Pervasive 2004

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Full Papers and Technotes


 WEDNESDAY April 21, 11:00 - 12:30
 Activity Recognition From User-Annotated Acceleration Data
   Ling Bao, Massachusetts Institute of Technology, United States; Stephen S. Intille, Massachusetts Institute of Technology, United States;  
  Abstract. In this work, algorithms are developed and evaluated to detect physical activities from data acquired using five small biaxial accelerometers worn simultaneously on different parts of the body. Acceleration data was collected from 20 subjects without researcher supervision or observation. Subjects were asked to perform a sequence of everyday tasks but not told specifically where or how to do them. Mean, energy, frequency-domain entropy, and correlation of acceleration data was calculated and several classifiers using these features were tested. Decision tree classifiers showed the best performance recognizing everyday activities with an overall accuracy rate of 84%. The results show that although some activities are recognized well with subject-independent training data, others appear to require subject-specific training data. The results suggest that multiple accelerometers aid in recognition because conjunctions in acceleration feature values can effectively discriminate many activities. With just two biaxial accelerometers thigh and wrist the recognition performance dropped only slightly. This is the first work to investigate performance of recognition algorithms with multiple, wire-free accelerometers on 20 activities using datasets annotated by the subjects themselves.
 Recognizing Workshop Activity Using Body Worn Microphones and Accelerometers
   Paul Lukowicz, Wearable Computing Laboratory, ETH Zürich, Switzerland; Jamie A Ward, Wearable Computing Laboratory, ETH Zürich, Switzerland; Holger Junker, Wearable Computing Laboratory, ETH Zürich, Switzerland; Mathias Stäger, Wearable Computing Laboratory, ETH Zürich, Switzerland; Gerhard Tröster, Wearable Computing Laboratory, ETH Zürich, Switzerland; Thad Starner, College of Computing, Georgia Institute of Technology, United States; Amin Atrash, College of Computing, Georgia Institute of Technology, United States;  
  Abstract. The paper presents a technique to automatically track the progress maintenance or assembly tasks using body worn sensors. The technique is based a novel way of combining data from accelerometers with simple frequency matching sound classification. This includes the intensity analysis of signals from microphones at different body locations to correlate environmental sounds with user activity. To evaluate our method we apply it to activities in a wood shop. On a simulated assembly task our system can successfully segment and identify most shop activities in a continuous data stream with zero false positives and 84.4% accuracy.
 "Are You With Me?" - Using Accelerometers to Determine if Two Devices are Carried by the Same Person
   Jonathan Lester, Department of Electrical Engineering, University of Washington United States; Blake Hannaford, Department of Electrical Engineering, University of Washington; Gaetano Borriello, Department of Computer Science and Engineering, University of Washington, Intel Research Seattle, United States;  
  Abstract. As the proliferation of pervasive and ubiquitous computing devices continues, users will carry more devices. Without the ability for these devices to unobtrusively interact with one another, the user’s attention will be spent on coordinating, rather than using, these devices. We present a method to determine if two devices are carried by the same person, by analyzing walking data recorded by low-cost MEMS accelerometers using the coherence function, a measure of linear correlation in the frequency domain. We also show that these low-cost sensors perform similarly to more expensive accelerometers for the frequency range of human motion, 0 to 10Hz. We also present results from a large test group illustrating the algorithm’s robustness and its ability to withstand real world time delays, crucial for wireless technologies like Bluetooth and 802.11. We present results that show that our technique is 100% accurate using a sliding window of 8 seconds of data when the devices are carried in the same location on the body, is tolerant to inter-device communication latencies, and requires little communication bandwidth. In addition we present results for when devices are carried on different parts of the body.

 
 
 WEDNESDAY April 21, 16:00 - 17:30
 Context Cube: Flexible and Effective Manipulation of Sensed Context Data
   Lonnie Harvel, School of Electrical and Computer Engineering, College of Computing & GVU Center Georgia Institute of Technology, United States; Ling Liu, College of Computing & GVU Center Georgia Institute of Technology, United States; Gregory D. Abowd, College of Computing & GVU Center Georgia Institute of Technology, United States; Yu-Xi Lim, School of Electrical and Computer Engineering, Georgia Institute of Technology, United States; Chris Scheibe, School of Electrical and Computer Engineering, College of Computing & GVU Center Georgia Institute of Technology, United States; Chris Chatham, School of Electrical and Computer Engineering, College of Computing & GVU Center Georgia Institute of Technology, United States;  
  Abstract. In an effort to support the development of context-aware applications that use archived sensor data, we introduce the concept of the Context Cube based on techniques of data warehousing and data mining. Our implementation of the Context Cube provides a system that supports a multi-dimensional model of context data and with tools for accessing, interpreting and aggregating that data by using concept relationships defined within the real context of the application. We define the Context Cube information model, demonstrate functional applications that we have developed with the system, and explore possible applications that may be developed more easily using our tool.
  A Context-Aware Communication Platform for Smart Objects
   Frank Siegemund, Institute for Pervasive Computing Department of Computer Science ETH Zurich, Switzerland;  
  Abstract. When smart objects participate in context-aware applica- tions, changes in their real-world environment can have a signi¯cant im- pact on underlying networking structures. This paper presents a commu- nication platform for smart objects that takes an object's current real- world context into account and adapts networking structures accordingly. The platform provides (1) mechanisms for specifying and implement- ing context-aware communication services, (2) a tuplespace-based com- munication abstraction for inter-object collaboration, and (3) support for linking communication and context-recognition layers. For specifying context-aware communication services, a high-level description language, called SICL, and a compiler that generates corresponding code for smart objects were realized. The tuplespace-based infrastructure layer for inter- object collaboration hides low-level communication issues from higher layers and facilitates collaborative context recognition between cooper- ating objects. The paper also presents examples of context-aware com- munication services and evaluates the platform on the basis of a concrete implementation on an embedded device platform.
 Siren: Context-aware Computing for Firefighting
   Xiaodong Jiang, Computer Science Division University of California, Berkeley, United States; Nicholas Y. Chen, Computer Science Division University of California, Berkeley, United States; Kevin Wang, Computer Science Division University of California, Berkeley, United States; Leila Takayama, Department of Communication Stanford University United States; James A. Landay, DUB Group, Computer Science and Engineering University of Washington, United States;  
  Abstract. Based on an extensive field study of current firefighting practices, we have developed a system called Siren to support tacit communication between firefighters with multiple levels of redundancy in both communication and user alerts. Siren provides a foundation for gathering, integrating, and distributing contextual data, such as location and temperature. It also simplifies the development of firefighting applications using a peer-to-peer network of embedded devices through a uniform programming interface based on the information space abstraction. As a proof of concept, we have developed a prototype context- aware messaging application in the firefighting domain. We have evaluated this application with firefighters and they have found it to be useful for improving many aspects of their current work practices.

 
 
 THURSDAY April 22, 10:00 - 11:00
 Spectacle-Based Design of Wearable See-Through Display for Accommodation-Free Viewing
   Marc von Waldkirch, Wearable Computing Lab, ETH Zurich, Switzerland; Paul Lukowicz, Wearable Computing Lab, ETH Zurich, Switzerland; Gerhard Tröster, Wearable Computing Lab, ETH Zurich, Switzerland;  
  Abstract. This paper presents the design and the evaluation of a novel wearable see-through display which provides imaging being nearly independent from the eye's accommodation. This means, that the overlaid display data are perceived to be in-focus independent of the distance the eye is focusing at, making the see-through mode much more convenient in use. The display is based on the direct projection of a miniature LCD onto the user's retina in combination with the use of partially coherent light to further improve the display's defocusing properties. The paper discusses the display concept and presents various experimental results for verification. Finally, a compact and lightweight design for an unobtrusive integration into normal spectacles is proposed.
  A Compact Battery-less Information Terminal for Real World Interaction
   Takuichi Nishimura, Cyber Assist Research Center, National Institute of Advanced Industrial Science and Technology, Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Japan; Hideo Itoh, Cyber Assist Research Center, National Institute of Advanced Industrial Science and Technology, Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, School of Information Science, Japan Advanced Institute of Science and Technology; Yoshiyuki Nakamura, Cyber Assist Research Center, National Institute of Advanced Industrial Science and Technology, Japan; Yoshinobu Yamamoto, Cyber Assist Research Center, National Institute of Advanced Industrial Science and Technology, Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Japan; Hideyuki Nakashima Cyber Assist Research Center, National Institute of Advanced Industrial Science and Technology, Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, School of Information Science, Japan Advanced Institute of Science and Technology;  
  Abstract. A ubiquitous computing environment is intended to support users in their search for necessary information and services in a situationdependent form. This paper proposes a location-based information support system using a Compact Battery-less Information Terminal (Co- BIT) to support users interactively. A CoBIT can communicate with the environmental system and with the user using only energy supplied from the environmental system and the user. The environmental system has functions to detect the terminal position and direction to realize situational support. This paper newly shows detailed characteristics of information download and upload using the CoBIT system. And it also describes various types of CoBITs and their usage in museums and event shows.

 
 
 THURSDAY April 22, 11:30 - 12:30
 INCA: A Software Infrastructure to Facilitate the Construction and Evolution of Ubiquitous Capture & Access Applications
   Khai N. Truong, Georgia Institute of Technology College of Computing & GVU Center, United States; Gregory D. Abowd, Georgia Institute of Technology College of Computing & GVU Center, United States;  
  Abstract. People’s daily lives provide them with memories and records that they often want to review later. They must expend time and effort to record these experiences manually for future retrieval. To address this issue, applications that automatically capture details of a live experience and provide future access to that experience have become an increasingly common theme of research in ubiquitous computing. In this paper, we present our experience building a number of capture and access applications, sharing insights on the successes and difficulties we encountered. These lessons inform the design of the INCA toolkit (Infrastructure for Capture and Access), which supports the construction of applications in this class. We will demonstrate how INCA facilitates the rapid prototyping and simplified evolution of increasingly complex capture and access applications.

 
 
 THURSDAY April 22, 14:00 - 15:30
 Activity Recognition in the Home Using Simple and Ubiquitous Sensors
   Emmanuel Munguia Tapia, Massachusetts Institute of Technology United States; Stephen S. Intille, Massachusetts Institute of Technology United States; Kent Larson, Massachusetts Institute of Technology United States;  
  Abstract. In this work, a system for recognizing activities in the home setting using a set of small and simple state-change sensors is introduced. The sensors are designed to be "tape on and forget" devices that can be quickly and ubiquitously installed in home environments. The proposed sensing system presents an alternative to sensors that are sometimes perceived as invasive, such as cameras and microphones. Unlike prior work, the system has been deployed in multiple residential environments with non-researcher occupants. Preliminary results on a small dataset show that it is possible to recognize activities of interest to medical professionals such as toileting, bathing, and grooming with detection accuracies ranging from 25% to 89% depending on the evaluation criteria used.
  Automatic Calibration of Body Worn Acceleration Sensors
   Paul Lukowicz, Institute for Computer Systems and Networks, UMIT Innsbruck, Austria, Wearable Computing Lab, ETH Zurich, Switzerland; Holger Junker, Wearable Computing Lab, ETH Zurich, Switzerland; Gerhard Tröster, Wearable Computing Lab, ETH Zurich, Switzerland;  
  Abstract. The paper presents a scheme for automatic calibration of body worn acceleration sensors which does not require any user interaction and any knowledge about the position and orientation of the sensors on the body. We describe the theoretical principle behind the method, discuss the main practical implementation concerns, and present experimental validation results.
  Reject-optional LVQ-based Two-level Classifier to Improve Reliability in Footstep Identification
   Jaakko Suutala, Intelligent Systems Group, Infotech Oulu, Finland; Susanna Pirttikangas, Intelligent Systems Group, Infotech Oulu, Finland; Jukka Riekki, Intelligent Systems Group, Infotech Oulu, Finland; Juha Röning, Intelligent Systems Group, Infotech Oulu, Finland;  
  Abstract. This paper reports experiments of recognizing walkers based on measurements with a pressure-sensitive EMFi-floor. Identification is based on a twolevel classifier system. The first level performs Learning Vector Quantization (LVQ) with a reject option to identify or to reject a single footstep. The second level classifies or rejects a sequence of three consecutive identified footsteps based on the knowledge from the first level. The system was able to reduce classi- fication error compared to a single footstep classifier without a reject option. The results show a 90% overall success rate with a 20% rejection rate, identifying eleven walkers, which can be considered very reliable.
 Issues with RFID usage in ubiquitous computing applications
   Christian Floerkemeier, Institute for Pervasive Computing Department of Computer Science ETH Zurich, Switzerland; Matthias Lampe, Institute for Pervasive Computing Department of Computer Science ETH Zurich, Switzerland;  
  Abstract. Radio Frequency Identification (RFID) has recently received a lot of attention as an augmentation technology in the ubiquitous computing domain. In this paper we present various sources of error in passive RFID systems, which can make the reliable operation of RFID augmented applications a challenge. To illustrate these sources of error, we equipped playing cards with RFID tags and measured the performance of the RFID system during the different stages of a typical card game. The paper also shows how appropriate system design can help to deal with the imperfections associated with RFID.

 
 
 THURSDAY April 22, 16:00 - 17:00
  A Fault-tolerant Key-Distribution Scheme for Securing Wireless Ad-hoc Networks
   Arno Wacker, Institute for Parallel and Distributed Systems (IPVS) Universität Stuttgart, Germany; Timo Heiber, Institute for Parallel and Distributed Systems (IPVS) Universität Stuttgart, Germany; Holger Cermann, Institute for Parallel and Distributed Systems (IPVS) Universität Stuttgart, Germany; Pedro Jos Marron, Institute for Parallel and Distributed Systems (IPVS) Universität Stuttgart, Germany;  
  Abstract. We propose a novel solution for securing wireless ad-hoc networks. Our goal is to provide secure key exchange in the presence of device failures and denial-of-service attacks. The proposed solution relies solely on symmetric cryptography and therefore is applicable for highly resource-limited devices. In order to avoid a single point of trust, no master device or base station is used. We achieve this by enhancing our previously published approach with redundancy and algorithms for recovery on device failures.
  ProxNet: Secure DynamicWireless Connection by Proximity Sensing
   Jun Rekimoto, Interaction Laboratory, Sony Computer Science Laboratories, Inc, Japan; Takashi Miyaki, Interaction Laboratory, Sony Computer Science Laboratories, Inc, Japan; Michimune Kohno, Interaction Laboratory, Sony Computer Science Laboratories, Inc, Japan;  
  Abstract. This paper describes a method for establishing ad hoc and infrastructuremode wireless network connections based on physical proximity. Users can easily establish secure wireless connections between two digital devices by putting them in close proximity to each other and pressing the connection button. The devices "identify" each other by measuring each other's signal strength. We designed a set of protocols to support secure connections between digital devices by using a proximity communication mode to exchange session keys.We also introduce a "dummy point" that is analogous to a wireless access point but handles proximity-mode communication. The dummy point represents physical locations of digital devices and supports context-sensitive network communications.
 Tackling Security and Privacy Issues in Radio Frequency Identification Devices
   Dirk Henrici, University of Kaiserslautern, Department of Computer Science, Germany; Paul Müller, University of Kaiserslautern, Department of Computer Science, Germany;  
  Abstract. This paper introduces shortly into the security and privacy issues of RFID systems and presents a simple approach to greatly enhance location privacy by changing traceable identifiers securely on every read attempt. The scheme gets by with only a single, unreliable message exchange. By employing one-way hash functions the scheme is safe from many security threats. It is intended for use in item identification but is useful in other applications as well.

 
 
 FRIDAY April 23, 09:00 - 10:30
  Towards Wearable Autonomous Microsystems
   Nagendra B. Bharatula, Wearable Computing Laboratory ETH Zurich, Switzerland; Stijn Ossevoort, Wearable Computing Laboratory ETH Zurich, Switzerland; Mathias Stäger, Wearable Computing Laboratory ETH Zurich, Switzerland; Gerhard Tröster, Wearable Computing Laboratory ETH Zurich, Switzerland;  
  Abstract. This paper presents our work towards a wearable autonomous microsystem for context recognition. The design process needs to take into account the properties ofa wearable environment in terms of sensor placement for data extraction, energy harvesting, comfort and easy integration into clothes and accessories. We suggest to encapsulate the system in an embroidery or a button. The study ofa microsystem consisting ofa light sensor, a microphone, an accelerometer, a microprocessor and a RF transceiver shows that it is feasible to integrate such a system in a button-like form of 12 mm diameter and 4 mm thickness. We discuss packaging and assembly aspects ofsu ch a system. Additionally, we argue that a solar cell on top ofthe button - together with a lithium polymer battery as energy storage - is capable to power the system even for a user who works predominantly indoors.
 Ubiquitous Chip: a Rule-based I/O Control Device for Ubiquitous Computing
   Tsutomu Terada, Graduate School of Information Science and Technology, Osaka University, Japan; Masahiko Tsukamoto, Graduate School of Information Science and Technology, Osaka University, Japan; Keisuke Hayakawa, Internet System Research Laboratories, NEC Corp., Japan; Tomoki Yoshihisa, Graduate School of Information Science and Technology, Osaka University, Japan; Yasue Kishino, Graduate School of Information Science and Technology, Osaka University, Japan; Atsushi Kashitani, Internet System Research Laboratories, NEC Corp., Japan; Shojiro Nishio Graduate School of Information Science and Technology, Osaka University, Japan;  
  Abstract. In this paper, we propose a new framework for ubiquitous computing by rule-based, event-driven I/O (input/output) control devices. Our approach is flexible and autonomous because it employs a behavior-description language based on ECA (Event, Condition, Action) rules with simple I/O control functions. We have implemented a prototype ubiquitous device with connectors and several sensors to show the effectiveness of our approach.
  eSeal - A System for Enhanced Electronic Assertion of Authenticity and Integrity
   Christian Decker, Telecooperation Office (TecO), University of Karlsruhe, Germany; Michael Beigl, Telecooperation Office (TecO), University of Karlsruhe, Germany; Albert Krohn, Telecooperation Office (TecO), University of Karlsruhe, Germany; Philip Robinson, Telecooperation Office (TecO), University of Karlsruhe, Germany; Uwe Kubach, SAP AG, Corporate Research Germany;  
  Abstract. Ensuring authenticity and integrity are important tasks when dealing with goods. While in the past seal wax was used to ensure the integrity, electronic devices are now able to take over this functionality and provide better, more fine grained, more automated and more secure supervision. This paper presents eSeal, a system with a computational device at its core that can be attached to a good, services in the network and a communication protocol. The system is able to control various kinds of integrity settings and to notify authenticated instances about consequent violations of integrity. The system works without infrastructure so that goods can be supervised that are only accessible in certain locations. The paper motivates the eSeal system and its design decisions, lists several types of integrity scenarios, presents the communication protocol and identifies practical conditions for design and implementation. An implementation in a business relevant scenario is presented as a proof of concept.

 
 
 FRIDAY April 23, 11:00 - 12:30
  A Distributed Precision Based Localization Algorithm for Ad-Hoc Networks
   Leon Evers, EEMCS Faculty, University of Twente, the Netherlands; Stefan Dulman, EEMCS Faculty, University of Twente, Ambient Systems, the Netherlands; Paul Havinga, EEMCS Faculty, University of Twente, Ambient Systems, the Netherlands;  
  Abstract. In this paper we introduce a new distributed algorithm for location discovery. It can be used in wireless ad-hoc sensor networks that are equipped with means of measuring the distances between the nodes (like the intensity of the received signal strength). The algorithm takes the reliability of measurements into account during calculation of the nodes positions. Simulation results are presented, showing the algorithms performance in relation to its accuracy, communication and calculation costs. The simulation results of our approach yield 2 to 4 times better results in position accuracy than other systems described previously. This level of performance can be reached using only few broadcast messages with small and constant size, for each node in the network.
  Adaptive On-device Location Recognition
   Kari Laasonen, Basic Research Unit, Helsinki Institute for Information Technology Department of Computer Science, University of Helsinki, Finland; Mika Raento, Basic Research Unit, Helsinki Institute for Information Technology Department of Computer Science, University of Helsinki, Finland; Hannu Toivonen, Basic Research Unit, Helsinki Institute for Information Technology Department of Computer Science, University of Helsinki, Finland;  
  Abstract. Location-awareness is useful for mobile and pervasive computing. We present a novel adaptive framework for recognizing personally important locations in cellular networks, implementable on a mobile device and usable, e.g., in a presence service. In comparison, most previous work has used service infrastructure for location recognition and the few adaptive frameworks presented have used coordinate-based data. We construct a conceptual framework for the tasks of learning important locations and predicting the next location. We give algorithms for endcient approximation of the ideal concepts, and evaluate them experimentally with real data.
  Accommodating Transient Connectivity in Ad Hoc and Mobile Settings
   Radu Handorean, Department of Computer Science and Engineering Washington University in St. Louis, United States; Christopher Gill, Department of Computer Science and Engineering Washington University in St. Louis, United States; Gruia-Catalin Roman, Department of Computer Science and Engineering Washington University in St. Louis, United States;  
  Abstract. Much of the work on networking and communications is based on the premise that components interact in one of two ways: either they are connected via a stable wired or wireless network, or they make use of persistent storage repositories accessible to the communicating parties. A new generation of networks raises serious questions about the validity of these fundamental assumptions. In mobile ad hoc wireless networks connections are transient and availability of persistent storage is rare. This paper is concerned with achieving communication among mobile devices that may never find themselves in direct or indirect contact with each other at any point in time. A unique feature of our contribution is the idea of exploiting information associated with the motion and availability profiles of the devices making up the ad hoc network. This is the starting point for an investigation into a range of possible solutions whose essential features are controlled by the manner in which motion profiles are acquired and the extent to which such knowledge is available across an ad hoc network.

 
 
 FRIDAY April 23, 14:00 - 15:30
 Microbiology Tray and Pipette Tracking as a Proactive Tangible User Interface
   Harlan Hile, University of Washington, United States; Jiwon Kim, University of Washington, Intel Research Seattle, United States; Gaetano Borriello, University of Washington, Intel Research Seattle, United States;  
  Abstract. Many work environments can bene t from integrated com- puting devices to provide information to users, record users' actions, and prompt users about the next steps to take in a procedure. We focus on the cell biology laboratory, where previous work on the Labscape project has provided a framework to organize experiment plans and store data. Currently developed sensor systems allow amount and type of materi- als used in experiments to be recorded. This paper focuses on providing the last piece: determining where the materials are deposited. Using a camera and projector setup over a lab bench, vision techniques allow a specially marked well tray and pipette to be located in real time with enough precision to determine which well the pipette tip is over. Us- ing the projector, the tray can be augmented with relevant information, such as the next operation to be performed, or the contents of the tray. Without changing the biologist's work practice, it is possible to record the physical interactions and provide easily available status and advice to the user. Preliminary user feedback suggests this system would indeed be a useful addition to the laboratory environment.
 Augmenting Collections of Everyday Objects: A Case Study of Clothes Hangers as an Information Display
   Tara Matthews, EECS Department, University of California, Berkeley, United States; Hans-W. Gellersen, Computing Department, Lancaster University; Kristof Van Laerhoven, Computing Department, Lancaster University; Anind K. Dey, Intel Research Berkeley, Intel Corporation;  
  Abstract. Though the common conception of human-computer interfaces is one of screens and keyboards, the emergence of ubiquitous computing envisions interfaces that will spread from the desktop into our environments. This gives rise to the development of novel interaction devices and the augmentation of common everyday objects to serve as interfaces between the physical and the virtual. Previous work has provided exemplars of such everyday objects augmented with interactive behaviour. We propose that richer opportunities arise when collections of everyday objects are considered as substrate for interfaces. In an initial case study we have taken clothes hangers as an example and augmented them to collectively function as an information display.
 MirrorSpace: using proximity as an interface to video-mediated communication
   Nicolas Roussel, Laboratoire de Recherche en Informatique & INRIA Futurs, Universit Paris-Sud XI, France; Helen Evans, Laboratoire de Recherche en Informatique & INRIA Futurs, Universit Paris-Sud XI, France; Heiko Hansen, Laboratoire de Recherche en Informatique & INRIA Futurs, Universit Paris-Sud XI, France;  
  Abstract. Physical proximity to other people is a form of non-verbal communication that we all employ everyday, although we are barely aware of it. Yet, existing systems for video-mediated communication fail to fully take into account these proxemics aspects of communication. In this note, we present MirrorSpace, a video communication system that uses proximity as an interface to provide smooth transitions between peripheral awareness and very close and intimate forms of communication.
 SearchLight - A Lightweight Search Function for Pervasive Environments
   Andreas Butz, Department of Computer Science, Saarland University, Germany; Michael Schneider, Department of Computer Science, Saarland University, Germany; Mira Spassova, Department of Computer Science, Saarland University, Germany;  
  Abstract. We present a lightweight search function for physical objects in instrumented environments. Objects are tagged with optical markers which are scanned by a steerable camera and projector unit on the ceil- ing. The same projector can then highlight the objects when given the corresponding marker ID. The process is very robust regarding calibra- tion, and no 3D model of the environment is needed. We discuss the scenario of ¯nding books in a library or o±ce environment and several extensions currently under development.
Pervasive 2004      April 18-23      Linz / Vienna, Austria      Back to Top