Special Feature

Information Navigation Techniques Basedon the Bird’s-eye View Approach
Hidenori Okuda†, Harumi Kawashima, Yoshihide Sato,Shinji Miyahara, and Toru Sadakata
Abstract
In next-generation portal sites, one approach to aiding Internet users who do not have clear search
objectives is to present a bird’s-eye view data map that arouses the user’s interest in a topic. This article
describes a technique for extracting topic words from blogs (Weblogs) or Web news sites and interface
techniques for displaying a large number of keywords and contents on a limited-size screen.

1. Web navigation methods

mation. In such cases, the bird’s-eye view approach iseffective because it allows users to see displays ofoverall data objects on the Internet, in the form of
bird’s-eye view maps and from them find informationthat attracts their interest to guide them in theirsearch. In this way, the bird’s-eye view approach
serves as an additional tool for navigating Web information, supplementing established search services.
This has made research and development on thebird’s-eye view approach a subject of major importance.

According to the Institute for Information andCommunications Policy of the Ministry of Internal
Affairs and Communications [1], in February 2004
there were 85.9 million Web pages in the jp domainalone on the Internet. Two methods of navigating thisenormous body of information are the search-based
approach and the bird’s-eye view approach (Fig. 1).
The search-based approach is the most efficient forusers who have a clear search objective: they cansearch for the information they
desire by using directory services
Search approach: Search for desired data.
and search services. They can also
get easy access to updates in Website
Data on the Internet• Type in search window to get required
contents by using the push-type serdata
vice RSS (rich site summary, RDF• Efficient, but not all data can be viewed(resource description framework)site summary, or really simple syndication). Users who do not have aclear search objective, however, cannot use search services effectively ifthey cannot think of keywords toenter to aid in their search. And they
Bird’s-eye view approach: All images can be acquired.
cannot use RSS because they cannot
specify the Websites from which• Voluminous data can be viewed at outset.
they wish to receive updated infor- User sees what can be done.
• Seeing everything generates interest.

† NTT Cyber Solutions Laboratories
Yokosuka-shi, 239-0847 Japan
E-mail: okuda.hidenori@lab.ntt.co.jp

Vol. 4 No. 8 Aug. 2006

Fig. 1. Methods of navigating information on the Internet.

29

Special Feature

2. Latest topic word extraction technique
Various methods are available for showing bird’seye views of information on the Internet, but in thispaper we focus on the “latest topic word extraction”
technique [2], which enables users to see the degree
to which certain information stands out from the rest.
This technique uses blogs (Weblogs) and Web newssites to show outstanding information and extracts
keywords that directly express contents relevant to
fresh topics. The user can ascertain which topics are
particularly prominent on the Internet at a given time
merely by observing these keywords.
Since Web news sites carry articles on news stories
that are of interest to large segments of the public,
users can judge which stories are most prominent atthat time by observing those for which many articles
have been compiled from multiple news sites at thesame time. In the latest topic word extraction technique, articles are first broadly sorted by genre, e.g.,business, science, or sport. They are then grouped
into specific topics by clustering them on the basis ofwords and expressions appearing in them. Representative words and expressions in each cluster are thenextracted as keywords for a given topic, i.e., topic
words. The flow of the extraction of the latest topic
words from Web news sites is shown in Fig. 2.
With blogs, on the other hand, people write in diary
form about aspects of topics that stir their emotions,and Web users can use blogs to ascertain which topics are stirring passions around the globe by noting
those that are treated in many different blogs. Blogs

Genre 1have certain unique characteristics: one is that bloggers often include multiple topics in one posting;another is that different bloggers may use different
words and expressions to refer to the same thing intalking about the same topic. In dealing with blogs,
therefore, clustering based on the mere appearance ofwords and expressions cannot be applied to the latest
topic word extraction technique in its current form.
Instead, topic words are extracted by putting weight
on words and expressions that have begun to appear
very frequently in recent blogs.
The system layout of the latest topic word extraction technique is shown in Fig. 3. The system’s article crawler/classifier collects news articles and blog
postings from the Internet and sorts them by genre.
The topic word extractor extracts topic words in themanner described above. The topic word integrator
integrates topic words of two systems and hands themover to the client as data output.
3. Keyword display interface
Here, we introduce the display interface HotWindow+ as an interface technology for efficiently displaying on a limited-size screen a large number of
keywords extracted from information on the Internet.
The HotWindow+ system displays keywords extracted with the latest topic word extraction technique,i.e., topic words on the screen of a client (personalcomputer).
An example of a screen of the HotWindow+ display
interface is shown in Fig. 4. The topic genres appear

Genre 1Cluster 3

News articles

Cluster 1

Genre 2Cluster 2

Latest topic words in
Cluster 1 of Genre 1
Topicword Score
W11 15.8
W12 13.4W13
8.6······Latest topic words in
Cluster 2 of Genre 1

Genre 3Sorted by genre

Arranged by topic

Important words/
expressions inclusters areextracted.

Topicword Score
W21
9.8
W22
9.1
W23
5.4·········Fig. 2. Flow of the extraction of the latest topic words from Web news sites.

30

NTT Technical Review

Special Feature

InternetServerNews sites

Blog sites

Articlecrawler/
classifier

Topicword
integrator

Topicwordextractor

To clientFig. 3. System layout of the “latest topic word extraction” technique.

MOX project
Trustee in a bankruptcy
SocietyPolitics
Economics

Tokyo Stock Exchange
Slight fever

WeightFitness

Fashion and beauty

Medical treatment

Pore
HealthBrand

PENTAX
PC·IT
Entertainment

Fig. 4. Example screen of the HotWindow+ display interface.

in circular regions and topic words for each genre aredisplayed. When the user clicks the genre title in thecenter of a region, the region is magnified and a larger list of topic words appears. When this is done, theother circular regions around the clicked one do notdisappear but remain displayed in small form, so theentire image of the information can still be seen.
Moreover, since it is inconvenient for users who do
not have a clear search objective to have to actively
manipulate the data they are perusing, the system
automatically marks genres that have been magnified. Marking the magnified genres in this way effectively spotlights them, and switching the spotlightVol. 4 No. 8 Aug. 2006

from one genre to another makes it possible to call theuser’s attention to keywords for a wide variety ofgenres.
4. Interface for displaying content items
numbering in the hundreds of thousands
Here, we introduce “High Choukan” [3] as an interface for displaying contents on the order of hundredsof thousands of items, where choukan means bird’seye view in Japanese. This interface effectively steers
users who do not have a clear search objective
towards contents that will likely be of interest to31

Special Featurethem. It does so by giving them an impression of thevoluminous contents, showing what types of contents
are available and stimulating their interest in the contents.
To show users what sort of contents are available,
High Choukan classifies contents by color according
to information type and locates them under background images relevant to the content type. This
enables users to get a bird’s-eye view of the overall
concept of the contents.
Figure 5 shows an example screen, constructedusing High Choukan, which offers a bird’s-eye viewof information about shops, stores, and other such
establishments. The contents in the example comprise some 160,000 data items on dining establishments such as restaurants and hotel restaurants in the23 wards of Tokyo. A map of the area serves as thebackground image. Dining establishments aregrouped by type into colored circles and located overbackground images showing the establishment’s
address and location. Zooming and panning functions
are available for easier navigation. If users wish toacquire details about particular areas they are interested in, they can do so by zooming in on the area inquestion. If they also wish to obtain information
about adjoining areas, they can do so by moving horizontally over to them. If they are interested in finding out about more than one establishment in a given
area, they can obtain a list of other establishments inthe area to choose from by clicking on the background image.
An enormous amount of calculation is required toarrange hundreds of thousands of items for bird’s-eye
viewing within the screen space and allow them to be
moved around within the area. To reduce the contentdisplay calculation required, High Choukan acquires
and displays on the screen only the minimal background images necessary, i.e., those needed to synthesize into image form the contents and the background space where they are allocated. This greatly
reduces the amount of calculation needed for zoom
and pan operations, even when the number of contents is extremely large. It also enables contents to be
moved and displayed while converting synthesizedbackground images into various different scaleddown forms. Figure 6 shows the layered structure of
background images, in which the images are structured in upper and lower scaled-down forms. Fromamong these images, the ones necessary for the user’s
position in the space are selected and displayed.
5. Future developments
We intend to research methods of clustering not
only news articles but also blog articles to enhance
the targetability of topic words extracted using thelatest topic word extraction technique. Since blog
topics are extremely useful in corporate marketing
activities, we will also attempt to expand the usage ofblog topic correlation and various other analysis
parameters. As for display interfaces, we will strive
to develop interfaces for displaying blogs, message
boards, and other contents showing a significant
inter-relationship among topics.

Zoom-in

Map of Tokyo
Pan

Selection/
perusalClick

Map data courtesy of Zenrin Co., Ltd.

Fig. 5. Example screen constructed using High Choukan.

32

NTT Technical Review

Special Feature

Upper
scaled-down
form

User’sscreenareaLower
scaled-down
form
Only the background image at the edgesof the screen is visible.

Fig. 6. Layered structure of background images.

References
[1]
[2]

[3]

http://www.soumu.go.jp/iicp/chousakenkyu/data/research/survey/
telecom/2006/2006-1-01-2.pdf (in Japanese).
Y. Sato, H. Kawashima, T. Sasaki, and M. Oku, “Latest Topic Words
Detection from Chronological News Stream,” IEICE TechnicalReport, 2005-NL-168, pp. 1-6, 2005 (in Japanese).
S. Miyahara, T. Sadakata, and M. Oku, “Navigation Interface that
Uses Prosperity of Other Users Intended for Several 100,000 Contents,” IEICE Technical Report, 2005-HIP-49, pp. 159-162, 2005 (inJapanese).

Yoshihide Sato
Research Engineer, Media Computing Project,
NTT Cyber Solutions Laboratories.
He received the B.E. degree in electrical andelectronics engineering and the M.E. degree in
informatics from Kyoto University, Kyoto, in2000 and 2002, respectively. He joined NTT in2002. His current research interests include blog
mining, document clustering, and keywords
identification. He developed the extractor of latest topic words in the HotWindow+ system.

Hidenori Okuda
Senior Research Engineer, Supervisor, Media
Computing Project, NTT Cyber Solutions Laboratories.
He received the B.E. and M.E. degrees in precision machinery engineering from the University of Tokyo, Tokyo, in 1986 and 1988, respectively. He also received the M.S. degree in computer science from Stanford University in 1994.
In 1988, he joined NTT Human Interface Laboratories and mainly engaged in R&D of visualcommunication systems. From 1997 to 2003, heengaged in multimedia business development in
the business sections of NTT and NTT-ME. He iscurrently interested in techniques for mining
information from voluminous consumer-generated media. He is a member of the Institute ofElectronics, Information and Communication
Engineers (IEICE) of Japan and the Institute of
Image Information and Television Engineers.

Harumi Kawashima
Senior Research Engineer, Media Computing
Project, NTT Cyber Solutions Laboratories.
She received the B.E. and M.E. degrees incomputer science engineering from Yamanashi
University, Yamanashi, in 1988 and 1990,
respectively. Since joining NTT Human Interface Laboratories in 1990, she has mainly been
engaged in R&D of communication and information systems. She is a member of IEICE.

Vol. 4 No. 8 Aug. 2006

Shinji Miyahara
Research Engineer, Innovative IP Architecture
Center, NTT Communications.
He received the B.E. degree in electrical, computer, and systems engineering from Hiroshima
University and the M.E. degree in information
science engineering from Osaka University,
Osaka, in 1998 and 2000, respectively. He joined
NTT Cyber Solutions Laboratories in 2000 andwas mainly engaged in interface research on theInternet. After these R&D activities, he moved to
the Innovative IP Architecture Center of NTT
Communications in 2006.

Toru Sadakata
Senior Research Engineer, Media Computing
Project, NTT Cyber Solutions Laboratories.
He received the B.E. and M.E. degrees inapplied physics from Waseda University, Tokyo,
in 1989 and 1991, respectively. In 1991, hejoined NTT Human Interface Laboratories,Tokyo. He was engaged in R&D of video handling and human interfaces. From 1997 to 2000,
he worked in NTT Printec Corporation (nowNTT Quaris), Tokyo. He was engaged in thedevelopment of a color printing system. In 2000,
he moved to NTT Cyber Solutions Laboratories.
His current research interests are contents handling and human interfaces. He is a member ofIEICE, the Human Interface Society of Japan,
and the Association for Computing Machinery.

33