Department of Electrical and Computer Engineering
Location-based Service for the Mobile Devices andRelated Technologies
Koji TAJIMA

Assistant Professor, Dr. Eng.
Email : ktajima@gifu-nct.ac.jp
Research Fields
Keywords

Computer System Network, Software
Mobile Computing, Location-based system, GPS● Research Outline
Theme1:A High Speed Reverse Geocoding
MethodTheme2: Security & Safety System for Elderly
by using the Cloud Services

This research proposes a high-speed reverse
geocoding method for Location-based Service. In
geocoding, the longitude and latitude become mutuallyconvertible with the “area name.” The “area name” isan address and landmark name such as “Motosu City”
and “Tokyo Tower” that are easy for the user tounderstand.

This research describes a smartphone application for
the elderly, and verifies its performance. Thisapplication provides two functions of Security & Safety
System for elderly. The elderly and its family need asmartphone to use this application. This application’s
major characteristics are as follows.

In traditional reverse geocoding methods, long
conversion time and low conversion accuracy areproblems. Our method reduces these problems by using
image-based conversion methods. First, we create“colored map images” and a “color mapping table” fora region from the vector data used in the GIS. Second,
we convert the longitude and latitude into a color codesuch as “FF00EE” using the colored map images.
Finally, we obtain the area name from the “colormapping table.” By this method, we can get the area
name from the longitude and latitude without a longcalculation time that depends on the number ofreiterated areas.
We evaluated the proposed method using the data ofa segmented ward, city, town and village of SaitamaPrefecture in Japan. As a result, we increased theconversion speed by about 70 times. In addition, wereduced the conversion error rate in comparison withthe traditional point-based conversion.

(1)This system searches an elderly’s current position
using the GPS on the smartphone.
(2)This system detects falling accident using anaccelerometer on the smartphone, and notifies its
family of the elderly person has fallen down.
(3)Using the cloud service, this system makes thepersonal information manageable by user self.
We implemented this application’s prototype andevaluate it. The prototype application works on
GALAXY NEXUS, an Android-based smartphone. For
the evaluation, we demonstrate the prototype
application in the laboratory. As a result, thisapplication show the current position of elderly, and its
measurement error is less than 10 meters. And thedetection rate of falling accident was about 96%.
Therefore, the developed application has enoughreliability. In future research, we plan to commence trial
operation with an elderly.

In future research, we plan to improve the methods
to consider the borderline of regions for high accuracy.
Additionally, we plan to analyze the practicality of ourmethod for Location-based Services.
Longitude and Latitude（S25.00, E130.00）

Coordinates in local image（302, 513）

CallEmergency call

Mapping Tableindex Area nameEurope

Favorite map

Oceania Agree

Colored separated image

Search a color mapping(0x00FFFF)

AfricaN America
Asia

Fig.1. Overview of our reverse geocoding method

Image Sharing

Settings

Fig.2 User Interface of our Application