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Proceedings of Pervasive 2009: International Conference on Pervasive Computing

Fullname:Pervasive 2009: Pervasive Computing, 7th International Conference
Editors:Hideyuki Tokuda; Michael Beigl; Adrian Friday; A. J. Bernheim Brush; Yoshito Tobe
Location:Nara, Japan
Dates:2009-May-11 to 2009-May-14
Publisher:Springer-Verlag
Series:Lecture Notes in Computer Science 5538 Springer 2009
Standard No:ISBN 978-3-642-01515-1; hcibib: Pervasive09
Papers:27
Pages:405
Links:Online Proceedings
  1. Digital Displays
  2. Navigation
  3. At Home with Pervasive Applications
  4. Sensors, Sensors, Everywhere
  5. Working Together
  6. Tagging and Tracking
  7. Methods and Tools
  8. The Importance of Context

Digital Displays

Display Blindness: The Effect of Expectations on Attention towards Digital Signage BIBAFull-Text 1-8
  Jörg Müller; Dennis Wilmsmann; Juliane Exeler; Markus Buzeck; Albrecht Schmidt; Tim Jay; Antonio Krüger
In this paper we show how audience expectations towards what is presented on public displays can correlate with their attention towards these displays. Similar to the effect of Banner Blindness on the Web, displays for which users expect uninteresting content (e.g. advertisements) are often ignored. We investigate this effect in two studies. In the first, interviews with 91 users at 11 different public displays revealed that for most public displays, the audience expects boring advertisements and so ignores the displays. This was exemplified by the inclusion of two of our own displays. One, the iDisplay, which showed information for students, was looked at more often than the other (MobiDiC) which showed coupons for shops. In a second study, we conducted repertory grid interviews with 17 users to identify the dimensions that users believe to influence whether they look at public displays. We propose possible solutions to overcome this "Display Blindness" and increase audience attention towards public displays.
Users' View on Context-Sensitive Car Advertisements BIBAFull-Text 9-16
  Florian Alt; Christoph Evers; Albrecht Schmidt
Cars are ubiquitous and offer large and often highly visible surfaces that can be used as advertising space. Until now, advertising in this domain has focused on commercial vehicles, and advertisements have been painted on and were therefore static, with the exception of car-mounted displays that offer dynamic content. With new display technologies, we expect static displays or uniformly-painted surfaces (e.g. onto car doors or the sides of vans and trucks) to be replaced with embedded dynamic displays. We also see an opportunity for advertisements to be placed on non-commercial cars: results of our online survey with 187 drivers show that more than half of them have an interest in displaying advertising on their cars under two conditions: (1) they will receive financial compensation, and (2) there will be a means for them to influence the type of advertisements shown. Based on these findings, as well as further interviews with car owners and a car fleet manager, we discuss the requirements for a context-aware advertising platform, including a context-advertising editor and contextual content distribution system. We describe an implementation of the system that includes components for car owners to describe their preferences and for advertisers to contextualize their ad content and distribution mechanism.
ReflectiveSigns: Digital Signs That Adapt to Audience Attention BIBAFull-Text 17-24
  Jörg Müller; Juliane Exeler; Markus Buzeck; Antonio Krüger
This paper presents ReflectiveSigns, i.e. digital signage (public electronic displays) that automatically learns the audience preferences for certain content in different contexts and presents content accordingly. Initially, content (videos, images and news) are presented in a random manner. Using cameras installed on the signs, the system observes the audience and detects if someone is watching the content (via face detection). The anonymous view time duration is then stored in a central database, together with date, time and sign location. When scheduling content, the signs calculate the expected view time for each content type depending on sign location and time using a Naive Bayes classifier. Content is then selected randomly, with the probability for each content weighted by the expected view time. The system has been deployed for two months on four digital signs in a university setting using semi-realistic content & content types. We present a first evaluation of this approach that concentrates on major effects and results from interviews with 15 users.

Navigation

Realistic Driving Trips For Location Privacy BIBAKFull-Text 25-41
  John Krumm
Simulated, false location reports can be an effective way to confuse a privacy attacker. When a mobile user must transmit his or her location to a central server, these location reports can be accompanied by false reports that, ideally, cannot be distinguished from the true one. The realism of the false reports is important, because otherwise an attacker could filter out all but the real data. Using our database of GPS tracks from over 250 volunteer drivers, we developed probabilistic models of driving behavior and applied the models to create realistic driving trips. The simulations model realistic start and end points, slightly non-optimal routes, realistic driving speeds, and spatially varying GPS noise.
Keywords: location privacy; location-based services; false trips; GPS
Enhancing Navigation Information with Tactile Output Embedded into the Steering Wheel BIBAFull-Text 42-58
  Dagmar Kern; Paul Marshall; Eva Hornecker; Yvonne Rogers; Albrecht Schmidt
Navigation systems are in common use by drivers and typically present information using either audio or visual representations. However, there are many pressures on the driver's cognitive systems in a car and navigational systems can add to this complexity. In this paper, we present two studies which investigated how vibro-tactile representations of navigational information, might be presented to the driver via the steering wheel to ameliorate this problem. Our results show that adding tactile information to existing audio, or particularly visual representations, can improve both driving performance and experience.
Landmark-Based Pedestrian Navigation with Enhanced Spatial Reasoning BIBAFull-Text 59-76
  Harlan Hile; Radek Grzeszczuk; Alan L. Liu; Ramakrishna Vedantham; Jana Kosecka; Gaetano Borriello
Computer vision techniques can enhance landmark-based navigation by better utilizing online photo collections. We use spatial reasoning to compute camera poses, which are then registered to the world using GPS information extracted from the image tags. Computed camera pose is used to augment the images with navigational arrows that fit the environment. We develop a system to use high-level reasoning to influence the selection of landmarks along a navigation path, and lower-level reasoning to select appropriate images of those landmarks. We also utilize an image matching pipeline based on robust local descriptors to give users of the system the ability to capture an image and receive navigational instructions overlaid on their current context. These enhancements to our previous navigation system produce a more natural navigation plan and more understandable images in a fully automatic way.

At Home with Pervasive Applications

The Acceptance of Domestic Ambient Intelligence Appliances by Prospective Users BIBAKFull-Text 77-94
  Somaya Ben Allouch; Jan van Dijk; Oscar Peters
Ambient intelligence (AmI) is a growing interdisciplinary area where the focus is shifted towards users instead of merely emphasizing the technological opportunities of AmI. Different methods are employed to understand the adoption of AmI appliances by users. However, these are often small-scale methods that are focused on specific subgroups. Large scale quantitative studies to understand the adoption of AmI appliances are scarce. In this study, a questionnaire was designed to examine how the Dutch people (n = 1221) perceive AmI appliances for domestic settings. Findings show that intention to adopt AmI appliances was low and that respondents had a negative to neutral attitude towards AmI appliances. On the basis of structural equation analysis, results suggest that adoption of AmI appliances could be explained by outcome expectancies of AmI appliances. The potential implications of the findings are discussed.
Keywords: ambient intelligence; pervasive technologies; technology acceptance
Adding GPS-Control to Traditional Thermostats: An Exploration of Potential Energy Savings and Design Challenges BIBAFull-Text 95-114
  Manu Gupta; Stephen S. Intille; Kent Larson
Although manual and programmable home thermostats can save energy when used properly, studies have shown that over 40% of U.S. homes may not use energy-saving temperature setbacks when homes are unoccupied. We propose a system for augmenting these thermostats using just-in-time heating and cooling based on travel-to-home distance obtained from location-aware mobile phones. Analyzing GPS travel data from 8 participants (8-12 weeks each) and heating and cooling characteristics from 5 homes, we report results of running computer simulations estimating potential energy savings from such a device. Using a GPS-enabled thermostat might lead to savings of as much as 7% for some households that do not regularly use the temperature setback afforded by manual and programmable thermostats. Significantly, these savings could be obtained without requiring any change in occupant behavior or comfort level, and the technology could be implemented affordably by exploiting the ubiquity of mobile phones. Additional savings may be possible with modest context-sensitive prompting. We report on design considerations identified during a pilot test of a fully-functional implementation of the system.
KidCam: Toward an Effective Technology for the Capture of Children's Moments of Interest BIBAFull-Text 115-132
  Julie A. Kientz; Gregory D. Abowd
Mobile applications of automated capture present many interesting design challenges, balancing the desire for rich media against ease of use and availability. In particular, capturing rich media of young children has many potential benefits, but remains a difficult challenge due to the many unique constraints of recording children. Motivated by the aim of supporting a parent's need to record the life events of a young child, we have designed KidCam, a prototype rich media capture device. This paper presents the design, implementation, and evaluation of KidCam and its goal of addressing some of the challenges of recording young children. Results from a three-month study with four families show that KidCam addresses some of the challenges of recording rich media of children, but there are still remaining hurdles. We discuss these remaining challenges, potential ideas for how they could be addressed, and emergent uses for KidCam beyond the initial domain for the creation of family memories.

Sensors, Sensors, Everywhere

Mobile Device Interaction with Force Sensing BIBAKFull-Text 133-150
  James Scott; Lorna M. Brown; Mike Molloy
We propose a new type of input for mobile devices by sensing forces applied by users to device casings. Deformation of the devices is not necessary for such "force gestures" to be detectable. Our prototype implementation augments an ultra-mobile PC (UMPC) to detect twisting and bending forces. We describe examples of interactions using these forces, employing twisting to perform application switching (alt-tab) and interpreting bending as page-down/up. We present a user study exploring users' abilities to reliably apply twisting and bending forces to various degrees, and draw implications from this study for future force-based interfaces.
Keywords: Force; sensors; mobile devices; interaction
Inferring Identity Using Accelerometers in Television Remote Controls BIBAFull-Text 151-167
  Keng-hao Chang; Jeffrey Hightower; Branislav Kveton
We show that accelerometers embedded in a television remote control can be used to distinguish household members based on the unique way each person wields the remote. This personalization capability can be applied to enhance digital video recorders with show recommendations per family-member instead of per device or as an enabling technology for targeted advertising. Based on five 1-3 week data sets collected from real homes, using 372 features including key press codes, key press timing, and 3-axis acceleration parameters including dominant frequency, energy, mean, and variance, we show household member identification accuracy of 70-92% with a Max-Margin Markov Network (M3N) classifier.
The Effectiveness of Haptic Cues as an Assistive Technology for Human Memory BIBAKFull-Text 168-175
  Stacey Kuznetsov; Anind K. Dey; Scott E. Hudson
Many people experience difficulty recalling and recognizing information during everyday tasks. Prior assistive technology has leveraged audio and video cues, but this approach is often disruptive and inappropriate in socially-sensitive situations. Our work explores vibro-tactile feedback as an alternative that unobtrusively aids human memory. We conducted several user studies comparing within-participant performance on memory tasks without haptic cues (control) and tasks augmented with tactile stimuli (intervention). Our studies employed a bracelet prototype that emits vibratory pulses, which are uniquely mapped to audio and visual information. Results show interaction between performance on control and intervention conditions. Poor performers on unaided tasks improve recognition by more than 20% (p<0.05) when haptic cues are employed. Thus, we suggest vibro-tactile feedback as an effective memory aid for users with impaired memory, and offer several design recommendations for integrating haptic cues into wearable devices.
Keywords: Wearable computing; haptic interfaces; memory cues
Exploring Privacy Concerns about Personal Sensing BIBAFull-Text 176-183
  Predrag V. Klasnja; Sunny Consolvo; Tanzeem Choudhury; Richard Beckwith; Jeffrey Hightower
More and more personal devices such as mobile phones and multimedia players use embedded sensing. This means that people are wearing and carrying devices capable of sensing details about them such as their activity, location, and environment. In this paper, we explore privacy concerns about such personal sensing through interviews with 24 participants who took part in a three month study that used personal sensing to detect their physical activities. Our results show that concerns often depended on what was being recorded, the context in which participants worked and lived and thus would be sensed, and the value they perceived would be provided. We suggest ways in which personal sensing can be made more privacy-sensitive to address these concerns.

Working Together

Enabling Pervasive Collaboration with Platform Composition BIBAKFull-Text 184-201
  Trevor Pering; Roy Want; Barbara Rosario; Shivani Sud; Kent Lyons
Emerging pervasive computing technologies present many opportunities to aid ad-hoc collocated group collaboration. To better understand ad-hoc collaboration using pervasive technologies, or Pervasive Collaboration, a design space composed of three axes (composition granularity, sharing models, and resource references) is outlined, highlighting areas that are only partially covered by existing systems. Addressing some of these gaps, Platform Composition is a technique designed to overcome the usability limitations of small mobile devices and facilitate group activities in ad-hoc environments by enabling users to run legacy applications on a collection mobile devices. The associated Composition Framework prototype demonstrates a concrete implementation that explores the applicability of existing technologies, protocols, and applications to this model. Overall, Platform Composition promises to be an effective technique for supporting collaborative work on mobile devices, without requiring significant changes to the underlying computer platform or end-user applications.
Keywords: Pervasive technologies; ad-hoc collaboration; mobile devices; resource sharing; platform composition
Askus: Amplifying Mobile Actions BIBAFull-Text 202-219
  Shin'ichi Konomi; Niwat Thepvilojanapong; Ryohei Suzuki; Susanna Pirttikangas; Kaoru Sezaki; Yoshito Tobe
Information sharing has undeniably become ubiquitous in the Internet age. The global village created on the Internet provides people with instant access to information and news on events occurring in a remote area, including access to video content on websites such as YouTube. Thus, the Internet has helped us overcome barriers to information. However, we cannot conceive an event happening in a remote area and respond to it with relevant actions in a real-time fashion. To overcome this problem, we propose a system called Askus, a mobile platform for supporting networked actions. Askus facilitates an extension of the conceivable space and action by including humans in the loop. In Askus, a person's request is transmitted to a suitable person who will then act in accordance with the request at a remote site. Based on a diary study that led to detailed understanding about mobile assistance needs in everyday life, we developed the Askus platform and implemented the PC-based and mobile phone-based prototypes. We also present the results from our preliminary field trial.
Boxed Pervasive Games: An Experience with User-Created Pervasive Games BIBAKFull-Text 220-237
  Richard Wetzel; Annika Wærn; Staffan Jonsson; Irma Lindt; Peter Ljungstrand; Karl-Petter Åkesson
Pervasive games are rapidly maturing -- from early research experiments with locative games we now start to see a range of commercial projects using locative and pervasive technology to create technology-supported pervasive games. In this paper we report on our experiences in transferring the successful involvement of players in computer games to 'modding' for pervasive games. We present the design process, the enabling tools and two sample games provided in boxes to end users. Finally we discuss how our findings inform the design of 'modding' tools for a pervasive game community of the future.
Keywords: User-centered design; Games and infotainment; Programming tools: Integrated environments; Pervasive computing; Pervasive games; End user programming

Tagging and Tracking

RF-Based Initialisation for Inertial Pedestrian Tracking BIBAKFull-Text 238-255
  Oliver Woodman; Robert Harle
Location information is an important source of context for ubiquitous computing systems. We have previously developed a wearable location system that combines a foot-mounted inertial unit, a detailed building model and a particle filter to locate and track humans in indoor environments. In this paper we present an algorithm in which a map of radio beacon signal strengths is used to solve two of the major problems with the original system: scalability to large environments and uncertainty due to environmental symmetry.
   We show that the algorithm allows the deployment of the system in arbitrarily large buildings, and that uncertainty due to environmental symmetry is reduced. This reduction allows a user to be located after taking an average of 38 steps in a 8725 m² three-storey building, compared with 76 steps in the original system. Finally, we show that radio maps such as those required by the algorithm can be generated quickly and automatically using the wearable location system itself. We demonstrate this by building a radio map for the 8725 m² building in under two and a half hours.
Keywords: Radio; localisation; inertial tracking; particle filters
PL-Tags: Detecting Batteryless Tags through the Power Lines in a Building BIBAKFull-Text 256-273
  Shwetak N. Patel; Erich P. Stuntebeck; Thomas Robertson
We present a system, called PL-Tags, for detecting the presence of batteryless tags in a building or home through the power lines. The excitation (or interrogation) and detection of these tags occurs wirelessly entirely using the powerline infrastructure in a building. The PL-Tags proof-of-concept consists of a single plug-in module that monitors the power line for the presence of these tags when they are excited. A principal advantage of this approach is that it requires very little additional infrastructure to be added to a space, whereas current solutions like RFID require the deployment of readers and antennas for triggering tags. An additional benefit of PL-Tags is that the tags are wirelessly excited using an existing phenomenon over the power line, namely electrical transient pulses that result from the switching of electrical loads over the power line. We show how these energy rich transients, which occur by simply turning on a light switch, fan, television, etc., excite these tags and how they are detected wirelessly over the power line. We contend that the PL-Tag system is another class of potential battery-free approaches researchers can use for building pervasive computing applications that require minimal additional infrastructure.
Keywords: Ubiquitous computing; Pervasive computing; Tagging; Sensing; Sensors; Power lines; Hardware
Geo-fencing: Confining Wi-Fi Coverage to Physical Boundaries BIBAFull-Text 274-290
  Anmol Sheth; Srinivasan Seshan; David Wetherall
We present a means of containing Wi-Fi coverage to physical boundaries that are meaningful to users. We call it geo-fencing. Our approach is based on directional antennas, and our motivation is to provide wireless access and privacy models that are a natural fit with user expectations. To evaluate geo-fencing, we use measurements from an indoor testbed of Wi-Fi nodes and APs with electronically-steerable directional antennas. We find that by combining directionality, power control and coding across multiple APs, we are able to successfully confine Wi-Fi coverage to clients located within target regions of varying shapes and sizes; we can select between nodes located as close as five feet from each other.
Securing RFID Systems by Detecting Tag Cloning BIBAKFull-Text 291-308
  Mikko Lehtonen; Daniel Ostojic; Alexander Ilic; Florian Michahelles
Cloning of RFID tags can lead to financial losses in many commercial RFID applications. There are two general strategies to provide security: prevention and detection. The security community and the RFID chip manufacturers are currently focused on the former by making tags hard to clone. This paper focuses on the latter by investigating a method to pinpoint tags with the same ID. This method is suitable for low-cost tags since it makes use of writing a new random number on the tag's memory every time the tag is scanned. A back-end that issues these numbers detects tag cloning attacks as soon as both the genuine and the cloned tag are scanned. This paper describes the method and presents a mathematical model of the level of security and an implementation based on EPC tags. The results suggest that the method provides a potentially effective way to secure RFID systems against tag cloning.
Keywords: Security; clone detection; low-cost; EPC; RFID

Methods and Tools

Towards Ontology-Based Formal Verification Methods for Context Aware Systems BIBAKFull-Text 309-326
  Hedda Rahel Schmidtke; Woontack Woo
Pervasive computing systems work within, and rely on, a model of the environment they operate in. In this respect, pervasive computing systems differ from other distributed and mobile computing systems, and require new verification methods. A range of methods and tools exist for verifying distributed and mobile concurrent systems, and for checking consistency of ontology-based context models. As a tool for verifying current pervasive computing systems both are not optimal, since the former cover mainly tree-based location models, whereas the latter are not able to address the dynamic aspects of computing systems. We propose to formally describe pervasive computing systems as distributed concurrent systems operating on the background of a mereotopological context model.
Keywords: context modelling; mereotopology; program verification; ontologies
Situvis: A Visual Tool for Modeling a User's Behaviour Patterns in a Pervasive Environment BIBAFull-Text 327-341
  Adrian K. Clear; Ross Shannon; Thomas Holland; Aaron J. Quigley; Simon A. Dobson; Paddy Nixon
One of the key challenges faced when developing context-aware pervasive systems is to capture the set of inputs that we want a system to adapt to. Arbitrarily specifying ranges of sensor values to respond to will lead to incompleteness of the specification, and may also result in conflicts, when multiple incompatible adaptations may be triggered by a single user action. We posit that the ideal approach combines the use of past traces of real, annotated context data with the ability for a system designer or user to go in and interactively modify the specification of the set of inputs a particular adaptation should be responsive to. We introduce Situvis, an interactive visualisation tool we have developed which assists users and developers of context-aware pervasive systems by visually representing the conditions that need to be present for a situation to be triggered in terms of the real-world context that is being recorded, and allows the user to visually inspect these properties, evaluate their correctness, and change them as required. This tool provides the means to understand the scope of any adaptation defined in the system, and intuitively resolve conflicts inherent in the specification.
Methodologies for Continuous Cellular Tower Data Analysis BIBAFull-Text 342-353
  Nathan Eagle; John A. Quinn; Aaron Clauset
This paper presents novel methodologies for the analysis of continuous cellular tower data from 215 randomly sampled subjects in a major urban city. We demonstrate the potential of existing community detection methodologies to identify salient locations based on the network generated by tower transitions. The tower groupings from these unsupervised clustering techniques are subsequently validated using data from Bluetooth beacons placed in the homes of the subjects. We then use these inferred locations as states within several dynamic Bayesian networks (DBNs) to predict dwell times within locations and each subject's subsequent movements with over 90% accuracy. We also introduce the X-Factor model, a DBN with a latent variable corresponding to abnormal behavior. By calculating the entropy of the learned X-Factor model parameters, we find there are individuals across demographics who have a wide range of routine in their daily behavior. We conclude with a description of extensions for this model, such as incorporating contextual and temporal variables already being logged by the phones.

The Importance of Context

"It's Just Easier with the Phone" -- A Diary Study of Internet Access from Cell Phones BIBAFull-Text 354-371
  Stina Nylander; Terés Lundquist; Andreas Brännström; Bo Karlson
We conducted a diary study of how 19 experienced users accessed the Internet from cell phones. Our data show that participants often chose the cell phone to access the Internet even though they had access to a computer, and the most common location for Internet access being the home. Reasons for choosing the phone over the computer were speed, convenience and a desire to use the phone for fun. Additionally, the phone is kept close and is always on which makes it convenient to use. The traditional motivation for mobile services "finding out something about where you are" only accounts for 15% of the user activity.
Does Context Matter? -- A Quantitative Evaluation in a Real World Maintenance Scenario BIBAFull-Text 372-389
  Kai S. Kunze; Florian Wagner; Ersun Kartal; Ernesto Morales Kluge; Paul Lukowicz
We describe a systematic, quantitative study of the benefits using context recognition (specifically task tracking) for a wearable maintenance assistance system. A key objective of the work is to do the evaluation in an environment that is as close as possible to a real world setting. To this end, we use actual maintenance tasks on a complex piece of machinery at an industrial site. Subjects for our study are active Zeiss technicians who have an average of 10 years job experience.
   In a within subject Wizard of Oz study with the interaction modality as the independent variable we compare three interaction modalities: (1) paper based documentation (2) speech controlled head mounted display (HMD) documentation, and context assisted HMD documentation. The study shows that the paper documentation is 50% and the speech only controlled system 30% slower then context. The statistical significance of 99% and 95% respectively (one sided ANOVA test). We also present results of two questionnaires (custom design and standard NASA TLX) that show a clear majority of subjects considered context to be beneficial in one way or the other. At the same time, the questionnaires reveal a certain level of uneasiness with the new modality.
On the Anonymity of Home/Work Location Pairs BIBAFull-Text 390-397
  Philippe Golle; Kurt Partridge
Many applications benefit from user location data, but location data raises privacy concerns. Anonymization can protect privacy, but identities can sometimes be inferred from supposedly anonymous data. This paper studies a new attack on the anonymity of location data. We show that if the approximate locations of an individual's home and workplace can both be deduced from a location trace, then the median size of the individual's anonymity set in the U.S. working population is 1, 21 and 34,980, for locations known at the granularity of a census block, census track and county respectively. The location data of people who live and work in different regions can be re-identified even more easily. Our results show that the threat of re-identification for location data is much greater when the individual's home and work locations can both be deduced from the data. To preserve anonymity, we offer guidance for obfuscating location traces before they are disclosed.
Working Overtime: Patterns of Smartphone and PC Usage in the Day of an Information Worker BIBAKFull-Text 398-405
  Amy K. Karlson; Brian Meyers; Andy Jacobs; Paul Johns; Shaun K. Kane
Research has demonstrated that information workers often manage several different computing devices in an effort to balance convenience, mobility, input efficiency, and content readability throughout their day. The high portability of the mobile phone has made it an increasingly valuable member of this ecosystem of devices. To understand how future technologies might better support productivity tasks as people transition between devices, we examined the mobile phone and PC usage patterns of sixteen information workers across several weeks. Our data logs, together with follow-up interview feedback from four of the participants, confirm that the phone is highly leveraged for digital information needs beyond calls and SMS, but suggest that these users do not currently traverse the device boundary within a given task.
Keywords: Mobile information work; multiple devices; cross-device interfaces