An Example Of A Tourist Location Based Service (Lbs) With Open Source Software

Presentazione corso di Fotogrammetria

An Example Of A Tourist Location Based Service (Lbs) With Open

Source Software

M. Deidda, A. Pala, G. VaccaUniversity of Cagliari, ITALY

DISIG Department of Structural Engineering, Infrastructural and Geomatic

[email protected]

Geospatial World Forum Hyderabad 21/01/11


Contents

Introduction Definition of Location Based Service (LBS)LBS StandardsExperimentation Conclusions



Introduction

Tourism is an economic sector in constant expansion, also due to technologies and services allowing tourists to request specific information in real time, through the Internet, everywhere in the world. Among these services there are Location Based Service (LBS), which are based on the current geographic location of the user.



What is an LBS Service?Some tourists want to go to a restaurant, so they can to search it on the Internet. A better and faster way to locate it is to add further research criteria. A good choice is to add the area where the users are (position), the time when they want to eat (morning or evening) and the specific kind of restaurant they are looking for (e.g. Indian or Italian). This search can be done by using a Location Based Service .

Where? When? What? Position

“Great Wall” Chinese

RestaurantSilk Road, 45Open Fri-WedDinner only

Information



What is a LBS

The LBS is composed of 4 components.



Mobile device

A tool for the user to request the needed information to service provider. The results can be given by speeches, pictures, texts and so on. Possible devices can be PDA, Mobile Phones, Laptops......But also car navigation units or tool boxes for road pricing in a lorry.

Laptop PC

NavigatorMobile Phone

Smartphone

PDA



Communication Network

The second component is the communication network, which transfers the data from the mobile device to the service provider and vice versa. This can be a Wireless Wide Area Network (WWAN) - GSM or UMTS, a Wireless Local Area Network (WLAN) - IEEE 802.11 or a Wireless Personal Area Network (WPAN) - Bluetooth.

Network technology Average rangeData Rate

(Mbps)Frequency domain

WWAN

GSM (G2)Base station distance

100m – 35 Km

0.009 - 0.014~900 MHz, licensed

SpectrumGPRS 0.160

UMTS (G3) 2.0

WLAN

Ultra Wideband 10 m 100~2.4 & 5 GHz, not licensed Spectrum

IEEE 802.11a 50 m 54

IEEE 802.11b 100 m 11

WPANBluetooth 10 m 1 ~2.4 GHz, not licensed

SpectrumHomeRF 50 m 10IrDA (Infrared) 1-1.5 m needs line of sight 1 - 16 not licensed Spectrum



Positioning ComponentThe positioning component is used to locate the mobile device. Several positioning techniques are used in LBS; these differ from each other in positioning accuracy, Time To First Fix (TTFF), service coverage, or costs and they are classified as follows:

Hybrid

Network-based positioning

Terminal-based positioning



Service Provider

The service provider offers a number of different services to the user and it is responsible for the service request processing. Thanks to such services it is possible:- to calculate the positioning, - to find a route, - to search in Yellow Pages, - to search specific information on objects of user interest



Data Provider

Service providers will not usually store and keep all the information requested by users. Therefore, geographical database and location information data will be usually requested by authorities like mapping agencies or business partners like the Yellow Pages or traffic companies.



The LBS Standards

To perform a Location Based Service a number of different elements, from technology to data providers, have to be included. To ensure that all the different technologies and devices work together, common standards for interfaces and descriptions have to be defined.

- The ISO/TC 211 : 19132 (Location based services possible standard), 19133 (Location based services tracking and navigation) and 19134 (Multimodal location based services for routing and navigation).- The Open Geospatial Consortium (OGC): OpenLS .



The OpenLS Standard



The experimentation

The experimentation is aimed at:- studying the accuracy of the positioning component, in particular in the GPS receivers for LBS applications- performing an Info-tourist LBS application complying with the OpenLS standard and developed with Free and/or Open Source software



Positioning Component

The choice of a LBS positioning component depends essentially on two factors:1.required accuracy of the LBS kind 2.operating conditions, such as outdoor or indoor


Presentazione corso di FotogrammetriaGeospatial World Forum Hyderabad 21/01/11


The receivers used in the test are the following:

• HP iPAQ hw6915: HSGPS, 12 channels.

• GeoXT, Trimble L1, 12 channels

• Juno, Trimble L1, 12 channels



The tests have been performed in critical conditions by recreating the operating conditions of LBS terminals, such as cities (urban canyons), shopping centers (indoors), under trees, etc. These conditions cause an absence or a degradation of the GPS signals, which affect the position calculation as follows:• The receiver cannot fix the position;• The positioning accuracy is not appropriate for the specific application;• The waiting time to calculate the position is too long.



In particular, the following parameters have been studied:• Accuracy is the degree of closeness of measurements of a quantity to its actual (true) value.

• Sensitivity intended as a measure of the receiver ability to track the satellites in conditions where the signal is heavily degraded (the ability to perform the pseudo-range measurement)

• Consistency intended as the chipset ability to obtain a consistent positioning in every condition.



THE TESTTo study the parameters a path was surveyed. The path was represented by some parts where the GPS signal was in part attenuated and other where the GPS had full visibility.The path was surveyed with a sampling rate of 1 Hz.



AccuracyIn order to assess the accuracy the path surveyed is compared with the same path surveyed with greater accuracy.

Ipaq survey Juno survey



The charts show the frequency histograms, where the ordinates correspond to the

percentage of acquired GPS position within the following accuracy ranges:

• Under 1 m• Between 1 and 2 m• Between 2 and 5 m• Between 5 and 10 m

• Over 10 m (and up to a maximum of 100 m)



Sensitivity

To verify the receiver sensitivity we considered the number of receiver epochs recorded (one per second), also if in some epochs no position was available and these were compared with the acquired positions (independent of error )

Receiver expected positions

acquired positions

%

JUNO 18310 926 5

GeoXT 10303 3160 30.7

iPAQ hw6915 20714 12526 60.5



Consistency

It is the chipset ability to obtain a consistent positioning in every condition for further usages.In order to study this aspect we analyzed the percentages of positions acquired with an accuracy better than 10m (maximum allowable error for stand-alone positioning in these conditions)

Receiver % of accuracy < 10m

JUNO 90

GeoXT 96.4

iPAQ hw6915 74.5



The Info – Tourist LBS ApplicationThe LBS implemented by the Geomatics team of the University of Cagliari simulates an info-tourist service in Cagliari town centre.Infrastructure and application consist of:1. mobile device with GPS receiver and Internet network access. We used the S8000 Jet smartphone Samsung 2. Client software for the mobile device3. LBS server4. WMS (Web Map Service) and WFS (Web Feature Service) server - Geoserver5. Database of the tourist interest point.The application was developed with Free and/or Open Source software and complies with the OpenLS standard for LBS services.



In the Info-tourist LBS developed, the client sends its position and

asks to the LBS server the information on the closest tourist

point. In OpenLS terms this means to make a

ReverseGeocode operation.The answer is displayed on the mobile device together with a

map coming from the WMS and WFS Services



THE LBS SERVER

xls.py: contains the classes for interpreting the request messages and building the response messages in XLS, the XML format used in OpenLS for client-server communications

location_utility.py: implements the Location Utility Service, for the part concerning the Reverse Geocoding operation

rgc_xls.py (“Reverse GeoCode”) is a Web Application following the WSGI (Web Server Gateway Interface) standard



The LBS server: Sequence of Operations

1. The program starts by loading into memory the points of interest as a Feature Collection, and constructing a Locator object (defined in simplefeatures.py) associated to them.

2. Then it passes control to the WSGI server, which waits for requests.3. When a ReverseGeocodeRequest is received, it is interpreted for extracting

the GPS position.4. The Locator object selects from the Feature Collection the points of

interest which are nearer than a predefined search radius to the given position.

5. For each point of interest, a FreeFormAddress object is constructed and initialized with its attributes.

6. Then the address objects are encapsulated in the ReverseGeocodeResponse which is sent to the client.



The LBS Client

Based on gvSIG Mini by Prodevelop (http://www.prodevelop.es/)

Based on gvSIG (Open Source GIS by the Generalitat Valenciana)

Written in Java ME (Mobile Edition)Running on CLDC (Connected Limited Device Configuration) devices



The Map

The map used in the Web Map Service is the 1:1000 scale map of the city of Cagliari in Shapefile format.

Originally in the Roma40 national reference system, it was converted to geographic coordinates in the ETRF89 reference system.



The Database

The associated database contains all the information useful for an info-tourist LBS. In particular, the sites of historical-cultural-architectural importance have been selected, and for each of them the following data were collected:NameShort descriptionURL of a pictureURL of a Website AddressVisiting hoursTicket price



Conclusions

The LBS service developed by the research group of the University of Cagliari is currently available only to obtain information for sites of tourist interest

The research group is now implementing new functions; in particular, we are now studying the Route Service in order to calculate the route from the user’s current location to a requested point of interest.

The next step will be to develop a client also for Apple devices like IPhone and Ipad.



THANK YOU FOR ATTENTION



Positioning Accuracy

Geodetic GPS(RTK mode)

Low cost GPS(DGPS or stand-alone mode)

HSGPSA-GPS


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An Example Of A Tourist Location Based Service (Lbs) With Open Source Software