The proliferation of mobile computing devices and local-area wireless networks has fostered a growing interest in location-aware systems and services. In this paper we present RADAR, a radio-frequency (RF)-based system for locating and tracking users inside buildings. RADAR operates by recording and processing signal strength information at multiple base stations positioned to provide overlapping coverage in the area of interest. It combines empirical measurements with signal propagation modeling to determine user location and thereby enable location-aware services and applications. We present experimental results that demonstrate the ability of RADAR to estimate user location with a high degree of accuracy.

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RADAR: an in-building RF-based user location and tracking system

This paper surveys the field of augmented reality AR, in which 3D virtual objects are integrated into a 3D real environment in real time. It describes the medical, manufacturing, visualization, path planning, entertainment, and military applications that have been explored. This paper describes the characteristics of augmented reality systems, including a detailed discussion of the tradeoffs between optical and video blending approaches. Registration and sensing errors are two of the biggest problems in building effective augmented reality systems, so this paper summarizes current efforts to overcome these problems. Future directions and areas requiring further research are discussed. This survey provides a starting point for anyone interested in researching or using augmented reality.

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A survey of augmented reality

Humans perceive the three-dimensional structure of the world with apparent ease. However, despite all of the recent advances in computer vision research, the dream of having a computer interpret an image at the same level as a two-year old remains elusive. Why is computer vision such a challenging problem and what is the current state of the art? Computer Vision: Algorithms and Applications explores the variety of techniques commonly used to analyze and interpret images. It also describes challenging real-world applications where vision is being successfully used, both for specialized applications such as medical imaging, and for fun, consumer-level tasks such as image editing and stitching, which students can apply to their own personal photos and videos. More than just a source of recipes, this exceptionally authoritative and comprehensive textbook/reference also takes a scientific approach to basic vision problems, formulating physical models of the imaging process before inverting them to produce descriptions of a scene. These problems are also analyzed using statistical models and solved using rigorous engineering techniques Topics and features: structured to support active curricula and project-oriented courses, with tips in the Introduction for using the book in a variety of customized courses; presents exercises at the end of each chapter with a heavy emphasis on testing algorithms and containing numerous suggestions for small mid-term projects; provides additional material and more detailed mathematical topics in the Appendices, which cover linear algebra, numerical techniques, and Bayesian estimation theory; suggests additional reading at the end of each chapter, including the latest research in each sub-field, in addition to a full Bibliography at the end of the book; supplies supplementary course material for students at the associated website, http://szeliski.org/Book/. Suitable for an upper-level undergraduate or graduate-level course in computer science or engineering, this textbook focuses on basic techniques that work under real-world conditions and encourages students to push their creative boundaries. Its design and exposition also make it eminently suitable as a unique reference to the fundamental techniques and current research literature in computer vision.

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Computer Vision: Algorithms and Applications

Instrumenting the physical world through large networks of wireless sensor nodes, particularly for applications like environmental monitoring of water and soil, requires that these nodes be very small, lightweight, untethered, and unobtrusive. The problem of localization, that is, determining where a given node is physically located in a network, is a challenging one, and yet extremely crucial for many of these applications. Practical considerations such as the small size, form factor, cost and power constraints of nodes preclude the reliance on GPS of all nodes in these networks. We review localization techniques and evaluate the effectiveness of a very simple connectivity metric method for localization in outdoor environments that makes use of the inherent RF communications capabilities of these devices. A fixed number of reference points in the network with overlapping regions of coverage transmit periodic beacon signals. Nodes use a simple connectivity metric, which is more robust to environmental vagaries, to infer proximity to a given subset of these reference points. Nodes localize themselves to the centroid of their proximate reference points. The accuracy of localization is then dependent on the separation distance between two-adjacent reference points and the transmission range of these reference points. Initial experimental results show that the accuracy for 90 percent of our data points is within one-third of the separation distance. However, future work is needed to extend the technique to more cluttered environments.

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GPS-less low-cost outdoor localization for very small devices

In 1997, Azuma published a survey on augmented reality (AR). Our goal is to complement, rather than replace, the original survey by presenting representative examples of the new advances. We refer one to the original survey for descriptions of potential applications (such as medical visualization, maintenance and repair of complex equipment, annotation, and path planning); summaries of AR system characteristics (such as the advantages and disadvantages of optical and video approaches to blending virtual and real, problems in display focus and contrast, and system portability); and an introduction to the crucial problem of registration, including sources of registration error and error-reduction strategies.

https://www.cc.gatech.edu/~blair/papers/ARsurveyCGA.pdf

Recent advances in augmented reality

In some examples, a three dimensional display system includes a display (for example, a display screen or a display panel), a micro lens array, and an eye tracker to track one or more eyes of a person and to provide eye location information. The display system also includes a rendering processor to render or capture color plus depth images (for example, RGB-D images) or light field images. The display system also includes a light field processor to use the eye location information to convert the rendered color plus depth images or light field images to display images to be provided to the display.

Three dimensional glasses free light field display using eye location

Raytheon's TACEC (Terminal Area Capacity Enhancement Concept) proposes to increase airspace capacity by using closely-spaced formations of arriving and departing aircraft to greatly increase airport capacities. However, a blunder in a tightly-spaced formation could cause a collision with another aircraft or its wake vortices. Therefore, humans need tools and visualization aids to detect and respond to blunders. This paper is the first in a series of experiments to evaluate the ability of different visualization modes to enable detection of lateral blunders. We tested four viewpoints, one warning aid, and three blunder speeds in a within-subjects design. This study had twelve participants. The main result was that changing the viewpoint made a large difference; the cockpit view was by far the worst. Blunder detection varied by speed and was difficult in the presence of noise. Future experiments should use more realistic simulators and pilots as participants. Language: en

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Evaluating Visualization Modes for Closely-Spaced Parallel Approaches

There are currently two primary ways of viewing location specific information in-situ on hand-held mobile device screens: using a see-through augmented reality interface and using a touch-based interface with panoramas. The two approaches use fundamentally different interaction metaphors: an AR-style of interacting where the user holds up the device and physically moves it to change views of the world, and a touch-based technique where panorama navigation is independent of the physical world. We have investigated how this difference in interaction technique impacts a user's spatial understanding of the mixed reality world. Our study found that AR-style interaction provided better spatial understanding overall, while touch-based interaction changed the experience to have more similar characteristics to interaction in a separate virtual environment.

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Comparing spatial understanding between touch-based and AR-style interaction

We demonstrate ThinVR as a new approach to simultaneously address the bulk and limited FOV of today’s head-worn VR displays. ThinVR enables a VR display to provide 180 degrees horizontal FOV in a thin, compact form factor. Our approach is to replace traditional large optics with a curved microlens array of custom-designed heterogeneous lenslets and place these in front of a curved display. Custom-designed heterogeneous optics were crucial to make this approach work, since over a wide FOV, many lenslets are viewed off the central axis. We show the viability of the ThinVR approach through two demonstrations, using both dynamic and static displays.

ThinVR: VR displays with wide FOV in a compact form factor

In one example, a method for displaying three dimensional images can include generating a three dimensional image. The method can also include detecting a field of view of a user based on a position and orientation of the head of the user. The method can also include separating the three dimensional image into a plurality of frames based on the field of view of the user, wherein each frame corresponds to one of a plurality of display panels. Furthermore, the method can include modifying the plurality of frames based on a depth of each pixel in the three dimensional image. Additionally, the method can include displaying the three dimensional image using the plurality of display panels.

Ronald Azuma

Papers

Three dimensional glasses free light field display using eye location

Evaluating Visualization Modes for Closely-Spaced Parallel Approaches

Comparing spatial understanding between touch-based and AR-style interaction

ThinVR: VR displays with wide FOV in a compact form factor

Three dimensional image display