Balog : Location-based information aggregation system
Hiroki Uematsu, Kosuke Numa, Tetsuro Tokunaga, Ikki Ohmukai, Hideaki Takeda
Yokohama National University,
79-2 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501 Japan
National Institute of Informatics,
2-1-2 Hitotsubashi, Chiyoda, Tokyo 101-8430 Japan
uematsu@nii.ac.jp
Abstract
Balog is a location-based information aggregation system with GPS-enabled mobile
phones. Balog system collects location-based
information via E-mail and RSS and represents
it either with association with maps or with theweblog style, i.e., entries near the locationdisplayed in reverse chronological order. We
also propose representation of metadata forlocation embedded in RSS and its utilization.

1 Introduction
Recently, weblog sites have been increased on theWeb. A weblog site (usually called blog) consists ofmany small entries that represent author's opinions,
ideas or something what to say. Frequent update is oneof the important characteristics of weblog site. It is easy
for users to update their weblog contents using weblog
tools such as MovableType [Six Apart]. Using of weblog
tools add the other characteristic, i.e., generating
RSS[RSS 2000] automatically.
On the other hand, most of people now have mobilephones equipped with many functions (e.g. Webbrowsing, E-mail, Digital Camera, GPS, and so on). In
particular, we focus on local information around ofmobile phone users.

Figure 1 Architecture of Balog system

In this paper, we propose location-based information
aggregation system called "Balog."1 Balog system col1

"Ba" stands for a place or a field in Japanese.

lects
location-basedinformation
createdbyGPS-enabled mobile phones with camera, and represents such information either with association with maps
or with the weblog style, i.e., entries near the location
displayed in reverse chronological order. We use mobilephones as personal input device to weblog, because
weblog users often write what happens at the current
moment and mobile phones are the most convenientdevices on such scenes.

2 Balog system
Figure 1 is the architecture of Balog system. Balogsystem mainly consists of two parts: the collection partwhich extracts location-based information from E-mailand RSS, and the representation part which visualizes
location-based information with pasting it on map orwith sorting by order data.

2.1 Collecting location -based information
First, we explain the part of collecting information.
Balog system has two ways of collecting information.
One is via E-mail with location-based information sent
by a Balog user; the other is via RSS files generated byweblog tool and collected by the Balog system.
Collecting from E-mailBalog users send E-mail to Balog system with theiraccounts. These accounts are created by Balog system. Users send an E-mail with a picture that contains
location-based information. In Balog system, subjectof E-mail is interpreted as title of weblog entry, andbody of E-mail as description of weblog entry. If theuser wants to update her/his weblog site with mobilephone, Balog system updates the weblog site automatically with the E-mail received from her/him.
Collecting from RSS
Users update their weblog sites from their PC ormobile phone. Then weblog sites generate RSS. Balog system collects RSS files from those weblog sites
and extracts information and pictures that describedin RSS.
Location data is written in Exif [EXIF] directory in aJPEG file. A GPS-enabled mobile phone can embed
location data in the JPEG file of a picture taken with adigital camera equipped with it. Balog system extracts
location data from the JPEG file and registers them in adatabase.

2.2 Weblog tool plug-in
In order to use location data in a weblog site, we developed a weblog tool plug-in. It enables the weblog site
to extract location data from JPEG files and to link
Balog system with the location data. This plug-in describes location data in RSS.

The Balog plug-in describes location data in RSS.
Using the coverage element of Dublin Core [DCMI,1999], location data are represented with geo vocabulary[RDF Geo Vocabulary ] in RSS 1.0.
As we describe location data in RSS, we can assign
location data to many types of data. For example, we canaggregate sound data and make the map of sound.
Using the based_near property of FOAF [FOAF project], we can describe the place where a user usually liveor work.
<foaf :Person><foaf:name>Hiroki Uematsu</foaf:name><foaf:based_near><geo:point><geo:lat> 35.441388888889</geo:lat><geo:long>139.622975 </geo:long></geo:point></foaf:based_near></foaf:Person>

Figure 2 blog-map

2.3 Representing location-based information
We developed applications that aggregate location-based information which are contained in otherservers. An application called “location-blog" shows
location-based information as combination of map-styleand weblog-style. Figure 2 is a snapshot of this application adopted and used in 2004 JSAI (Japanese Societyof Artificial Intelligence) conference for mainly the halland restaurant guide. In this application, location-based
data collected from RSS or E-mail are pasted on the mapat left frame. The right frame represents information fora certain area sorted by reverse chronological order.
Users can choose the area by latitude and longitude.
When accessing this application from mobile phones,
users can view the area around them. In this application,
we can view information that users posted. Whensearching information, we can use text and location data.
Various users’ impression about a certain area can beaggregated and can be looked through easily by users.
We can search information by location, because theBalog system can aggregate location-based information.
However, Balog system uses only JPEG files with location data in Exif so far. We can search only JPEG files
with entries. To search various data, we propose the way
to store location data in RSS in the following section.

3. Representation of location data in RSS
We propose the following RSS format.
<item rdf:about="http://www.Balog.jp/~hiro/mt/archives/000335.html"><title>camio</title><link>http://www.Balog.jp/~hiro/mt/archives/000335.html</link><description>….</description><dc:subject></dc:subject><dc:creator>hiro-moblog</dc:creator><dc:date>2004-06-12T17:21:41+09:00</dc:date><dc:coverage><geo:point><geo:lat>35.40828</geo:lat><geo:long>139.59548</geo:long></geo:point></dc:coverage></item>We can obtain much information about the data
posted by users to use these metadata with their accounts.
For example, there should be difference in the impression of a certain place between the users who usually
live or work there and the user who come there for the
first time. Using location-based information in RSS andFOAF, the Balog system can represent the difference ofimpression. Users can view the various viewpoint ofother users.

4. Conclusion
In this paper, we proposed the location-based information aggregation system called Balog. Balog system
consists of two parts that collects and represents location-based information respectively. We showed that
our system could aggregate and show location-based
information with various ways. In order to exploit location-based information more, we proposed the way ofdescribing location data in RSS. We believe that it will
explore more various usage of location-based information in cooperation with different systems via metadata.

References[RSS, 2000] RDF Site Summary 1.0 Specification Working
Group. RDF Site Summary (RSS) 1.0.
http://web.resource.org/rss/1.0/spec[Six Apart] Six Apart , MovableType.org
http://www.movabletype.org[EXIF] Exchangeable image file format for digital still cameras: Exif Version 2.2 2002-04, Japan Electronics and Information Technology Industries Association, JEITA CP-3451
http://www.exif.org/Exif2-2.PDF[DCMI, 1999] Dublin Core Metadata Initiative. Dublin Core
Metadata Element Set, Version 1.1: Reference Description.
http://dublincore.org/documents/dces/, 1999.
[RDF Geo Vocabulary] Dan Brickley, RDFIG Geo vocab
workspacehttp://www.w3.org/2003/01/geo/[FOAF project] The Friend of a Friend (FOAF) project

http://www.foaf-project.org/