When the available system resources could not support high capture rates, we showed ways in which updates can be effectively collapsed. We showed that Zlib lossless compression performed poorly for screen updates. By analyzing the screen pixels, we developed a practical transformation that significantly improved compression rates. Our system captured 240 updates per second while only using 4.6 Mbps for interactive scenarios. Still, while playing movies in fullscreen mode, our approach could not achieve higher capture rates than prior systems; the CPU remains the bottleneck. A system that incorporates our findings is deployed within the lab.
Publication Details
  • ACM Multimedia '12
  • Oct 29, 2012

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DisplayCast is a many to many screen sharing system that is targeted towards Intranet scenarios. The capture software runs on all computers whose screens need to be shared. It uses an application agnostic screen capture mechanism that creates a sequence of pixmap images of the screen updates. It transforms these pixmaps to vastly improve the lossless Zlib compression performance. These algorithms were developed after an extensive analysis of typical screen contents. DisplayCast shares the processor and network resources required for screen capture, compression and transmission with host applications whose output needs to be shared. It balances the need for high performance screen capture with reducing its resource interference with user applications. DisplayCast uses Zeroconf for naming and asynchronous location. It provides support for Cisco WiFi and Bluetooth based localization. It also includes a HTTP/REST based controller for remote session initiation and control. DisplayCast supports screen capture and playback in computers running Windows 7 and Mac OS X operating systems. Remote screens can be archived into a H.264 encoded movie on a Mac. They can also be played back in real time on Apple iPhones and iPads. The software is released under a New BSD license.
Publication Details
  • CIKM 2012 Books Online Workshop Keynote Address
  • Oct 29, 2012

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Reading is part of how we understand the world, how we share knowledge, how we play, and even how we think. Although reading text is the dominant form of reading, most of the text we read— letters, numbers, words, and sentences—is surrounded by illustrations, photographs, and other kinds of symbols that we include as we read. As dynamic displays migrate into the real world at many scales, whether personal devices, handhelds, or large screens in both interior and exterior spaces, opportunities for reading migrate as well. As has happened continually throughout the history of reading, new technologies, physical forms and social patterns create new genres, which themselves may then combine or collide to morph into something new. At PARC, the RED (Research in Experimental Design) group examined emerging technologies for impact on media and the human relationship to information, especially reading. We explored new ways of experiencing text: new genres, new styles of interaction, and unusual media. Among the questions we considered: how might “the book” change? More particularly, how does the experience of reading change with the introduction of new technologies…and how does it remain the same? In this talk, we'll discuss the ideas behind the design and research process that led to creating eleven different experiences of new forms of reading. We’ll also consider how our technological context for reading has changed in recent years, and what influence the lessons from XFR may have on our ever-developing online reading experiences.

Through the Looking-Glass: Mirror Worlds for Augmented Awareness & Capability

Publication Details
  • ACM MM 2012
  • Oct 29, 2012

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We describe a system for supporting mirror worlds - 3D virtual models of physical spaces that reflect the structure and activities of those spaces to help support context awareness and tasks such as planning and recollection of events. Through views on web pages, portable devices, or on 'magic window' displays located in the physical space, remote people may 'look in' to the space, while people within the space are provided information not apparent through unaided perception. For example, by looking at a mirror display, people can learn how long others have been present, or where they have been. People in one part of a building can get a sense of activities in the rest of the building, know who is present in their office, and look in to presentations in other rooms. The system can be used to bridge across sites and help provide different parts of an organization with a shared awareness of each other's space and activities. We describe deployments of our mirror world system at several locations.
Publication Details
  • Mobile HCI 2012 demo track
  • Sep 21, 2012

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In this demonstration we will show a mobile remote control and monitoring application for a recipe development laboratory at a local chocolate production company. In collaboration with TCHO, a chocolate maker in San Francisco, we built a mobile Web app designed to allow chocolate makers to control their laboratory's machines. Sensor data is imported into the app from each machine in the lab. The mobile Web app is used for control, monitoring, and collaboration. We have tested and deployed this system at the real-world factory and it is now in daily use. This project is designed as part of a research exploration into enhanced collaboration in industrial settings between physically remote people and places, e.g. factories in China with clients in the US.
Publication Details
  • Workshop on Social Mobile Video and Panoramic Video
  • Sep 20, 2012

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The ways in which we come to know and share what we know with others are deeply entwined with the technologies that enable us to capture and share information. As face-to-face communication has been supplemented with ever-richer media––textual books, illustrations and photographs, audio, film and video, and more––the possibilities for knowledge transfer have only expanded. One of the latest trends to emerge amidst the growth of Internet sharing and pervasive mobile devices is the mass creation of online instructional videos. We are interested in exploring how smart phones shape this sort of mobile, rich media documentation and sharing.
Publication Details
  • USENIX/ACM/IFIP Middleware
  • Sep 19, 2012

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Faunus addresses the challenge of specifying and managing complex collaboration sessions. Many entities from various administrative domains orchestrate such sessions. Faunus decouples the entities that specify the session from entities that activate and manage them. It restricts the operations to specific agents using capabilities. It unifies the specification and management operations through its naming system. Each Faunus name is persistent and globally unique. A collection of attributes are attached to each name. Together, they represent a collection of services that form a collaboration session. Anyone can create a name; the creator has full read and write privileges that can be delegated to others. With the proper capability, anyone can modify session attributes between an active and inactive state. Though the system is designed for Internet scale deployments, the security model for providing and revoking capabilities currently assumes an Intranet style deployment. We have incorporated Faunus into a DisplayCast system that originally used Zeroconf. We are incorporating Faunus into another project that will fully exercise the power of Faunus.
Publication Details
  • International Journal on Document Analysis and Recognition (IJDAR): Volume 15, Issue 3 (2012), pp. 167-182.
  • Sep 1, 2012

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When searching or browsing documents, the genre of a document is an important consideration that complements topical characterization. We examine design considerations for automatic tagging of office document pages with genre membership. These include selecting features that characterize genre-related information in office documents, examining the utility of text-based features and image-based features, and proposing a simple ensemble method to improve genre identification performance. In the open-set identification of four office document genres, our experiments show that when combined with image-based features, text-based features do not significantly influence performance. These results provide support for a topic-independent approach to genre identification of office documents. Experiments also show that our simple ensemble method significantly improves performance relative to using a support vector machine (SVM) classifier alone. We demonstrate the utility of our approach by integrating our automatic genre tags in a faceted search and browsing application for office document collections.
Publication Details
  • IIiX 2012
  • Aug 21, 2012

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Exploratory search activities tend to span multiple sessions and involve finding, analyzing and evaluating information and collab-orating with others. Typical search systems, on the other hand, are designed to support a single searcher, precision-oriented search tasks. We describe a search interface and system design of a multi-session exploratory search system, discuss design challenges en-countered, and chronicle the evolution of our design. Our design describes novel displays for visualizing retrieval history infor-mation, and introduces ambient displays and persuasive elements to interactive information retrieval.
Publication Details
  • DIS (Designing Interactive Systems) 2012 Demos track
  • Jun 11, 2012

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We will demonstrate successive and final stages in the iterative design of a complex mixed reality system in a real-world factory setting. In collaboration with TCHO, a chocolate maker in San Francisco, we built a virtual “mirror” world of a real-world chocolate factory and its processes. Sensor data is imported into the multi-user 3D environment from hundreds of sensors and a number of cameras on the factory floor. The resulting virtual factory is used for simulation, visualization, and collaboration, using a set of interlinked, real-time layers of information. It can be a stand-alone or a web-based application, and also works on iOS and Android cell phones and tablet computers. A unique aspect of our system is that it is designed to enable the incorporation of lightweight social media-style interactions with co-workers along with factory data. Through this mixture of mobile, social, mixed and virtual technologies, we hope to create systems for enhanced collaboration in industrial settings between physically remote people and places, such as factories in China with managers in the US.
Publication Details
  • CHI 2012
  • May 7, 2012

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Affect influences workplace collaboration and thereby impacts a workplace's productivity. Participants in face-toface interactions have many cues to each other's affect, but work is increasingly carried out via computer-mediated channels that lack many of these cues. Current presence systems enable users to estimate the availability of other users, but not their affect states or communication preferences. This work investigates relationships between affect state and communication preferences and demonstrates the feasibility of estimating affect state and communication preferences from a presence state stream.
Publication Details
  • CHI 2012
  • May 5, 2012

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Abstract: Pico projectors have lately been investigated as mobile display and interaction devices. We propose to use them as ‘light beams’: Everyday objects sojourning in a beam are turned into dedicated projection surfaces and tangible interaction devices. While this has been explored for large projectors, the affordances of pico projectors are fundamentally different: they have a very small and strictly limited projection ray and can be carried around in a nomadic way during the day. Thus it is unclear how this could be actually leveraged for tangible interaction with physical, real world objects. We have investigated this in an exploratory field study and contribute the results. Based upon these, we present exemplary interaction techniques and early user feedback.

Designing a tool for exploratory information seeking

Publication Details
  • CHI 2012
  • May 5, 2012

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In this paper we describe our on-going design process in building a search system designed to support people's multi-session exploratory search tasks. The system, called Querium, allows people to run queries and to examine results as do conventional search engines, but it also integrates a sophisticated search history that helps people make sense of their search activity over time. Information seeking is a cognitively demanding process that can benefit from many kinds of information, if that information is presented appropriately. Our design process has been focusing on creating displays that facilitate on-going sense-making while keeping the interaction efficient, fluid, and enjoyable.

Querium: A Session-Based Collaborative Search System

Publication Details
  • European Conference on Information Retrieval 2012
  • Apr 1, 2012

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People's information-seeking can span multiple sessions, and can be collaborative in nature. Existing commercial offerings do not effectively support searchers to share, save, collaborate or revisit their information. In this demo paper we present Querium: a novel session-based collaborative search system that lets users search, share, resume and collaborate with other users. Querium provides a number of novel search features in a collaborative setting, including relevance feedback, query fusion, faceted search, and search histories