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From: Rohit Khare (
Date: Tue Jan 25 2000 - 20:26:56 PST

[An academic citation to no less than our own W.J. Mattson! --RK]

>The most basic view of WorldBoard is simply as a spatially
>addressable bulletin board, containing geocoded (longitude, latitude, and
>elevation) messages or Web pages. It is important to note that this view of
>WorldBoard is much simpler than an operational augmented reality system. For
>example, people might access information on a WorldBoard through a traditional
>Web browser on a desktop machine, perhaps using a map to spatially navigate to
>the place.

 From the paper by Spohrer... also remember:

>(FCC) regulation E911 requires
>all cellular phone manufacturers to provide a mechanism for locating
>on which the emergency number 911 is dialed to within about 100
>meters, no later
>than October 1, 2001. In some regions over 30 percent of all 911
>calls are made
>on mobile phones, and this percentage is on the rise.
WorldBoard is a powerful new information and communication technology
being developed and promoted by the WorldBoard Forum. At its most
basic level, WorldBoard enables people to associate Web objects with
a PLACE-Proximity and Location to Access Contextual Enlightenment.
This enhancement of the Web enables anyone to virtually attach
information, tools and serrvices to any location on the planet or,
using an identification tag, to objects or people in the environment.
These specific physical objects (i.e., a specific car or a box of
cereal) or each instance of a class of objects (i.e., any oak tree or
any 1999 Honda Accord LX Coupe with black exterior) may carry
information with them as they move about the physical world.

The basic WorldBoard system requires no new hardware
infrastructure.It runs on current Internet servers and devices. The
system includes: a markup language based on XML (WorldBoard XML) and
WorldBoard Metadata; WorldBoard server add-on modules for enhancing
existing Web servers; WorldBoard Search Engines, WorldBoard Portals,
and WorldBoard Viewers running on various hardware platforms. The FAQ
has more information available.

The WorldBoard concept was originated at Apple Computer in the
Learning Communities group. In 1996, Jim Spohrer wrote a paper called
WorldBoard as part of his work on a National Science Foundation
funded project seeking to visualize next generation learning
environments. The original concept describes a globabl bulletin board
system in which the planet is used as a virtual bulletin board for
digital content. The ultimate system utilized augmented reality
eyewear so that people interact with and perceive information in new

Marty Siegel, Sonny Kirkley, and Elizabeth Boling at Indiana
University we intrigued with the idea and offered the first course on
WorldBoard in the Fall of 1997. The students in this course developed
mockups and visualizations of how people would utilize such a system.
By the Fall of 1998, Sonny took over the course and began to focus on
building the global infrastructure needed for such a system. This was
the foundation of the technology being developed for WorldBoard. The
MUSE and WILD projects were established during this time.

In the Spring of 1999 the WorldBoard Forum was established as an
informal network of people interested in WorldBoard. While most of
the work done on the standards has been at Indiana University, others
joined the forum to express their interest, share information and to
collaborate on future development. There were two Websites created,
the WorldBoard.Org site for general information on WorldBoard and the
WorldBoard Education Object Economy (EOE) as a community space for
the Forum members. Several projects were formed at that time
including applications in retail settings with handheld shopping
tools. Demonstration versions of these tools were exhibited at the
International Mass Retail Association conference in Orlando.
IBM Systems Journal Vol 38, No. 4 - Pervasive Computing
0018-8670/99/$5.00 (C) 1999 IBM

Information in places

by J. C. Spohrer

As global positioning, wireless communication, and mobile display technologies
continue to advance, our notion of place will change. Information
geocoded signs and later animated special effects--will begin to populate real
physical space on what we call WorldBoard channels. WorldBoard is a proposed
global infrastructure to associate information with places and ultimately to
provide people with enhanced information perception services. This
paper explores
the notion of a WorldBoard from four perspectives: historical background,
technical feasibility, potential applications, and social implications. Recent
developments, ranging from lower-cost Global Positioning System
(GPS)-enabled car
navigation systems to Casio Electronics' first-of-a-kind GPS-enabled
foreshadow increased availability of location-aware information services and
products. While significant technical, application development, and social
challenges remain before a complete WorldBoard infrastructure can be made
broadly, uniformly, and cost-effectively available, some feasible first steps
toward this important goal are recommended. Finally, a notion like WorldBoard
offers an opportunity to reflect on how technological possibilities unfold.

What if we could put information in places? More precisely, what if we could
associate relevant information with a place and perceive the
information as if it
were really there? WorldBoard is a vision of doing just that on a
planetary scale
and as a natural part of everyday life. For example, imagine being
able to enter
an airport and see a virtual red carpet leading you right to your gate, look at
the ground and see property lines or underground buried cables, walk along a
nature trail and see virtual signs near plants and rocks, or simply look at the
night sky and see the outlines of the constellations. (See Figure 1.)

Since the pioneering work of Ivan Sutherland in 1968[1], the vision of putting
information in places has been a key goal of researchers developing augmented
reality systems.[2] Unlike virtual reality systems[3] that allow users to
experience a completely virtual or simulated world, augmented reality systems
allow users to experience a mixed reality that combines virtual objects with
real-world objects. Video special effects, as seen in commercials, television
programs, and movies, offer a glimpse at some of the possibilities when
artificial images can be seamlessly combined with real images--for
example, cars
that seem to dissolve before one's eyes offering cut-away views, or animated
characters in the kitchen encouraging kids to eat their breakfast. Unlike video
special effects, augmented reality systems support the perception of
real special
effects--or special effects happening right where a person is in real
time and in
real space. For example, imagine a person walking into a parking lot
and looking
at a car while wearing special eyeglasses, or looking through the
viewfinder of a
special video camera, who is then able to see a cut-away view of the
car exposing
the complete exhaust system perfectly aligned with the real car. That person is
perceiving a real special effect or experiencing augmented reality.

In a 1992 paper, Warren Robinett describes some of the ways that augmented
reality can be used to extend human perception, beyond the more familiar ways
that devices like the telescope and microscope extend human perception.[4] The
primary difference, of course, is that devices like the telescope and
show us only what is actually there, whereas augmented reality systems can
superimpose useful information drawn from any aspect of human culture or
imagination. For example, the constellations are both physical
reality (position
of stars) and human invention (mythology projected onto the heavens).
For another
example, a telescope can help us see pinpoints of light circling
Jupiter, but an
augmented reality system can allow us to perceive the moons with
their projected
orbits, names of the moons and other useful information, whether or not Jupiter
is above or below the horizon, and whether or not it is daytime or
nighttime. How
might electronic expansion of human perception change our relationship to the
world and to information about the world?

The science of human perception, the technology of augmented reality,
the art of
special effects, and the culture of the information age come together to enable
WorldBoard and potentially change our notion of place. A stable notion of place
has been fundamental to the way we live our lives;[5,6] we build
mental models of
objects in spatial array around us in places; we go to places to do routine
things; we put things in places for reasons; different individuals or
organizations control what can and cannot be done in a place or put in a place;
we all control some limited number of places and expect that things we put in
those places will be there for us. WorldBoard, if it can be made broadly,
uniformly, and cost-effectively available, changes our notion of place in some
fundamental ways. First, a new conceptual category of thing (nonphysical
information) can now seemingly be in a place. Second, since
information takes up
no real physical space, the same place can appear differently
depending on who is
perceiving it and for what purpose (i.e., by tuning to a different WorldBoard
channel). Third, many of the most useful properties of a place, such as its
history, can be stored with the place.

To explore the implications of WorldBoard as it relates to putting
information in
its place, this paper is structured around six questions:

1. Initial concept: What is the basic idea behind WorldBoard?
2. Historical background: What have the pioneers achieved?
3. Technical feasibility: Can it really be done?
4. Potential applications: Will it be truly useful?
5. Social implications: Will it catch on?
6. Reflections: Are we even close in our thinking?

Initial concept

Even though the utility of associating information with places goes beyond
education, educational users are often very tolerant of experimental
infrastructures (witness the evolution of the Internet). Hence, the education
community was identified as a good initial audience and codevelopment
partner for
WorldBoard. With the education community in mind, three key design goals and a
four-step development plan were created as part of the original WorldBoard
effort. The purpose was to get a simple operational infrastructure in
place that
would evolve over time. The first stage of WorldBoard development would not
require technologies that support a complete augmented reality system.

WorldBoard was originally conceived as a planetary chalkboard for
twenty-first-century learners, allowing them to post and read
messages associated
with any place on the planet. In the mid-1990s, WorldBoard was seen as the
logical culmination of an effort to improve educational tools--cognitive tools,
social tools, and perception tools. As part of a National Science Foundation
(NSF)-funded project, a consortium of industry, university, and government
organizations began an investigation aimed at improving the quality and
availability of educational software.[7-13] In the course of that effort, three
kinds of technology were developed: authoring tools to more easily create
educational software content, on-line learning communities to exchange and
improve the content, and new paradigms in mobile computing to support
learning in

More generally, the view at that time was that the quality and availability of
educational materials could be improved if people were empowered with cognitive
tools to create educational materials, social tools to collaboratively improve
the educational materials, and perception tools to access the educational
materials in context.

For example, a student might write a report about the life cycle of
frogs, create
a simulation of the life cycle using an authoring tool, and display the report
and simulation on a Web site inviting others to comment and link to the report.
On a series of field trips to a real frog pond, a student might use a digital
camera to take pictures to add to the report, as well as use a
hand-held computer
to gather sensor data about water and air temperature. In this example, content
creation, collaborations, and conversations, as well as authentic
contexts, were
seen as part of a more complete learning experience than traditional classroom
lectures. Pointers to much of this earlier work can be found at the Educational
Object Exchange Web site (, maintained by an educational
research, nonprofit organization that is carrying on one thread of this earlier

Design goals. The early WorldBoard effort adopted three key design
goals: (1) to
be operational (at least partially) on a planetary scale from the start, (2) to
be able to improve rapidly as technology advances, and (3) to be so simple and
useful that people use it in everyday life.

First, for a variety of reasons, the decision was made that some initially
realistic accuracy level (to within 1 meter) for planetary
positioning should be
selected. An imaginary 1-meter cube provides six faces (up, down, north, south,
east, and west) to post and access information. A 10-meter cube would be larger
than most rooms and much larger than many objects of interest in daily life.
However, a 10-meter scale is easy to navigate on high-resolution
satellite images
or aerial photographs, and is an achievable accuracy level for certain
positioning devices. Just for reference, the Global Positioning
System (GPS) can
be used to provide 20- to 100-meter accuracy quite reliably in most outdoor
settings.[14] A differential GPS can improve this by an order of magnitude to
provide 2- to 10-meter accuracy quite reliably in areas where differential
services are available.[15] Therefore, either additional positioning
or manual interfaces are required to allow a person to navigate to
any particular
1-meter cube.

The information on a square-meter face might be organized to look like
information on a poster or bulletin board (i.e., pictures, documents, URL
references). Because many people might want to post messages to the
same place or
restrict access to posted information, the notion of password-protected
WorldBoard channels was introduced. Positioning was to be accomplished either
manually (using a map or other interface to select a particular cube
for writing
or reading information), or automatically (using a location-aware
device). Manual
positioning would allow people to post and retrieve messages from another
location, while automatic positioning with location-aware devices
requires their
physical presence. For example, in anticipation of an upcoming field trip to a
national park, a student might use a browser to navigate to the park, and then
leave programmatic commands at various locations to gather data on temperature,
light, and humidity. Later, when the student is exploring the park,
the student's
location-aware hand-held computer would automatically collect the
desired data as
the student moved to those locations, time- and space-stamping the
data as well.
Furthermore, a teacher could post audio reminders to be triggered when students
approach certain locations. For example, when students cross a bridge
they could
receive a short voice note, or a page call, to look upstream and see the
waterfall that exposes particular geological formations being studied by the
class, or as a warning to be very careful as they are entering a
fragile ecology
zone of the park.

A cubic meter may sound like an ad hoc way to divide up space, and it certainly
is (though a similar coordinate system will be described in a later section).
This was intended to be a somewhat challenging, but not altogether unrealistic,
starting point. If learners equipped with WorldBoard browser-based tools and
location-aware devices could write and read multimedia messages posted anywhere
on the planet, they could use the cubic-meter space like posters for a science
fair project. One way to move away from this overly simple model is
to recognize
that where natural surfaces (buildings or rocks) or other objects
(appliances or
trees) exist, additional methods of associating information with the places are

Nevertheless, the simple cubic-meter model did allow for a kind of
zooming in and
out. For example, a user might project all of the information from
adjacent cubes
onto a larger cube (10-meter view or 100-meter view). This could be
valuable for
looking for a particular kind of information within a certain radius. One could
even imagine using the size of a message as an indication of its
importance. For
example, children might leave a ten-mile-square message floating above the city
skyline for their parents, or a much smaller note that appears to be on the
surface of a desk or a window in an office.

A second key design goal has been to allow WorldBoard to improve rapidly as
underlying technologies advance. For example, as positioning
technology improves,
users can post information to smaller spaces more accurately. Ultimately, as
decimeter, centimeter, and better accuracy is reliably achieved for both indoor
and outdoor locations, users will be able to set the color of a
particular cubic
centimeter in space. Voxels, or volumetric pixels, allow users to create
LEGO**/Logo-like objects in places. Furthermore, as display
technology improves,
rather than seeing two-dimensional information posted to the faces of
cubes on a
hand-held computer, a user might use stereoscopic display glasses to
see complete
three-dimensional (3D) views of the information created out of voxels
or rendered
in other ways. However, before these techniques become commonplace,
content could be made available to be viewed via hand-held computer
displays with
meter-level positioning accuracy.

A third key design goal has been to keep the initial WorldBoard
design simple, so
that people might get started even before mobile location-aware devices become
widely available. The most basic view of WorldBoard is simply as a spatially
addressable bulletin board, containing geocoded (longitude, latitude, and
elevation) messages or Web pages. It is important to note that this view of
WorldBoard is much simpler than an operational augmented reality system. For
example, people might access information on a WorldBoard through a traditional
Web browser on a desktop machine, perhaps using a map to spatially navigate to
the place. Once a user has navigated to a location, the user might
view close-up
photographs of that location (up, down, north, south, east, west), and use
standard graphical tools to mark up the image, outlining objects of interest,
adding arrows or other graphics, and posting messages or even pieces
of software
that run when location-aware devices get to that location and trigger
the code. A
public WorldBoard channel might allow people to ask questions and
post answers to
a particular location ("What is the name of the plant located
here?"); a private
WorldBoard channel might provide high-quality geological or biological
information, or perhaps even advertising with the potential of
providing services
that go beyond existing billboards. Getting started with projects like these is
straightforward. For example, the Confluence Project[16] is one of many efforts
to collect a sampling of geocoded photographs of specific longitude
and latitude
points from around the world.

Development plan. The original WorldBoard proposal described a four-stage
development plan:

1. WorldBoard servers: First, identify a reasonable way to associate
with places on a planetary scale. Given coordinates for one of the
six faces of a
meter cube, a channel number, and a password, the server could serve up a Web
page to the client. This information would be authored and accessed
from existing
Web browsers.

2. WorldBoard clients: Second, identify a mobile capability to author
and access
the information associated with places on a planetary scale. A location-aware
device with navigation, authoring, and global wireless communication
would be needed--probably, a device with camera and pen input, and either a
manual map interface or an automatic differential GPS for positioning.

3. WorldBoard glasses: Third, make use of positioning and display advances to
create the illusion of seeing (and more generally perceiving) information in
places. In addition to the basic client capability, by using kinematic GPS for
subcentimeter orientation platform capabilities, glasses (or
palm-sized monocles)
could be used to display information objects coregistered with reality, rather
than simply appearing on a cube face.

4. WorldBoard services: Fourth, make use of new organizations to provide
education, safety, entertainment, and industry-specific services on spatial
information channels. Organizations might eventually provide archiving, design,
and other associated information services, employing information architects and

As part of the NSF grant, prototypes of various aspects of WorldBoard were
implemented, but the complete vision has yet to be realized. Since the original
proposal was published in 1996, the notion of a WorldBoard has been
evolving and
key technologies have been advancing. For example, today there are even
companies, such as GeoPerception,[17] as well as projects, such as Neighborhood
Web,[18] that have the explicit goal of allowing the Web and other useful
information to be everywhere perceptible. In the next section, some of the
pioneering work on which WorldBoard and related efforts draw is presented.

Historical background: Three threads

The primacy of the physical world is the starting point for much of
the research
discussed in this section. Nevertheless, there is also the belief that
appropriate technology tools can augment human capabilities19 and
thereby enhance
daily life, combining virtual with physical reality. A key part of such
augmentation tools is the display technology--though communication and
positioning technologies are also important and will be highlighted in the next
section. The quest to see electronic information objects in real
physical spaces
has been approached using three types of displays:

1. Head-mounted see-through display glasses (monocular and binocular)
2. Hand-held palm-sized displays that are portholes into information spaces
3. Projectors that superimpose images on the environment or in free space

Using see-through, hand-held, or projector displays, everyday places
and objects
can gain new electronic properties without losing their familiar physical

Head-mounted displays. One of the earliest uses of head-mounted displays was in
1968. Ivan Sutherland published the first paper describing an operational
augmented reality system using a head-mounted display.[1] The fundamental idea
was to present the user with a perspective image that changed as the
user moved.
The system used half-silvered mirrors to allow the user to
simultaneously see the
displayed materials (wire-frame images that appeared on miniature cathode ray
tubes) and real objects in the room. Displayed materials could be
made either to
hang disembodied in space or to coincide with maps, desktops, walls,
or the keys
of a typewriter. Sutherland and his colleagues created both a mechanical
head-position sensor and an ultrasound sensor that were used to track the
location and orientation of the head-mounted display and hence the user's head.
The mechanical head-position sensor was rather large and uncomfortable to use,
but resulted in a sure method to measure head position. The ultrasonic
head-position sensor also measured head position, but after a few minutes its
cumulative errors were objectionable.

While the user's movements were restricted to a region about six feet square, a
far cry from a planetary-scale infrastructure, nevertheless the key concept of
creating the illusion of seeing three-dimensional objects in real space was
achieved. Furthermore, it is interesting to note that one of the images that
Sutherland was working with was a wire-frame "room" that was a simple six-faced
cube with the letters "C," "F," "N," "S," "E," and "W" on the six
faces. As will
be described in the next section, head-mounted display glasses have been
decreasing in size and weight. Already, they have attained the form of normal
prescription reading glasses or sunglasses.

In the 1980s there was a resurgence of interest in head-mounted displays for
virtual reality applications, military heads-up displays for pilots
(e.g., Apache
helicopter pilots), and medical applications for surgeons. In the
1990s, heads-up
display glasses have become a standard component of wearable computers, such as
IBM's VisionPad concept computer.[20] In the next few paragraphs, examples of
these evolving applications of head-mounted displays for augmented reality are
briefly discussed.

In 1991 Ron Azuma[21] and his colleagues at the University of North Carolina at
Chapel Hill first demonstrated to the public, in the Tomorrow's
Realities Gallery
of the ACM SIGGRAPH conference in Las Vegas, a scalable tracking system for
head-mounted displays. The bulk and weight of the displays was still a major
problem, but by using optical sensors mounted on the head unit to
detect infrared
beacons in the ceiling, this group was able to demonstrate substantial
improvement over magnetic trackers[22] widely in use at that time. Azuma points
out that even when the position and orientation of display glasses is
well-known and useful content has been authored for a physical place, there
remains the problem of preserving the illusion that a virtual object
is actually
part of the real world. This requires proper alignment and registration of the
virtual objects to the real world, in spite of user movements, tracking errors,
and a variety of system delays and device latencies. This is a
well-known problem
in movie special effects, but because special effects can be done off line, the
movie special effects task is significantly easier than the demands
of providing
real-time special effects for a mobile augmented-reality experience. Even tiny
errors in alignment and registration are quickly noticeable. This
problem will be
examined in more detail in the next section.

Also in the early 1990s, Feiner and his colleagues at Columbia University[23]
described an office of the future in which a person wears a see-through
head-mounted display to superimpose graphical information on objects in the
office environment. For example, superimposed pictures might let a person see
inside a printer, copier, or filing cabinet to show how to service it or to
locate a document. This prototype augmented-reality system used a Reflection
Technology Private Eye (720 x 280 resolution, red lines, and letters) and a
LogiTech 3D position and orientation tracking system (ultrasonic
transmitters and
receivers). The focus of this work was on the complexity of authoring
presentations for augmented-reality spaces. Like other high-end multimedia and
special-effects productions, this form of information presentation requires
significant skill and time to produce. Feiner demonstrated that knowledge-based
systems could be built to automate the design of presentations that explain how
to perform 3D tasks. KARMA (knowledge-augmented reality for maintenance
assistance) was a test-bed system for automating the design of augmented
realities that explain maintenance and repair tasks. KARMA was based
on Feiner's
IBIS (intent-based illustration system). Feiner also developed a system termed
"architectural anatomy" that allowed a user to "see through" walls and view
wiring, plumbing, and other infrastructure.

More recently, Feiner and his colleagues[24] describe a prototype wearable
augmented-reality system. Their tour-guide application provides
information about
a university campus (i.e., names of buildings and Web information
about academic
departments). This prototype augmented-reality system used an i-O
Display Systems
i-glasses** head-worn display (quarter-VGA-resolution color display) and a
Trimble DSM (direct sequence modulation) GPS receiver with differential
correction services provided by Differential Corrections, Inc. to achieve about
1-meter accuracy. Wireless communication was accomplished with a campus-wide
network of radio base stations and an NCR WaveLAN** radio modem (2 megabits per
second). Hand-held computers, including Apple Newtons**, were also used
experimentally as display devices in this work.

Starner and his colleagues at the Massachusetts Institute of Technology (MIT)
Media Lab[25] describe a wearable augmented-reality system that "tracks the
user's location through computer vision techniques without any off-body
infrastructure." Earlier systems required a beacon architecture, which meant
placing active or passive identifier tags on objects in the physical
In 1995, projects at the MIT Media Lab began binding virtual data to physical
locations to support minitours of the laboratory. The purely computer-vision
approach to position determination described in this most recent work
by Starner
uses hidden Markov model (HMM) techniques. HMM techniques can be used to model
the environment as a set of states with transitions, and then match the camera
input to the model to produce a probability of being in a particular state
(location) of the model (world). This approach to positioning may be especially
useful when combined with inertial sensors, GPS, and other information sources
that can improve the robustness and reliability of tracking information. Also,
noteworthy in this work is the fact that the prototype actually used
two cameras:
one for observing the environment, and a second one for observing the user. In
the case of the Patrol Game (battlefield simulation) application, utilizing the
second camera enabled the computer to be aware of the user's current task and
resource level, thus allowing timely information to be displayed to help the
user. This work illustrates that increases in contextual and user information
taken together can lead to more intelligent and natural user interfaces.

Rekimoto and his colleagues at Sony Corporation[26] describe "a system that
allows users to dynamically attach newly created digital information such as
voice notes or photographs to the physical environment, through wearable
computers as well as normal computers. Similar to the role that Post-it** notes
play in community messaging, we expect our proposed method to be a fundamental
communication platform when wearable computers become commonplace." The display
is based on the Sony Glasstron** (monocular see-through heads-up
display), a CCD
(charge-coupled device) camera, and an infrared sensor. Nortel
Network's NetWave
AirSurfer** is used for wireless communication. This prototype
supports infrared
beacons and visual identification markers as contextual information.
The authors
describe a "time-machine mode" for authoring information to previously visited
remote locations, as well as the ability to send e-mail messages to particular
locations. Additionally, they describe the possibility of using a standard Web
browser to access messages that have been attached to particular locations. In
this way, users can work with normal computers to interact with the information
spaces, as well as the mobile wearable computers to interact with the
in context. The potential utility of virtual notes on restaurants, office
equipment, and other objects in the physical environment is also discussed.
Rekimoto et al. also discuss the use of a hand-held display system called
NaviCam, or a magnifying-glass approach to augmented reality as discussed

Hand-held displays. Two problems with the use of head-mounted displays for
augmented reality applications are: (1) head-mounted displays are still
conspicuous when worn, even when they approximate the form of normal reading
glasses, and (2) users of head-mounted displays sometimes complain of
nausea as a
side effect of prolonged use.[28,29] Hand-held displays with cameras that
superimpose information on the real scene have advantages in certain
Hand-held displays can be stored and brought out only when needed;
more than one
person can look at the display at the same time; the physical appearance may be
more acceptable than glasses; and the nausea effects may be eliminated or less
pronounced. In this section, a few key examples of research efforts that have
used hand-held displays for augmented reality applications are presented.

In the early 1990s as part of the Chameleon project,[30,31] Fitzmaurice and
colleagues developed the notion of spatially aware computers. These
are tools to
perceive electronic information in "a world where electronic information will
ultimately be everywhere." The goal of this effort was to look for ways of
associating electronic information with physical objects in the
environment. The
information would then be viewed, not on a large fixed display on a
desk, but on
a small, mobile display that would act as a window (porthole) into the
information space. The hand-held computer and display needed both spatial
awareness and physical environment sensing capabilities in order to create the
illusion of merging the electronic and physical worlds. Different information
could be presented to the user depending on the orientation of the hand-held
unit. For example, weather information, travel itineraries, and geographical
points of interest might be easily accessed. In addition, a user could attach a
voice annotation to a selected object. To remind the user of the
presence of the
voice annotation, a graphical note was superimposed on the video data.

In order to avoid being flooded and overwhelmed with the sheer quantity of
electronic information that might eventually be everywhere, they proposed the
need to adopt the notion of situated information spaces. The electronic
information associated with physical objects could be associated and collocated
with those objects. The physical objects anchor the information, providing hot
spots and retrieval cues for the user. Fitzmaurice's team also introduced the
notion of mediator objects that act as interfaces between the physical and
computational environments. For example, when a whiteboard acts as an
mediator, notes made on the hand-held unit can automatically be transferred and
appear on the electronic whiteboard.

Instead of viewing and manipulating a computerized world through a large
stationary computer and display, Fitzmaurice and colleagues proposed
to shift to
a new model in which people carry around a very small hand-held computer that
acts as a personal display of information spaces. The displays are
aware of their
surroundings and change depending on the situation in which they are immersed.
However, it is interesting to note that their prototype actually used a camera
pointed at a large workstation monitor; the video was then fed into a small
hand-held unit. An Ascension Bird** six-degree-of-freedom input device was
attached to a small display (from Casio Electronics) to provide reasonably
responsive (50 millisecond delay) position, translation, and rotation
information, but only within a three-foot cube range (about the same
usable area
as Sutherland's system).

In the mid-1990s, Abowd[32,33] and his colleagues at Georgia Institute of
Technology worked with context-aware hand-held computers in a project known as
CyberGuide. Apple Newtons and other hand-held computers detected
infrared signals
from beacons in the ceiling to provide information about particular
locations in
a room. In one scenario, visitors were each given a CyberGuide unit and could
walk around a demo room to get information about all of the projects
on display.
The Smithsonian Institution has used a similar system for traveling shows, but
instead of automatically detecting their location, users must enter a number
associated with a particular display of interest.

Projector displays. Besides head-mounted displays and hand-held devices with
cameras, a third technique for combining and aligning real and
virtual objects is
to project information onto real-world surfaces. While this approach has clear
limitations (projectors are not very portable, require lots of power, and most
real-world surfaces do not make particularly good projection screens),
nevertheless it has been explored for applications where a wall or desktop
surface is the primary focus of attention for mixed reality interactions.

Early experiments projecting information onto surfaces (using
projection displays
and reading information from the environment using cameras) were performed by
Myron Krueger in 1969. Krueger[34] reasoned that interfaces should know about
people and the environment (both user-aware and context-aware, as in
the Starner
work previously cited). He created environmental technology systems known as
VideoDesk, VideoTouch, and VideoPlace. Much of Krueger's work was the
of a new medium for human-computer interaction. Other researchers focused on
using the technique to accomplish office automation tasks or achieve levels of
fidelity with corresponding real-world alternatives, for ex-ample Knowlton,[35]
Schmandt,[36] Wellner,[37-39] and MacKay.[40] Wellner and his research team
created a system known as the DigitalDesk that used electronic ink and
superimposed images on paper documents on a desktop. However, Wellner
and others
note that paper is easier to read than most computer screens today;
it is cheap,
universally accepted, tactile, and portable, and use of paper is
growing about 20
percent annually.[41] Most recently, Raskar[42] described spatially augmented
reality (SAR), where virtual objects are rendered directly within or on the
user's physical space. Raskar's work explores the benefits that derive when
several individuals can interact with the information at the same time. Other
related uses of projection displays in creating 3D information environments are
the RWAV (Room With A View) system[43] and the CAVE** (Cave Automatic Virtual
Environment) system.[44]

While the projection techniques seem inherently limited today as a means of
creating a global infrastructure for information in places, they are worth at
least a passing mention for two reasons. First, glasses and hand-held
devices are
primarily for personal use, whereas projection tends to be used to
promote social
interactions and communications. Second, projection techniques can be used to
simulate environments in which any and all surfaces can potentially act like a
display. Many trade-offs exist in designing augmented-reality
experiences, and an
exploration of alternative display technologies helps crystallize some of the
issues. For example, while socially sharing an augmented-reality experience may
be important in some situations (projection display), there may be other times
when individuals in a group wish to have distinct augmented reality experiences
in the same place at the same time (head-mounted or hand-held displays).

Technical feasibility

The technical feasibility of WorldBoard can be evaluated with respect to the
four-step development plan originally proposed (see the previous section). In
this section, each step in the development plan is introduced, along
with issues
(including some nontechnical issues), followed by a more detailed discussion of
the technical feasibility issues. Five key aspects of WorldBoard
feasibility are:
positioning technology, communication technology, display technology,
simple user
experience, and critical mass of geocoded content. In the case of WorldBoard
services and geocoded content, both largely economic issues, there is the
technical issue of how to rapidly bootstrap content and make it easily

WorldBoard servers: Geospatial portals. The first stage of WorldBoard requires
the creation of Web sites or portals that allow people to easily associate
information with places on a planetary scale. Given a global coordinate for a
specific cubic meter--one of the six faces of the meter cube, a channel
identification, and a password--the Web site should serve up a Web page to the
client. This information should be authorable and accessible from existing Web

Creating this stage of WorldBoard will require a substantial effort,
although it
is technically feasible. The issues include: What is the global
coordinate system
that is used to address cubic meters? What is the user experience for authoring
and accessing information? What are the basic applications available to users
through their browsers? How much storage is required? How are
multiple servers to
be networked together to provide a seamless user experience?

The UTM (Universal Traverse Mercator) coordinate system is used
around the world
for topographical maps, with northing and easting offsets expressed in 1-meter
units.[45] In addition, UTM is a worldwide grid of 1200 zones: 60
6-degree zones
extending eastward from the International Date Line, and 10 8-degree
zones above
and 10 below the equator. Although UTM is not currently usable in polar regions
(the edge of a zone nearer the pole is shorter than the edge further from the
pole, as the pole is a point of convergence), extensions have been proposed.

The first questions users may have are: Where am I in UTM coordinate space? How
can I see what has been posted to a particular place? What if I am off by a few
meters? How can I post something to a particular place? Unfortunately, without
location-aware devices accurate to the cubic meter, answering the "where am I"
question is quite a bit of work. First, we consider three
less-than-friendly user
experiences, and then a more ideal proposal.

Three possible user experiences are: (1) "drill down" on satellite
maps or other
maps that have been annotated with UTM coordinates (and then make careful
measurements off observable points); this is possible with Microsoft's
TerraServer**, 46 (2) enter a mailing address or telephone number and then look
up UTM coordinates given to some local landmark that have previously
been entered
into a database (and then make careful measurements off the
observable landmark),
or (3) settle for less than meter-level accuracy, or make up ad hoc relative
coordinates from some local landmark.

None of these seems particularly appealing or likely to catch on. However,
consider two points: (1) for certain applications, this level of accuracy is
already routine and therefore available--archaeological digs, property surveys,
building construction, geographic information systems for roads and public
utilities, and (2) for many applications, this level of accuracy
really does not
matter or only matters with respect to a local coordinate space whose global
coordinates can safely float or be tied to an arbitrary point until further
refinement is needed. The user experience becomes much easier in many ways if
only 100-meter accuracy is required. However, while this may be suitable for
certain applications, it too easily sidesteps important issues that must be
addressed if WorldBoard is ever to become a truly user-friendly technology that
is simple to use and useful in everyday life.

A more ideal user experience would be to either fly down smoothly to a location
(as opposed to progressively drilling and waiting, as on current systems) or,
after entering an address or location, be placed at a standard entry point to
that location and be able to move through the space in a mode compatible with
that space. For example, this is how many 3D virtual environment games work
today, but rather than fictional worlds a very accurate model of the real world
could be used. In today's 3D games, the user appears as an avatar in a virtual
world, and the mode of transportation is on foot, in a vehicle, or in an
airplane. Moving a pointing device and a throttle (or rate
controller), the user
is comfortably able to move through the space to any number of
locations. Many of
these game engines are freely available on the Web; some even include
the source
code and tools to build custom worlds.[47] Again, freely available tools bring
the possibility of bootstrapping WorldBoard by working with the education
community--a project for children around the world could be to build
3D models of
their communities with meter-level accuracy. Governments could give
an excellent
starting point by providing a topographically accurate foundation based on
satellite images that would have rough terrain features included. By mapping
textures from aerial images on regions, or directly using pictures of
the outside
of buildings and roads for textures, quite recognizable models of the
world could
be created in a straightforward manner. Some efforts with this goal are already
underway, such as the Virtual L.A. project, which is creating a meter-level
accuracy 3D model of the entire Los Angeles basin.[48]

Of course, the Virtual L.A. model and others like it will be
incomplete, in part,
because some spaces are private, although this changes over time.[49] For
example, if a house is for sale, and there is an "open house" sales
event, people
are allowed to roam freely, but once the house is sold, unless one is
invited in,
the space is private. This does raise a social acceptance issue: who wants to
have the floor plan of their home as part of a public interface to a spatial
information store? David Gelernter's notion of Mirror Worlds[50] includes
dynamically updated models of the world, and of Mirror Worlds he
says: "Its goal
is merely to convert the theoretically public into the actually
public. What was
always available in principle merely becomes available in fact."

With a 3D world-view-interface, users could quickly navigate to where
they are or
where they want to be to post or read information. By pressing a key
and making a
selection, the 1-meter-cube grids could be quickly overlayed on the world view
and users could post to the faces of the cubes. Alternatively, users could post
information directly to the surfaces of walls in buildings or the
ground outside.

The basic tools that users (as producers and consumers) would need are: 3D
world-touring tools, 3D world-construction tools, tools to post messages (Web
pages) to any of the six faces of cubic-meter grid overlayed on the
world, tools
to see information that is available in a region, at different scales (zoom in
and zoom out) and sorted by creation date, who posted the information, and
keyword searches, etc.

The storage requirements for WorldBoard user experience are a function of the
fidelity desired. If simple, coarse-wire frames are used, the storage is quite
modest. Modeling a typical city block or suburban neighborhood might require on
the order of 1 megabyte to allow someone familiar with the area to navigate;
adding some simple textures and details might require about 10 megabytes.
However, if numerous unique textures are used and submeter detail is provided,
the storage requirements can quickly soar to a gigabyte or more. A sense of the
current response rate for these types of models when accessed through a Web
browser can be experienced by visiting vendor Web sites.[51,52]

The problem of networking multiple servers together to provide a seamless user
experience is also challenging. Ideally, anyone should be able to set up a
WorldBoard server. However, everyone's WorldBoard servers should be able to
interoperate in a manner that provides a consistent user experience. If some
organization or individual sets up a WorldBoard server it is either
to provide a
place for others to post and access geocoded information, or to
deliver geocoded
information to a wide audience. A service provider must first make available to
users a channel identification, which could be a URL, or literally a channel
number or name, assuming that registration organizations are set up. Next the
service provider must make available to users a model (3D world-view interface)
of the space to be navigated, though a user may prefer a different
model, raising
an interoperability issue. And finally, the service provider must
provide useful
content that is stored, or more likely, dynamically updated on the WorldBoard
cubes, directly attached to a 3D model, or in some other way
available for users.
To improve the response time, users may choose to cache much of this on their
local systems and only receive small packets that update geospatial regions of

WorldBoard clients: Mobile and location-aware. The second stage of WorldBoard
requires the development of mobile ways to author and access information
associated with places on a planetary scale. The simplest version of the client
would be a mobile wireless Web browser with a manual interface for
positioning. A
more complete client would be location-aware, using appropriate automatic
positioning technology, such as GPS.

Again, the issues are numerous, but overall an interesting initial subset of
WorldBoard client functionality is technically feasible. Issues
include: Can the
necessary functionality be packaged in a small, lightweight, mobile device that
has adequate battery life, processing power, and storage capacity to be viable?
What is the coverage area of the wireless communication, bandwidth, cost, and
communication standard employed? What is the coverage area of the positioning
technology, its accuracy and ability to produce orientation as well as location
data, and the rate of position updates?

Packaging the necessary functionality for a mobile WorldBoard client
is very near
at hand.[53] Already, a number of interesting devices exist with subsets of
WorldBoard client functionality:[54-57]

1. Magellan Corporation's GSC 100** product, the first hand-held
global satellite
communicator, can send and receive e-mail anywhere in the world, and
built-in GPS
allows the e-mail messages to be geocoded. The device is 8 by 3.5 by
1.75 inches
and can store about 100 messages.

2. Garmin International's NavTalk** product combines a mobile cell phone with a
GPS receiver and includes map displays. Calling another NavTalk phone shows the
position of the person being called on the map.

3. Nokia's 7110 product combines a mobile cell phone and hand-held PC with
wireless Web browsing capabilities.

4. 3Com Corporation's PalmPilot** PC has add-ons that can provide GPS
and mapping
software. For example, DeLorme's Earthmate** GPS receiver using the Solus**
Promapping application can download multiple maps and routing
directions from an
on-line server, Street Atlas USA** 6.0, Topo USA**, or AAA Map'n'Go**.[58]

Currently, these devices have limited display resolution (text and simple
graphics), limited battery life (less than a day or two at most for very heavy
usage), and limited and expensive bandwidth (kilobytes per second
that cost up to
several cents per second). Nevertheless, portable color game machines and
videophones are appearing that may soon support interfaces similar to the
proposed 3D world-view interface for WorldBoard.[59-61] For WorldBoard park and
museum tours, local storage similar to game machines or portable CD or DVD
(digital video disk) players are also a possibility.

Wireless communication capability for the WorldBoard clients could make use of
cellular and satellite telephone systems. The primary issues are coverage area,
bandwidth, and cost. The demand for cellular telephones in the United States,
Europe, and Japan is driving the creation of extensive infrastructure, and
competition is beginning to lower costs, though lack of global communication
standards limits progress. Overcoming these limits, satellite communication
systems for consumers, such as Iridium LLC's 66-satellite network, provide
excellent global coverage, but at a cost (about $3000 for a telephone
and upwards
of $1.79 per minute at voice bandwidths) and size disadvantage.[62]
Also, Orbital
Sciences Corporation is shipping the Magellan GSC 100 product
mentioned earlier.
For short-range wireless communication at higher, less expensive
bandwidths, many
solutions exist,[63] and Bluetooth[64] is emerging as a very
short-range wireless
communication standard for information appliances. Overall, industry
analysts are
predicting a "Moore's Law" of bandwidth, in which prices are halved every 18
months due to the efforts of carriers such as Frontier Corporation, IXC
Communications, Level 3 Communications, Qwest Communications International, and
The Williams Companies.[65]

GPS is likely to be the core positioning technology for WorldBoard clients,
because of both its global scope and plummeting costs. For this reason, it is
worthwhile to understand GPS strengths and limitations in depth. Leick[66] has
written a technical introduction to the Global Positioning System and satellite
surveying. A summary is included in the Appendix.

Commercial GPS systems are produced by several established
as well as an increasing number of innovative start-up companies.[70-72] To
improve the accuracy of GPS products, DGPS (differential GPS) services are also
broadly available in the United States.[15] For even greater accuracy,
ground-based stations (pseudolites) can be used as in the Trimble 7400MSi GPS
receiver, which provides real-time kinematic, centimeter-accurate position
updates computed five times a second with latency of 2/10ths of a second.[67]

For some applications, alternative positioning techniques are
preferred or can be
used in conjunction with GPS. Especially indoors, GPS alternatives have been
used, including: local beacons and vision recognition,[25] textured light
sources,[73] ultrasonics,[74] and accelerometers.[75] Ultrasonic positioning
technologies, based on triangulation using timing, phase shift, and signal
strength data along with other techniques, can provide accuracies of about 5
centimeters in areas of about 10 square meters. Accelerometers provide
information about acceleration, and by integrating twice, position can be
estimated (acceleration |P8 time = velocity, velocity |P8 time =
distance). Each
integration adds errors, and without resetting, the errors eventually become so
large that the position estimate is no longer accurate.[76] Inertial navigation
systems (INSs) used in cars are based on accelerometers, and solve the error
reset problem by relying on turns in the road and accurate maps. A
very accurate
positioning system that relies on no off-body infrastructure should be possible
by combining suitably accurate accelerometers with binocular vision systems to
reset errors. As will be discussed in the next section, the binocular vision
systems can also provide the information needed to accurately align virtual
objects with images of the world, creating real-time/space special effects.

WorldBoard glasses: Overlays. The third stage of WorldBoard is to use
advances in
positioning, display, and special effects (computer graphics) to create the
illusion of seeing (and more generally perceiving) information in places. The
hand-held PC with a camera is one of the simplest devices with the
capability to
display information objects coregistered with reality (that is to overlay and
align virtual objects to create the illusion of persistence when an observer
moves around). However, eyeglasses that could be worn almost all the time would
have the advantage of providing a long-term sustained illusion of
seeing virtual
objects in the world, if negative physiological side-effects of
today's heads-up
displays (HUDs) can be overcome. Cameras could be supplemented with additional
sensors to provide increased awareness of the environment.

For hand-held devices and glasses, what resolution, brightness, and environment
illumination matching are required to make overlayed images convincing? Can the
nausea effects often associated with heads-up displays be overcome
with improved
speeds, resolutions, and understanding of the human perception system? Can worn
displays be made suitably stylish and socially acceptable? Other than a camera,
what additional environment-sensing capabilities might be needed or
useful? What
will the user experience be like to have motion artifacts, obstructions, and
other unexpected changes in the physical environment? How will object
identification and relative spatial coordinates be handled for overlaying
information on mobile objects?

The original WorldBoard prototype used Virtual i-O's i-glasses, and
provided only
a quarter VGA color image in a somewhat bulky headset.[77] MicroOptical
Corporation has introduced a display with the same resolution but in
a form that
is much closer to normal reading glasses.[78] Microvision is working on the
Virtual Retinal Display** technology, which projects images directly onto the
human retina and has potential advantages for achieving high-resolution image
requirements for realistic augmented reality.[79] Other companies, including
Displaytech,[80] Sony Electronics,[81] and IBM,[20] have introduced miniature
displays. There has even been progress on creating a bionic retina that can be
used to restore sight to the blind.[82] Of course, hand-held displays with
built-in cameras are also advancing rapidly, and are quite suitable, and even
preferred, for many applications.[60,61]

While the form factors and resolution of mobile display technology
are improving
rapidly, one of the key challenges is the software that can combine real and
virtual images into a realistic composite. This is an especially
challenging task
as the user moves around, since a tracker must be accurate to a small
fraction of
a degree in orientation and a few millimeters in position; otherwise
the illusion
of a virtual object in the real world will be destroyed. Azuma[21] suggests the
following demonstration to understand the problem: "Take out a dime and hold it
at arm's length. The diameter of the dime covers approximately 1.5 degrees of
arc. In comparison a full moon covers .5 degrees of arc. Now imagine a virtual
coffee cup sitting on a real table 2 meters away from you. An angular error of
1.5 degrees in head orientation moves the cup 52 millimeters. Clearly, a small
orientation error could result in a cup suspended in midair." Or even more
simply, close your left eye, and hold a finger very near your right
eye to block
out some object in the room. Moving your head even the slightest
amount (or even
a slight vibration of your finger) causes objects at the edge of your finger to
be eclipsed. Even very small positioning or orientation errors will cause a
noticeable jittering of virtual images overlayed on real objects. Additional
sources of error include latency in the tracker and graphics
software, which show
up when the head is moving rapidly (up to 300 degrees per second).
New algorithms
to improve the speed and quality of coregistration of an augmented
reality image
are being developed, and this is an active area of research.[83,84]
The two main
approaches are feature-based and global image techniques.[85] Feature-based
approaches use recognizable beacons in a scene for registration, whereas global
image techniques process all pixels in an image using optical flow or other

While a discussion of the physiology of the eye and the psychological sensation
of sight are beyond the scope of this paper, the absolute limit of resolution,
assuming an individual rod or cone is the limit, is between 0.3 and 0.5 minutes
of arc[86] for human perception. For glasses with a 1.5-inch lens that covers
about 120 degrees of arc, this translates to an upper bound on resolution of
about 10 000 dots per inch (dpi). A more realistic lower bound is based on the
fact that most readers can perceive improvements in printed font
quality on paper
only up to about 600 dpi. Even if displays achieve these resolutions with
adequate brightness, the psychology of binocular sight creates a host of
additional challenges. Stereopsis, lighting conditions, and motion effects all
contribute to the psychological sensation of sight, and deviations from our
expectations about the relationship of perceived images to reality
can result in
difficulty with focusing and a sensation of nausea.[29] Fortunately, there are
many useful applications for WorldBoard prior to complete solutions for the
visual overlay and coregistration problems.

WorldBoard services. The fourth step in the WorldBoard development plan, though
it will be going on in parallel with all the others, is to involve existing and
new organizations to provide education, safety, entertainment, and
industry-specific services on geospatial information channels. New
might eventually provide archiving, design, and other associated WorldBoard
information services, employing information architects and designers.

Issues include: What are the standards and protocols for combining GPS and the
Internet? Who will pay for the creation of geocoded content? What will the role
of consumers, businesses, governments, and new organizations be? What
will users'
experience be in dealing with many WorldBoard information channels?

WorldBoard cannot succeed without geocoded content or, more simply,
content that
has been spatially tagged with descriptors as to where it will be
useful. It took
years for a critical mass of HTML (HyperText Markup Language) content on HTTP
(HyperText Transfer Protocol) servers to be created before Web browsers emerged
as the "killer app" for the Internet.[27,87,88] Proprietary e-mail systems and
on-line content services did not move to open Internet standards
until a critical
mass of Web-browsable content was available and being actively explored and

Hence, the first step in WorldBoard economic feasibility has to be the
availability of large quantities of geocoded content. Proprietary geocoded
content services will likely emerge (they already exist in numerous GIS
[geographic information system] databases). However, broad adoption of
WorldBoard-like capabilities cannot occur until large quantities of geocoded
content are publicly available. Researchers and others must have a
reason to use
WorldBoard, as well as a way to easily read and write spatially addressable
messages. Spatially addressable messages are sometimes directed at a particular
person in a place, but are often directed at anyone in a place.

There are many potential sources of on-line geocoded content.
Government agencies
are one obvious producer. In fact, many states are developing geospatial
information infrastructure strategies.[89] A government initiative, to make
geospatial data easily accessible to citizens and businesses to stimulate
economic development, could be an important first step to economic feasibility
for WorldBoard services. The federal government could take the lead to improve
general safety, emergency response, and disaster planning. For example, many
costly accidents happen each day. Backhoes and bulldozers accidentally cause
millions of dollars' worth of damage by cutting underground cables
and pipes.[90]
The easy access to small rental backhoes and the increase in costly
accidents may
cause an insurance and legislative backlash to occur at some point.

In the United States, legislative action surrounding geocoded information has
already begun. Federal Communications Commission (FCC) regulation E911 requires
all cellular phone manufacturers to provide a mechanism for locating telephones
on which the emergency number 911 is dialed to within about 100
meters, no later
than October 1, 2001. In some regions over 30 percent of all 911 calls are made
on mobile phones, and this percentage is on the rise. The federal
government paid
for the GPS system, and funding the development of WorldBoard servers populated
with geospatial data possessed by government agencies would be an
important step
toward further economic development.

Several protocols for GPS-based addressing and routing for the
Internet have been
proposed. For example, Julio C. Navas of Rutgers University[91] has
been working
to integrate the concept of physical location into the current design of the
Internet, which relies on logical addressing. He proposes "georouting" and
"geocasting" to send geocoded messages (such as "bridge out ahead") to mobile
computing devices. Geographic routing (georouting) uses polygonal geographic
destination information in the geographic message header for routing. His
approach uses about eight bytes of information to address any .1 square-mile
region in the world. In addition, Navas proposes a GeoARP protocol to populate
areas with objects of interest. Like the ARP (Address Resolution
Protocol), where
individual hosts respond with their IP (Internet Protocol) addresses to an ARP
broadcast, in the GeoARP protocol, hosts respond with their GPS coordinates.

Once government agencies "prime the pump," the travel and tourism businesses
might move geocoded content onto WorldBoard servers. The "killer app" for this
industry might be virtual tourism, helping consumers plan vacations, perhaps
selecting the hotel room or table at a restaurant with the best view. Tourists
might browse information left by others about hotels, restaurants, and local

Other sources of geocoded content include: educational activities (part of the
original WorldBoard vision), utility companies, satellite data, and scientific
fieldwork. Several companies are producing database and authoring tools for
geocoded information.[92-95] In addition, applications with a geospatial
component that are in the works for the Palm VII** are suggestive of sources of
geocoded content: movie times and locations, ATM (automatic teller machine)
locator services, traffic and road conditions, driving directions, weather
conditions, sports and local news, Internet "yellow pages" businesses locators,
and parcel tracking services.[96]

Ultimately, like the Web, the economic feasibility of WorldBoard businesses may
derive from advertising. As visitors are going on virtual tours, they could see
virtual billboards. Later as consumer electronics companies produce viable
WorldBoard mobile clients and glasses, along with information "in its place,"
consumers may see advertisements from the sponsors who put them there. In the
next section, a range of WorldBoard applications is discussed.

Potential applications

WorldBoard-like technologies provide an opportunity to contextualize
some of the
vast quantities of spatial data in the world. From this perspective, WorldBoard
is a method for organizing information that provides a simple place for
individuals and businesses to put information and a simple way to
find and share
information. While WorldBoard was originally motivated by educational
considerations, as outlined in an early section of this paper, many business
opportunities exist for WorldBoard. For example, as previously mentioned with
respect to improving public safety, one can easily imagine the benefits of
utilizing GIS (geographic information system) data about underground
buried pipes
and cables. Visualizations of where cables and pipes are buried could help
construction equipment operators avoid costly accidents. (See Figure 2.)
Unfortunately, almost every day, backhoe operators accidentally damage
underground pipes and cables. In the case of pipes, environmental cleanup costs
alone often run into millions of dollars per incident. The frequency
and cost of
these accidents are tracked at the Web site Insurance
companies, construction equipment manufacturers, and government
organizations are
just some of the many organizations with a vested interest in
promoting improved
safety by making use of GIS information and location-aware devices.

Over the next decade, many devices will quite likely become location-aware. Our
cars, wristwatches, phones, computers, and just about anything else that is
mobile and has a chip in it will be location-aware and
communication-enabled. FCC
regulation E911 will be one of the driving forces affecting
devices. As previously discussed, E911 mandates that all cellular
phones sold in
the United States must be location-aware by October 1, 2001, to provide better
emergency response to 911 calls. All of these mobile, location-aware
devices will
very likely have unique digital identification codes as well. Even ignoring
WorldBoard applications that derive value from an ability to associate
information with a place, the implications of ubiquitous location-aware devices
are quite significant. First, theft of devices will become more difficult, when
devices can "phone home" or simply stop working when their authorized user or
owner is not operating them. Second, inventory control, transportation, and
shopping efficiencies will improve to unprecedented levels. Imagine the cost
savings when a company can at the push of a button get a complete inventory as
well as the location of assets. Third, individuals will waste much less time
looking for destinations, lost things, and each other in crowded places. Paul
Saffo[97] of the Institute for the Future foresees the day when it will be
cheaper to know the location of most packages being shipped than to pay the
postage to send them to their destination. In sum, many forces (in addition to
WorldBoard-like efforts) will be driving the trend toward greater numbers of
location-aware devices.

In this section, the benefits of improved ways to organize and utilize spatial
information are explored, as well as the benefits of devices that provide users
with location-aware and context-aware applications and services. Location-aware
applications benefit from access to the knowledge of where a user is.
Context-aware applications benefit from knowing not only where a user is, but
also information about the activity the user is engaged in and local
environmental conditions. Location and time of day can be very powerful
predictors of likely activities and environmental conditions, as well
as indices
to on-line information that may be of great relevance to a user--for
example, to
access a local weather report.

Recent augmented-reality applications. In the process of performing
some complex
task, a user's performance (speed, accuracy, reliability) may be
enhanced through
the use of timely and appropriate additional information. However, interrupting
the process to refer to a printed manual or even to listen to and act on vague
bits of advice ("OK, line it up with the valve to your right") can be
and confusing. In November 1999, at the First IEEE Workshop on
Augmented Reality,
a number of augmented-reality applications were described in which a user was
provided with additional information during the performance of a task. This was
done in ways designed not to distract or confuse the user, but to enhance
performance on a task. Navab[98] described an industrial
augmented-reality system
to assist service and maintenance personnel working on complex
pipelines in power
or chemical factories--overlaying blueprint information, color-coding pipes and
wires, and labeling specific valves and assemblies. Starner and
colleagues[99] at
the MIT Media Lab described an augmented reality system, called
Stochasticks, to
enhance the game of billiards--overlaying alignment, angle, and banking
information. Molineros[100] described an augmented-reality system for
assembly sequences in robot assembly planning. Curtis[101] described
an augmented
reality system for use in airplane factories for constructing aircraft
wire-bundle assemblies--overlaying the path of current wire through the bundle.
Reiners[102] described an augmented-reality system for assisting the
assembly of
a door lock into a car door--overlaying hidden or obscured areas and sequencing
steps. Berger[103] described a medical application to guide treatment for eye
disease--utilizing overlays from preoperation planning. Satoh[104] described an
augmented-reality air hockey game with a virtual puck.

Billinghurst[105] described an augmented-reality communication space to see and
interact with others. Social augmented-reality systems such as this are still
rare. Nevertheless, group authoring expeditions are beginning to occur. The
Digital Explorers Society (DEX, promotes the notion of
digital expeditions that record data in context. DEX members include
adventurers, and technologists.

Pascoe and his colleagues at the University of Kent developed a
prototype system
that combined a 3Com PalmPilot with a Garmin GPS 45 for use by an ecologist who
spent two months observing giraffes in Kenya.[106] Not only could
ecologists more
easily collect geocoded data, but they could also post messages that
might be of
value to other ecologists doing similar observations at the same location at a
later time. As a result of this experience, a number of integration problems
became apparent due to the variety of hardware and software components that
needed to be put together to build this kind of mobile context-aware
solution. To
address these integration problems Pascoe has proposed a contextual information
service (CIS) architecture on which to build future systems. Pascoe notes that
just as standards were needed in the early days of the Internet,
common protocols
for integrating diverse hardware and software are needed now to create
"plug-and-play" contextual information services that can combine
components from
various vendors and researchers.

In addition, Pascoe[106] and others[107] have begun to define categories of
context-aware applications. For example, Pascoe describes four basic
that can be used in defining context-aware applications.

1. Sensing: Sensor data presented to user (e.g., "you are here" on a map)
2. Adaptation: Sense and adapt application behavior (e.g., clock sets itself to
    local time on entering a new time zone)
3. Resource discovery: Sensing and adapting to use local physical resources
    (e.g., a mobile computer identifies a local printer on which to print)
4. Augmentation: Sensing and adapting to use local physical and
virtual resources
    (e.g., virtual signs appear over buildings as part of a tour)

Within this framework, the augmented-reality applications described earlier can
be seen to use sensing (positioning, cameras) capabilities, to adapt generic
information templates, and to augment the information from the
physical world to
support users performing various tasks. In the next section, an alternative
capability framework is proposed for WorldBoard applications.

WorldBoard application capabilities. The opportunity for WorldBoard
exists when there is a good answer to the question: Where is the best place to
put a particular piece of information? Sometimes the answer to this question is
obvious because the information has spatial attributes, and other times the
answer must be arrived at indirectly through a series of inferences about its
spatial utility:

1. Spatial information. A question that can be asked about any information
resource is: Does this information resource contain spatial data? Some
information has spatial attributes or dimensions associated with it, which give
it either a natural place to be stored or a natural way to be
visualized (or more
generally perceived) in a spatial context. For example, all of the
following have
spatial attributes--geographic information system (GIS) data,
telephone books and
"yellow pages," address books, maps, architectural plans, and CAD
design) diagrams. By some estimates, over 50 percent of business data have
spatial attributes. Your location and the location of each of your possessions
are important spatial attributes. Any place you are trying to get to,
or plan to
go to, as well as all the places that you have been, have spatial attributes.
When you use a camera to take a picture, your location and orientation are
spatial attributes that can be used to add geocoding metadata to the picture.
Thus all photographs have associated spatial data, and in general all human
artifacts have a creation location, current location, location history, etc.

2. Spatial utility. A second question that can be asked about any information
resource is: Where should this piece of information be put to
maximize its value
to a person or organization? Some information is more useful or makes
more sense
at one place or set of places than another. For example,
advertisements are most
effective when placed in heavy traffic areas where they are likely to get more
attention. Demographic data can have spatial attributes (zip codes),
and specific
advertisements have utility attributes that correspond to particular
values. Sports statistics about a baseball player may or may not have spatial
attributes, but when a player is at a particular ball park, the player's
statistics have higher utility to fans watching the game than the
statistics for
a player who is not at the park.

WorldBoard applications arise when useful information can be put
exactly where it
is needed most. Often businesses and individuals know exactly where they want
information to be or how they would like to perceive the information, but for
reasons of cost, insufficient physical space, insufficient structural integrity
of materials, esthetics, or convenience, information ends up in a suboptimal
place. WorldBoard will have economic and quality-of-life benefits in direct
proportion to how well it supports (1) improved placement of information
resources (associating information with places), and (2) improved perception of

WorldBoard benefits arise from new capabilities that developers can incorporate
into applications. These new capabilities are:

1. The ability to easily associate information resources with a place

o Messages and signs at a location--virtual signs that are less expensive or
contain more details than physical signs, advertisements, warnings,
labels, names
of things in multiple languages, names of plants, names of buildings,
lists with questions and answers, reminders, personal postcards,
navigation aids,
real-estate buyer and seller information, archaeological and
ecological records,
safety and emergency information signs and warnings required by fire,
police, and
emergency response organizations

o Virtual objects at a location--virtual works of art, entertaining objects,
educational objects, virtual instruction manuals, and educational
simulations of
objects at a location

o Programs and interactive characters at a location--data collection programs
that are triggered when location-aware devices arrive at a location,
virtual tour
guides in museums, parks, etc., sales persons, theme-park characters, and
historical characters

2. The ability to perceive information about or at places in new ways

o Ability to see hidden parts of things--virtual X-ray vision through walls,
clouds, and underground; cutaways into man-made and natural things; ability to
see through buildings, obstructions, and the surface of the earth;
ability to see
buried infrastructure such as pipes and cables and building infrastructure such
as wiring, plumbing, and physical structure; ability to see construction and
excavation blueprints

o Ability to see invisible things, both natural and
cultural--normally invisible
sensor data, radiation levels, lines of force, microscopic structure, infrared,
night vision, other parts of the electromagnetic spectrum; property
lines, rights
of way; satellite trajectories; dynamic processes, special effects; and
constellations and names of planets

o Ability to change the appearance of things--real-estate landscaping, full
potential of properties, and color of walls

o Ability to add highlights and overlays--color- coded parts of a
complex scene,
such as factory pipes in a heating plant; highlighted architectural
characteristics, crumbling infrastructure, other perspectives that highlight or
downplay various aspects of a visual scene; storage location of hazardous,
flammable, or toxic materials in warehouses and in transportation yards as well
as on highways

o Ability to see what was or what could be--historical records, personal
records; architectural plans, city plans, Olympics host competition model sites

3. The ability to receive location-based consumer information services--"Yellow
pages" and spatial queries on GIS databases; traffic, weather
reports; queries on
related map-based information; and tracking information for personal

Each of these abilities will allow the creation of many vertical applications,
but the question of what are the broad-based horizontal applications for
WorldBoard remains unanswered.

Communication medium and perception tool. WorldBoard can be viewed as
both a new
type of communication medium and a new type of perception tool. Communication
media, such as television, the Web, telephone, radio, and publications, allow
individuals and organizations to send and receive messages that entertain,
educate, inform, and market as well as amplify our social awareness. Perception
tools, such as vision-correction glasses, microscopes, telescopes, and night
vision goggles, amplify our senses. In this section, both perspectives are
examined to generate a few basic questions and then suggest some possible

Viewed as a public communication medium we can ask: How might businesses use
information in places to support commerce, advertising, and information
presentation? Just as businesses now put information on the Web or on
they may put information in places using WorldBoard-like systems--but
only if (1)
enough customers are "tuned in" to WorldBoard channels, and (2) it is easy to
create content for WorldBoard in a cost-effective manner. Alternatively, viewed
as a personal communication medium we can ask: How might individuals creatively
use the infrastructure for mundane personal tasks? For example, how
might family
members use WorldBoard to place virtual greeting cards or reminders in places
where other members of the family are most likely to see them?

One possible answer to these questions is that WorldBoard may evolve by first
becoming a Web portal, where WorldBoard authoring tools are simply
standard tools
for creating Web pages, and WorldBoard perception tools are simply
Web browsers.
As mentioned earlier, in the proposed first step of the WorldBoard development
plan, using the Web to bootstrap WorldBoard is a realistic and likely scenario.
For example, MapQuest[95] and Microsoft's TerraServer[46] allow
anyone with a Web
browser to "zoom in" on any part of the planet, either with a map (MapQuest) or
with satellite and aerial photographs (TerraServer). Yahoo!** and other portals
provide map and direction services as well.

A possible next step is to allow users to post information to these servers in
password-protected channel areas. Archaeologists might post precise photographs
and locations of artifacts to allow colleagues in remote locations to inspect
their finds, and families might purchase cameras that automatically geocode and
upload photographs to be browsed by far-away family members.
Colleagues or family
members could leave a spatial bookmark on their WebTV** browser, and quickly
check on any updates in posted information--perhaps returning comments of their
own on the new additions.

Viewed as a perception tool, we can ask how workers might be able to do their
jobs more efficiently, effectively, enjoyably, or safely, or what
might happen if
workers could visualize the inert knowledge, locked in remote databases, in
appropriate contexts. But how will the workers see the information, since it is
unlikely that any time soon they will be wearing heads-up displays?
Again, viewed
as a perception tool, we can ask how individuals in museums or national parks
might "virtually zoom in" on a tree or a rock and get annotated
information about
the microscopic structure of an organism. When learning about GPS,
for instance,
a learner might look up and get a virtual planetarium with the actual positions
of GPS satellites shown as they trace their paths in the sky. But how will
individuals get access to WorldBoard-capable display systems? Will ordinary
people start making extraordinary observations when equipped with
these devices?
How might enhanced perception lead to new discoveries? How could enhanced
perception tools amplify the collective efforts of many people?

One possible answer to these questions is that WorldBoard may evolve from
location-based information services on location-aware cellular phones and
hand-held computers. Hotel and restaurant chains, gasoline stations, taxi
companies, and other service providers could benefit by providing information
about the location of nearby services. As these devices connect to
the Internet,
consumers may be able to access WorldBoard-like portals described
earlier to view
and post geocoded information. In particular, if these devices contain cameras
(either for teleconferencing, taking pictures, scanning business cards, or
sending faxes), then the door is opened to providing superimposed
information on
the displayed camera image. Probably, the first application of information
overlay will be to provide travel information about the names of streets,
buildings, directions, and other information easily packaged in an
overlayed sign
or graphic. In addition, if large numbers of users are routinely
carrying around
a device that allows them to take a picture, annotate it, and post it to a
WorldBoard channel, the threshold will be lowered for rapidly
collecting massive
amounts of time-and-place-stamped information from many perspectives. Amateur
botanists or entomologists can easily upload information with accurate
time-and-place stamps that can then be inspected automatically or
manually to see
if new species have been discovered.

The information explosion is well documented,[108] as are the frustrations of
users who often complain that information is too hard to find and to use
conveniently.[109] WorldBoard provides one way to improve the
convenience of both
finding and using certain kinds of information.

If WorldBoard could be realized, it might make finding (accessing) information
more convenient by improving the precision and context sensitivity of
search and
retrieval technology through the use of spatial cues. Information in places is
context-sensitive information. Just as we keep wrenches in the garage and forks
in the kitchen, WorldBoard promotes the view of a place for information and
information in its place. The business goal of making high-quality information
materials more available might be achieved if low-cost information appliances
could allow customers to access information in a context where it is most
valuable. WorldBoard capabilities would encourage creators of information to
think about where the information belongs and how best to put it there.
Information architects might then be asking: "Where, when, and how
will a person
be most able to make use of the information I have to offer?" We need
communication media and perception tools that help optimize finding and using
information if we are to make the most effective use of the vast wealth of
resources we are creating, both as individuals and as a whole society.

If WorldBoard could be realized, it might improve the convenience of using
certain kinds of information as well. When information is more
optimally conveyed
to the human perception system, it can be more efficiently utilized with less
mental and physical effort. For example, imagine the difference between looking
up at the sky and seeing the constellations and names of stars in place, vs
looking at a book containing the information and having to move one's head back
and forth to verify that one is actually mapping the information onto the
appropriate part of the sky. Typically, a person is juggling a flashlight, the
wind is blowing the paper, and because of the time it takes for one's
eyes to go
between daylight vision and night vision, the experience leaves much to be
desired. Planetariums have been constructed to give people the
illusion of seeing
information about the sky in its proper place. WorldBoard
capabilities allow for
the construction of personal planetariums and shared personal
planetariums--combining our perception of the real sky with the information our
culture has created about it.

In sum, the need for applications can be supported by either the
communication-medium or perception-tool aspects of the technology. Information
associated with places can be easier to find and to process than out-of-context
information. Of course, not all information can be contextualized in this way.

Social implications

Will this idea catch on? Or will putting information in places merely be an
oddity, a technological "side show," that never quite worked right or
had enough
utility to become a truly viable global information service? Perhaps negative
social implications will be discovered that limit adoption. In this
section, the
technical feasibility of WorldBoard will be assumed, but social issues will be
examined. While not exhaustive, all of these issues have been raised
by others as
objections to WorldBoard.

Personal privacy. While there are arguments for tracking prisoners and certain
medical patients, tracking an individual's location has the potential to be a
significant invasion of privacy. The potential for misuse of tracking
is significant.[110,111] If an organization is tracking its equipment for
inventory control purposes, and an employee is in possession of a communicating
location-aware device, then the employer can know the detailed
whereabouts of the

Nevertheless, organizations already possess personal and highly sensitive
information about employees, and new policy and procedures will need to be
developed. Furthermore, tracking of children will also be possible. This may be
especially useful at theme parks or in other crowded public places. The
trade-offs will include privacy concerns, enhanced security and safety, and
perhaps enhanced services that can only be provided if some personal
is shared. Sharing of personal information is increasingly the basis
of Web-based
business models.[112]

Technological "haves" and "have-nots." Access to technology is an issue of
increasing concern to a number of organizations.[113] What if
WorldBoard becomes
a reality, but because of its cost, sections of the population become
increasingly marginalized or relegated to less desirable careers and living
conditions? This might become a genuine concern, because the
incremental cost of
WorldBoard-enabled devices over simple Web browsers or cellular phones could be
significant due to higher communication bandwidth, processor power, storage
capability, and battery power requirements. However, the business model of
sharing personal information to obtain free or low-cost devices seems to be on
the rise. Alternatively, society has many mechanisms for dealing with
other than business model innovations. If Web access or any other type of
technology access became the major rallying cry of a large portion of the
population, these other methods of addressing the inequity (including taxes and
entitlement legislation) would most likely be considered. A more serious cost
concern may be for schools. If WorldBoard does prove to be of significant value
in education, will schools have the funds to provide WorldBoard-capable devices
to their students? Again, as the business experiments unfold (like the ZapMe!**
netspace,[112] which gives schools free or low-cost computers in exchange for
allowing students to see targeted advertisements a certain percentage of the
day), it will be easier to determine whether there is a socially
responsible way
to use such methods to address the issue.

Propaganda, altering perceptions of reality, and graffiti. The ability to
transform perception has important ramifications. For example, a
politician might
urge citizens to become aware of the crumbling infrastructure of a
city by tuning
in a WorldBoard information channel. The channels could be loaded with the
politician's particular world view, amplifying what the politician sees that
needs changing. A shared world view can help mobilize and coordinate
the actions
of many citizens--the power of the press to shape views and opinions is nothing
new. Nevertheless, the notion of a socially constructed reality could take on a
new, more literal meaning. But will coherence emerge, or simply a cacophony of
views? The benefits of contextualized information could be lessened
if there are
too many WorldBoard channels to search and choose from, and if the material on
any channel is authored by too many individuals with too many styles and
viewpoints. Will there be a channel for Democrats and a channel for
each highlighting issues with a political agenda attached?

WorldBoard also supports virtual graffiti. If WorldBoard becomes real, it is
likely that one WorldBoard channel will be totally open to whomever
wants to post
information into a space. Recall that a WorldBoard channel is a mechanism for
allowing security, privacy, and protection of what is posted to
WorldBoard. There
will be many channels, and companies will have their own channels with their
version of reality available. Why then would anyone ever look at the "anything
goes" channel? Curiosity is probably the main motivation for readers, and
publishing to a potentially large audience for writers. Some viewers might be
curious about what others have posted to the coordinates of the walls
or ceiling
in the Oval Office or other rooms in the White House. What channels will exist,
who can post to them, and what the rights are of perceivers and
posters are just
some of the open questions. The Internet will undoubtedly be the basis for
WorldBoard, not only as technological underpinning, but in legal precedent on
thorny issues as well.

Media addiction and disconnecting from reality. How do citizens of the
information age in the United States spend their time? We are tremendous
producers and consumers of information. A report published by the United States
Department of Commerce[114] estimates the media usage of an average citizen in
1995 to be a total of 3401 hours, broken down by media category and
hours-per-year usage (see Table 1).

Table 1 Estimate of media usage by average United States citizen

Media Categories Hours Used
                              per Year

Television 1575
Radio 1091
Recorded music 289
Newspapers 165
Books 99
Magazines 84
Home video 53
Home video games 24
Movies in theaters 12
On-line/Internet 7
Educational software 2

Background music or televisions in waiting rooms, restaurants, and other places
provide an information ambiance to surround people. In addition to media usage
that can be quite passive, the average U.S. citizen makes about six telephone
calls a day, lasting on average three minutes each. The average person spends
more than ten hours a day using media or making telephone calls, more time than

When a new media technology appears, we hear stories of individuals becoming
addicted to using that technology. In a fully functional WorldBoard,
changing the
colors of the walls, the appearance of furniture, or even personal appearance
when one looks in the mirror is possible. Some viewers may prefer the
"rose-colored glasses" of WorldBoard to the harsh realities of the
real world. As
we invent computers that are aware of our emotional state or real physiological
needs, rose-colored glasses may alter our perceptions of reality to cheer us up
or make things seem brighter or illuminated by brighter sunlight.

More realistically, what happens if individuals start depending on
WorldBoard for
their safety, income, or other essential parts of life, and the
technology fails,
locally or on a global scale? Again, this problem is not unique to WorldBoard,
but is inherent in a society dependent on a technological
infrastructure for its
smooth operation. Nevertheless, if the complete WorldBoard vision is realized,
greater and greater levels of technological dependence will be
encouraged as more
and more aspects of life benefit from WorldBoard capabilities.

Terrorism and malicious use of information. Technologies can be misused or used
for undesirable ends. For example, even something as seemingly harmless as the
wristwatch was viewed warily when it was invented over three hundred years
ago.[115] The newspapers at the time published a story of how an enemy equipped
with accurate chronometers could launch a devastating synchronized
attack across
all of England. More recently, newspapers warned that terrorists could use
commercially available GPS systems to obtain information that would
allow them to
direct missile attacks. Also, in the same way that backhoe operators could use
visualizations of buried cables and pipes to avoid accidents, a malicious
operator could use the information to inflict maximum damage in a remote area.

Reflections: Trends and alternatives

The realization of a global infrastructure for associating information with
places and supporting enhanced perception services will very likely unfold in
surprising ways. More often than not, the way we imagine emerging technologies,
and the way they actually turn out is quite different. Thus in concluding this
paper it is reasonable to ask: What are the confirming trends
indicating that we
might be on the right path in our thinking? What are the alternatives? Are we
even thinking about the capability of putting information in its place in a
reasonable way?

Confirming trends. To date, the potential applications of WorldBoard seem to be
largely "vertical" markets. A broad-based horizontal "killer app" for
geospatial browsers, and augmented reality has not been identified.[27,87]
Nevertheless, WorldBoard can be seen as part of three trends:

1. Atoms to bits: Why deal with a physical object, when the
information object is
easier to make and manipulate (e.g., physical to CAD models,
typewritten page to
word processor document)?

2. Stationary to mobile device: Why go to the communication device or
appliance, when the device can go with you (cellular phone, wearable radio,
television, or watch)?

3. Senses to instruments: Why settle for normal senses, when instruments can
bring you more information (e.g., corrective lenses, hearing aids, telescope,
microscope, radar, sonar, night-vision binoculars, sensors)?

As we learn to create and interact with information objects in real space, the
relationship between people and information will be changed. One
could argue that
our success as individuals and as a species depends on our ability to record,
manipulate, and access information. All too often we find ourselves
struggling to
remember, scrambling to find the right person to call, flying off or
dashing off
to a meeting, fumbling with books or devices to look things up, or hopelessly
awash in too much information. Imagine instead a world where
information is right
where we need it most, readily at hand.

Throughout human history, the relationship between people and information has
been of fundamental importance. The cognitive age of humans started
when we used
representations of the real (sound, gesture, symbols) to refer to the
Each new representation has advantages and disadvantages. For example, Socrates
argued against books, since they could merely remind us of the
thoughts of others
and did not support true inquiry and questioning unless the author accompanied
the book. Our relationship with information is determined in part by
our methods
of producing, communicating, and consuming information, as well as our methods
for establishing the ownership, privacy, and quality of information. Consider a
sampling of milestones in this story, summarized in Table 2. (A generation is
about 15 to 20 years.)

Table 2 Milestones in representation and use of information

  Generations Milestones

   100 000 Speech
    17 000 Planning ahead
       500 Writing
       400 Libraries
        40 Universities
        24 Printing
        16 Accurate clocks
         5 Telephone
         4 Radio
         3 Television
         2 Computers
         1 Internet
         0 GPS

No one would deny that each of the milestones in Table 2 has had a significant
and profound impact on our human relationship to information or our ability to
use information more effectively. If this accelerating trend
continues, the next
decade will result in multiple new milestones of historic significance.
WorldBoard is but one of many technology forecasts that describe a new
relationship between people and information. Gelernter's Mirror Worlds and
TimeStreams,[50] as well as Weiser's ubiquitous computing[117] are
other examples
of predictions of fundamental changes in our relationships to information and
technology. While technical barriers still exist, these might well be overcome
quite soon, and then the social and economic barriers would be all that remain.

Unexpected alternatives. Before describing some of the ways in which WorldBoard
might turn out differently than has been described here, it will be useful to
look at an earlier technology forecast. In particular, we examine a forecast
that, like WorldBoard, was motivated by a desire to create a new relationship
between people and information.

In July 1945, The Atlantic Monthly published an article entitled "As We May
Think," by Dr. Vannevar Bush, then Director of the U.S. Office of Scientific
Research and Development. In the article118 Bush called for a new relationship
between people and the sum of their knowledge. To motivate the need for the new
relationship, Bush cited problems caused by an overabundance of information
becoming increasingly too large to conveniently search, as well as information
not getting to those best able to utilize it (note that finding and utilizing
information are core aspects of WorldBoard):

The summation of human experience is being expanded at a prodigious
rate, and the
means we use for threading through the consequent maze to the momentarily
important item is the same as was used in the days of square-rigged ships
Mendel's concept of the laws of genetics was lost to the world for a generation
because his publication did not reach the few who were capable of grasping and
extending it. This sort of catastrophe is undoubtedly being repeated
all about us
as truly significant attainments become lost in the mass of the
Publication has been extended far beyond our present ability to make use of the

Bush proposed technologies ("instrumentalities") that we now recognize as
cameras, microfilm, speech recognition, artificial intelligence, and
the Internet
as the basis for redefining the relationship between people and
information. The
new relationship would use technologies to help people produce, store,
manipulate, and consult the "record of the race." However, more than 50 years
later, while devices like those that Bush predicted do in fact exist, their
physical form and internal operations are substantially different. For example,
consider Bush's description of the "memex," a device for storing all books,
records, and communications, to be consulted with exceeding speed and

It consists of a desk, and while it can presumably be operated from a distance,
it is primarily the piece of furniture at which he works. On the top
are slanting
translucent screens on which material can be projected for convenient reading.
There is a keyboard and sets of buttons and levers. Otherwise it looks like an
ordinary desk if the user inserted 5,000 pages of material a day it would take
him hundreds of years to fill up the repository Most of the memex
contents are
purchased on microfilm ready for insertion On the top of the memex is a
transparent platen. On this are placed longhand notes, photographs the
depression of a lever causes it to be photographed onto the next blank page On
deflecting one of the levers to the right he runs through the book before him,
each page in turn being projected at a speed which just allows a recognizing
glance of each one He can add marginal notes and comments, taking advantage of
one possible type of dry photography, and it could even be arranged so that he
can do this by a stylus scheme, such as is now employed in the
teleautograph seen
in railroad waiting rooms

The point is simply that in trying to make technology forecasts, existing
technologies (microfilm for storage) and ways of thinking (mechanical levers)
serve as the point of departure for our thoughts as we project
forward. In order
to seem plausible, the forecasts are based on directly relevant existing or
emerging technologies. So one of the ways the proposed WorldBoard, based on
global positioning, global wireless communications, and mobile display
technologies, may change is that even more radical capabilities may emerge that
provide more efficient means for implementing information in places.
For example,
breakthroughs in any of the following areas (or more likely areas not
here at all) could create alternative realizations of WorldBoard on very
different technological foundations:

1. Human perception and memory model extrapolated--vision recognition
capabilities that allow a camera to know where it is (exact location)
and what it
is looking at. (This is the human perception and memory model extrapolated.)

2. Molecular marker model extrapolated--ubiquitous computing aerosols or paints
that can be sprayed on any material to provide unique and customizable digital
identifiers that are easily sensed[120,121]

3. Projection displays extrapolated to eliminate the projector--a variation of
the ubiquitous computing aerosol that can be sprayed on any material as a clear
coating that can change its optical qualities, turning any object
coated with the
material into an optical chameleon

4. Human-computer interface model extrapolated--bionic sensor and effector
advances that better leverage or directly amplify existing human-computer
interface capabilities

The bottom line is that while there is clear utility to being able to better
associate information with places, it is less clear how that capability will
ultimately be realized. As the "memex" example helps to illustrate, WorldBoard
will probably be realized using technologies far more intriguing than
the simple
positioning, communication, and display technologies described in
this paper and
that we are familiar with today. Nevertheless, by one technological route or
another, we are on the verge of being able to put information in its place on a
planetary scale.

To succeed, WorldBoard must not only integrate a number of rapidly evolving
technologies (positioning, communication, displays, sensors), but
accomplish the
integration in an economically viable manner. Senge[122] made this integration
point with respect to successful commercial aviation:

The Wright Brothers proved that powered flight was possible, but the McDonnell
Douglas DC-3, introduced in 1935 ushered in the era of commercial air
travel. The
DC-3 was the first plane that supported itself economically as well as
aerodynamically. The DC-3, for the first time, brought together five critical
component technologies that formed a successful ensemble. They were
the variable
pitch propeller, retractable landing gear, a type of lightweight molded body
construction called "monocque," radial air-cooled engine, and wing flaps. One
year earlier, the Boeing 247 was introduced with all the features
except the wing
flaps, [and was less successful because of unstable takeoffs and landings].

Left unsaid in Senge's anecdote of the success of the DC-3 is the
important point
that people were willing to get on planes and fly through the air to their
destinations--no small step for humankind. Nevertheless, the dream of
flying is a
common experience, unlike the dream of seeing information in its place.

Concluding remarks

A broad overview of the WorldBoard concept has been presented.
Specifically, the
benefits and technical feasibility of WorldBoard have been argued here. The key
benefit of WorldBoard is contextualized information that can make information
easier to find and utilize. The technical feasibility of WorldBoard can be
decomposed into two parts: (1) a Web-based infrastructure to support
information with places, and (2) devices that support the perception of
information in places. The former is technically feasible, but usability issues
(how to effectively navigate to and post messages to WorldBoard channels and
places in a Web browser tool) and utility issues (who derives what benefit from
posting and viewing messages on WorldBoard channels) remain unanswered. The
technical feasibility of devices that support the perception of information in
places is in part addressed through existing augmented-reality system
but mobility issues (how to make the systems small and robust) and quality of
experience issues (availability of useful content, broad and uniform
and communication infrastructure, display and seamless integration of
virtual and
real images) remain unanswered.

If the complete WorldBoard vision is realized, then elements of human culture
will become perceptually apparent, enhancing our ability to learn and make
effective use of abundant information resources in context. Furthermore, this
innovation could change our control over the environment, our notion of place,
and our human relationship to information. Toward this end, the Web site has been established by researchers interested in
working together on open standards to create a WorldBoard.


This work was supported by the National Science Foundation under grant
CDA-948609. The name "WorldBoard" is used with permission of
WorldBoard, Inc. Ian
May created the graphics for this paper. The works of Gregory Abowd, Steven
Feiner, Blair Macintyre, Thad Starner, and Warren Robinett have been especially
influential in the development of the ideas presented here. I am grateful to
Marty Siegel and Sonny Kirkley of the Indiana University and Wisdom Tools for
creating the WorldBoard Web site at, and for
continuing to drive WorldBoard development. Arthur Woo, Ian Bruce, and Ruben
Kleiman have contributed to the ideas presented here. I am grateful for many
stimulating conversations about the future of technology (over the years) with
Doug Engelbart, Alan Kay, Mark L. Miller, Don Norman, Roger Schank, Ted Selker,
Elliot Soloway, and Gary Starkweather. I thank my colleagues at IBM Almaden as
well. Finally, I wish to thank the anonymous referees for their many
and ideas.


NAVSTAR (Navigation Satellite Timing and Ranging) GPS became operational in
December, 1993, for both military and civilian use. Twenty-four GPS satellites,
deployed by the U.S. Department of Defense at a cost of $8-10 billion, were
operating simultaneously by 1994. GPS satellites use frequencies L1 =
1575.42 MHz
(megahertz) and L2 = 1227.6 MHz (two frequencies are important for mitigating
certain positioning error terms).

Two types of codes modulate these frequencies: the coarse acquisition
(C/A) code
and the precision (P) code. C/A code provides an SPS (standard positioning
service), which is accurate to 100 meters 95 percent of the time. C/A
signals are
degraded by falsification of the satellite clock and of the ephemeris
part of the
navigation message. P code provides a PPS (precise positioning
service). In 1994,
antispoofing (encryption) was implemented to ensure that the P code
is available
only to military users--although in practice this can be circumvented
in several

The encrypted P code is termed the Y code. Ground-based GPS receivers typically
measure "pseudo range" and carrier phase from the received satellite signals.
Pseudo range is the distance between the satellite and the receiver, plus small
corrective terms due to clock errors, the ionosphere, the troposphere, and
multipath transmission. Given the geometric position of the
satellites (satellite
ephemeris), four pseudo ranges can be used to compute the position of the
receiver as well as the receiver's clock error. The carrier phase is the
difference between the received phase and the phase of the receiver
oscillator at
the epoch of measurement. Epochs are equally spaced receiver
measurement periods.
Some receivers also count the number of complete cycles received between
measurements, which can be used in very precise kinematic measurements.

The achievable GPS accuracy depends on many factors. Relative positioning of
multiple GPS receivers can be far more accurate than geocentric
positioning of a
single receiver. In relative, or differential positioning, the
relative locations
between receivers is determined, and many errors either cancel out or are
significantly mitigated. Time delay due to the ionosphere is inversely
proportional to the square of the signal frequency, so L1 and L2
together can be
used to eliminate most errors of this type. Other errors can be reduced by
observing signals over longer periods of time, or by transmitting amplified
signal patterns to the receiver from local base stations. With additional
ground-based infrastructure, 2 to 3 millimeter linear-distance
measurements have
been attained using carrier phase measurements as small as .001 cycles. For
example, in 1984 a high-precision GPS survey was done to extend the Stanford
Linear Accelerator, and alignment lasers accurate to .1 millimeter were used to
confirm the high-precision GPS survey results.[123] Around 1985, kinematic GPS
using a stationary base station antenna was developed by
Remondi.[124] Kinematic
GPS has been used for decimeter-level positioning on airplanes as reported by
Mader.[125] As mentioned earlier, very accurate GPS is possible when multiple
ground base stations comprising a GPS network are deployed. Orange County,
California, is one region that has over 2000 stations to support a geographic
information system in that region.[126]

**Trademark or registered trademark of LEGO Systems, Incorporated, i-O Display
Systems, Lucent Technologies, Apple Computer, Inc., Minnesota Mining and
Manufacturing Company, Sony Electronics, Inc., Nortel Networks Corporation,
Ascension Technology Corporation, Pyramid Systems, Inc., Microsoft Corporation,
Magellan Corporation, Garmin International, 3Com Corporation, Iridium LLC,
Microvision, Inc.,, Inc., Yahoo! Inc., or ZapMe! Corporation.

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Accepted for publication May 20, 1999.

Author bio

James C. Spohrer

IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose,
California 95120 (electronic mail: Dr. Spohrer
is a research
scientist at the IBM Almaden Research Center, where he manages the User
Experience/Human Computer Interaction Research Group. He received a B.S. degree
in physics from the Massachusetts Institute of Technology in 1978, and a Ph.D.
degree in computer science from Yale University in 1987. From 1978 to 1982, he
developed speech recognition technology at Verbex, an Exxon
Enterprises company.
 From 1989 to 1998, he led learning technology and authoring tools projects at
Apple's Advanced Technology Group (ATG), and received Apple's Distinguished
Scientist award. Dr. Spohrer has published broadly in the areas of empirical
studies of programmers, artificial intelligence, authoring tools, on-line
learning communities, intelligent tutoring systems and student modeling, speech
recognition, and new paradigms in using computers. He has also helped to found
two nonprofit Web sites: The Educational Object Economy (http://
and WorldBoard: A Planetary Infrastructure for Associating Information with
Places (http://www.worldboard. org/).

Reprint Order No. G321-5708.

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