gis guidelines data collection

Public Health Mapping GroupCommunicable Diseases Cluster

World Health Organization

Guidelines for data collection in the fieldusing Global Positioning System (GPS)

Technology

DRAFT July 2003

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Table of Contents

List of acronyms..................................................................................3

Basic Definitions..................................................................................4

1 Introduction..................................................................................5

2 General concepts...........................................................................62.1 WHAT IS GPS? ...............................................................................................................................................62.2 HOW GPS WORKS?........................................................................................................................................62.3 GPS ACCURACY.............................................................................................................................................62.4 GPS APPLICATIONS .......................................................................................................................................7

3 Recommendations.........................................................................83.1 RECENT ADVANCES .......................................................................................................................................83.2 RECOMMENDED SOLUTIONS .........................................................................................................................83.3 GPS DATA COLLECTION STANDARD...........................................................................................................9

4 GPS receivers guidelines.............................................................104.1 METHODS ......................................................................................................................................................104.2 PRE-FIELD WORK PROCEDURES ..................................................................................................................104.3 FIELD PROCEDURES .....................................................................................................................................114.4 DIGITAL MAPPING AND GIS INTEGRATION..............................................................................................124.5 SUGGESTED EQUIPEMENT ...........................................................................................................................13

5 Palm-sized PC and GPS guidelines.............................................155.1 METHOD........................................................................................................................................................155.2 PRE-FIELDWORK PROCEDURES ...................................................................................................................155.3 FIELD PROCEDURES .....................................................................................................................................175.4 DIGITAL MAPPING AND GIS INTEGRATION..............................................................................................185.5 SUGGESTED EQUIPEMENT ...........................................................................................................................20

6 Tablet PC and GPS guidelines....................................................216.1 METHODS ......................................................................................................................................................216.2 PRE-FIELD WORK PROCEDURES ..................................................................................................................216.3 FIELD PROCEDURES .....................................................................................................................................216.4 DATA COLLECTION ......................................................................................................................................226.5 SUGGESTED EQUIPEMENT ...........................................................................................................................23

Appendix 1: Comparison of hardware and software recommendedsolutions for data collection in the field.............................................25

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LIST OF ACRONYMS

GENERALDGPS differential GPSGIS Geographic Information SystemGPS Global Positioning SystemWGS84 World Geodetic System 1984

GPS MODE2D: x,y position3D: x,y,z positionDGPS 2D/3D real-time Differential GPSRTK : Real-Time Kinematic fixed or float solutionPPS 2D/3D: Precise Positioning Service

POSITION MEASURE OF QUALITYPDOP : Position Dilution of PrecisionHDOP: Horizontal Dilution of PrecisionVDOP: Vertical Dilution of PrecisionTDOP: Time Dilution of PrecisionHPE : Estimated Horizontal Position ErrorVPE: Estimated Vertical Position ErrorEPE: Estimated Position Error

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BASIC DEFINITIONSBeaconA stationary, nondirectionnal transmitter that transmits signals in all directions. In a differential globalpositioning system, the beacon transmitter broadcasts pseudorange correction data to nearby GPS receivers.The GPS receiver uses this correction to adjust the position fix calculated by the receiver. This process iscalled real-time differential correction.

Decimal degreesDegrees of latitude and longitude expressed as a decimal rather than in degrees, minutes, and seconds.

DGPSThe diffential Global Positioning System is a technique for increasing the accuracy of GPS measurementsby comparing the readings of two receivers – one roving and the other fixed at a known location.

Dilution of Precision (DOP)An indicator of satellite geometry for a constellation of satellites used to determine a position. Positionswith a higher DOP value generally constitute poorer measurement results than those with lower DOP.Factors determining the total GDOP for a set of satellites include, to name a few, Positional DOP (PDOP),Horizontal DOP (HDOP), Vertical DOP (VDOP), and Time DOP (TDOP).

Estimated Position Error (EPE)A measurement of horizontal and vertical position error, in feet or meters, based on a variety of factorsincluding DOP and satellite signal quality.

NMEA 0183A standard data communication protocol used by GPS receivers and other types of navigation and marineelectronics from National Marine Electronics Association.

NavigationThe process of travelling from one place to another and knowing where you are in relation to your desiredcourse.

PositionA unique location based on geographic co-ordinate system.

Longitudinal MeridiansA set of imaginary circles around the earth that pass through the North and South Poles. Longitudedescribes position in terms of how many degrees it is East or West of the Prime Meridian (0° longitude)called the Meridian of Greenwich.

Parallels of LatitudeA set of imaginary circles that are perpendicular to the earth’s polar axis. Latitude describes position interms of how many degrees it is North or South of the Equator (0° latitude

A WaypointIt marks an exact position fix so it can be recalled for future use. It usually indicates a town/village, ahouse, a health centre, a change of direction, an obstacle on a road etc. These positions can be put inmemory. The instrument will then be able to guide you to these points, and to give you warning at themoment you reach them.A RouteThe direction to follow to reach a destination. The route is expressed in an angular way in relation to theNorth.A TrackA previous path of travel that has been stored in a GPS receiver.Introduction

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1 INTRODUCTIONThis document aims to provide general guidelines for field data collection using theGlobal Positioning System (GPS) technology. It also describes recommended hardwareand software solutions for resource survey.

The World Health Organization has been routinely using the Global Positioning System(GPS) to map and track infectious diseases at community levels. GPS receivers are nowcommonly used by village outreach teams for onchocerciasis, guinea worm, AfricanTrypanosomiasis (sleeping sickness), lymphatic filariasis among others.

As the GPS technology is continually evolving with the advancements in technologiesand techniques, a large choice of solutions is now available for field data collection.These guidelines describes a few of the many methods for performing GPS surveys.

This document is part of the Public Health Mapping Programme effort to support therapid data collection requirements of eradication and control programmes as well as tosupport an early alert system for the rapid detection, verification, and response tooutbreaks of known, new and unexpected diseases.

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2 GENERAL CONCEPTS

2.1 What is GPS?

The Global Positioning System (GPS) is a satellite-based navigation system whichprovides exact position on the Earth anytime, anywhere, in any weather. A network of24 satellites are orbiting in space and transmit signals that can be detected by anyonewith a GPS receiver. With distance measurements from four satellites, the position on theearth is determined.

The first GPS satellite was launched by the U.S. Military in February 1978 and civillianuse began in the early 1990's. Since then receivers have decreased rapidly in price andnew uses are constantly being discovered. The GPS technology has tremendous amountof applications such as navigation, mapping and GIS data capture.

2.2 How GPS works?

The principle behind GPS is the measurement of distance between the receiver and thesatellites.

GPS satellites are orbiting in space 20 000 kilometers from Earth. The satellites areconstantly moving, making two complete orbits around the Earth every 24 hours. Eachsatellite transmits radio signals that allow a GPS receiver to estimate the satellite locationand distance between the satellite and the receiver. The receiver uses the measurementsto calculate where on or above the Earth the user is located.

With a minimum of three or more satellites, the GPS receiver can determine alatitude/longitude position. With four or more satellites, a GPS receiver can determinea 3D position which includes latitude, longitude, and altitude. By continuously updatingyour position, a GPS receiver can also provide data on your speed and direction of travel.

2.3 GPS accuracy

The accuracy of a position depends on the type of GPS receivers. Most of hand-held GPSunits are accurate to within 15 meters on average. Users can obtained much higheraccuracy by using a method called Differential GPS (DGPS). The system requires anadditional receiver fixed at a known location nearby. Observations made by the beaconreceiver are used to correct positions. DGPS method can produce an accuracy greaterthan 1 meter.

The number of satellites visible by the receiver can improve the accuracy. Some factorssuch as buildings, electronic interference or dense foliage can block signal reception andcause position errors. GPS units typically will not work indoors, underwater orunderground.

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2.4 GPS applications

Originally designed for military purpose, the Global Positioning System is now used bya large civilian community. The removal in year 2000 of Selective Availability (i.e. theintentional downgrading of civilian use of GPS by the U.S. military) has allowed the GPSto become a democratic tool. And the number of users will dramatically increase as GPSreceivers will very soon become an integral part of all mobile phones.

As GPS is usable everywhere at any time, the system has a variety of applications. Theonly limitation is the fact that it is impossible to receive the signal inside buildings orunderwater. The GPS technology is a very adequate tool for a variety of tasks forsurveying and mapping. GPS is now commonplace for navigation on land, in the air orat sea. The technology is also used for remote sensing or geodetic mapping and hasseveral applications in health and healthcare as well.

Following are some examples.- mapping and tracking infectious diseases at community levels.- collecting real-time data within the context of complex emergency situations.- assisting users in finding the nearest hospitals or clinics and even provide them drivingdirections and real-time traffic information.- helping ambulance and rescue fleet management as vehicles can be quickly andprecisely located.

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3 RECOMMENDATIONS

3.1 Recent advances

Recent advances in Global Positioning System(GPS) and mobile technology facilitatesrapid field data collection and transfer. With the introduction of Palm Pilots followed bypocket PC operating system, a new generation of handheld Personal Digital Assistants(PDA) have flooded the market. These handheld devices can be used with GPS receiversto collect information in the field. Once the location and attribute data have beencollected, all the data can be imported in Geographical Information Systems (GIS) formapping and analysis.

In addition, new mobile devices such as Tablet PC or smart phones can be GPSequipped and offer a larger choice of solutions for field data collection. New Tablet PCare now available in ruggedized versions and can be used for mapping applications inoutdoor environment. Next generation mobile phones currently entering the marketprovide users with wireless Internet access and allow them to transmit real-timeinformation on their precise location. With the avaibility of smart phones, new servicesare offered such as location-based services (LBS). In these applications geographic dataand processing are provided as a type of service over a wireless network connection.

3.2 Recommended solutions

Considering the great number of GPS receiver models and manufacturers around theworld and the recent development of new mobile devices such as Tablet PC, theseguidelines will focus on generic recommendations and a limited number of solutions.

Solution 1: GPS receiver and paper.This solution is the cheapest and is already used by differentprogrammes to map and track infectious diseases at communitylevel.

Solution 2: PocketPC and GPS.This solution is based on Windows CE operating system andArcPad as the data collection software.

Solution 3: PalmPilot and GPS.This solution is based on PalmPilot operating system andCyberTracker as the data collection software.

Solution 4: Tablet PC and GPSThis solution is based on Windows XP operating system andHealthMapper as the data collection software.

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3.3 GPS data collection standard

The positional accuracy of GPS points depends on receiver settings. For example, greateraccuracy can be achieved by keeping the rover GPS unit stationary while collectingmeasurements. Using this technique, a given GPS location is calculated as an averageof all of the position measurements, thus minimizing the effects of anomalousmeasurements. Other parameters can be set to enhance the measurement quality. Use thereceiver user’s guide to set the GPS as described below:

Static Mode A general guideline to follow for static point position is to collect data

at 1-second intervals. To collect a position measurement and, without

collecting data, take at least 10 seconds to observe the quality of the

signal (with respect to PDOP, number of satellites, etc)

Units Decimal degrees

Coordinate system Select WGS 84 (World Geodetic System).

3D Mode The receiver must be operated in a 3D mode. In this mode, itrequires simultaneous signals from a minimum of foursatellites to determine a 3D location.

DOP/PDOP Set your receiver to only collect data when the PDOP is less than 15

meters.

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4 GPS RECEIVERS GUIDELINES

4.1 Methods

Since year 2000 and the removal of the Selective Availibility, any GPS receiver canachieve an accuracy of less than 15 meters with a 95% confidence under ideal conditions.For some applications, this level of accuracy is sufficient for data collection in the fieldand GIS integration.

GPS are now commonly used by WHO for mapping population and diseases. Severalprogrammes use this technology to conduct field surveys. The system consist in enteringdata manually with forms and writing the coordinates provided by the GPS. Dataintegration in a GIS is then done by entering data with a keyboard.

The great advantage of this solution is its low cost and simplicity of use. On the otherhand this system can generate errors while collecting data.

The largest factor in the accuracy and efficiency of GPS surveys lies in how data iscollected in the field. The data capture specifications and parameters affect the resultingpositional accuracy. Efficient surveying, processing, and mapping requires that datacapture methods be well designed and rigorously followed, and the attribute datastructured carefully.

4.2 Pre-field work procedures

In order to prepare field work, it is essential to:q Prepare data capture procedure with GPS and paper. The form must be simple and

must not contain too many information to collect.q Test dowloading of GPS data on a PC and importing data in a GIS

GPS receiver+ Paper

GISDatabase

GISApplication

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q Prepare the GPS receiverFor example, the questionnaire for village baseline survey can contained the followinginformation:

- Latitude- Longitude- Village type- Population- Year of census survey- Number and types of Health Facility

A questionnaire sample can be found as one appendix of this document.

4.3 Field procedures

ü Check listItem StatusCheck battery levelsCheck the settings of your receiver. The format of coordinates must be indecimal degrees in World Geodetic System of 1984 (WGS84) datum.When collecting geographic data (villages, schools, health centres etc.) it isimportant to be as centred as possible and within a relatively open space, in orderto be able to pick up satellite signalsCheck that four satellites at least are detected and that the mode 3D is set.To mark a waypoint, it is advisable to wait one minute before writing theposition. The mean position calculated during one minute gives better result andallow to identify irregularities.

ü Collecting GPS pointsThe following are general guidelines and tips for creating a useful waypoint with anyGPS receiver.

1. Be sure you have initialized your GPS receiver according to the standards of datacollection described in the section 1. The first time a GPS unit is used in a newlocation, the unit will need up to 5 minutes to orient itself.

2. When you have located a feature you wish to record make sure you have as cleara view of the sky as possible.

3. When your GPS receiver has four satellites in view. Check your DOP/PDOPSome GPS receivers have a display labeled DOP or PDOP. This reading will giveyou an idea of how accurate your readings are. The lower the DOP/PDOP themore accurate your reading should be.

4. Record your position as a waypoint.5. Give your waypoint a record number.6. A GPS can store a number of points in its memory, but it is always advisable to

make a note of the co-ordinates and other relevant information – name of thepoint, altitude, number/code etc. – on a separate sheet dedicated to this use.

The function “mark a waypoint” must be used to capture the coordinates of your position.

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It is advisable to follow the GPS data collection standard defined in section 1.

4.4 Digital mapping and GIS integration

There are three types of features in a Geographical Information System (GIS) : points,lines and polygons. Most of GPS receivers and data logger software allow to capture thistype of objects. GPS data can be recorder in static mode for points or dynamic mode forlinear features.

You can download GPS data directly into your HealthMapper. The NMEA protocol isused to connect and transfer data to the GPS. You can read data from most of thereceivers on the market.

There are three types of GPS data which can be imported in the HealthMapper :q Waypointsq Routesq Tracks

In order to dowload GPS data into the HealthMapper, you should do the following:

q Connect the GPS to your PCq Start the HealthMapperq In the menu Tools>Extensions>Import geographic data, select the option “download

directly from GPS”q Set the GPS connection by clicking on the button “GPS parameters”. You can define

the following parameters:• Communication port. Select the port on which the GPS is connected• Baud transfert (4800 or 9600 bauds). Select this rate in relation with your GPS model.

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4.5 Suggested equipement

The GPS receiver quality will have a significant impact on positional accuracy. Severaltypes of GPS are available on the market et can be separated in three different categories:q Recreational.

The recreational GPS are the least expensive and also less accurate and cannot storedata for post-processing.

q Mapping-grade GPSThe models of GPS enhanced for mapping application are middle price. This type ofGPS offer sufficient accuracy for most GIS application.

q Survey-grade GPSSurvey grade GPS units are the most expensive and produce the highest accuracydata under the centimeter.

Mapping-grade GPS receivers are mid-range in price and provide sufficient accuracy formost GIS applications. Recreational grade receivers are the least expensive and the leastaccurate, and cannot store data for post-processing.

We will focus on recreational and mapping grade GPS. Some requirements for a goodhand-held GPS receiver are described below:

• Performance : A multi parallel channel (preferably 12 parallel channels) receiverunit

• Memory : The ability to store at least 100 waypoint positions in the receiver'smemory

• Connection with a PC : The ability to upload/download waypoints and routesto a computer (most GPS dealers have their own or will recommend software thatwill help you do this)

• The ability to store routes, especially if you are recording your movements,roads, rivers in the field. Most will allow you to store 10-20 routes.

• The receiver must have the capability to prohibit the collection of GPS data underpoor conditions. This is typically accomplished through the setting of collectionparameter masks. These masks can prevent the calculation of position fixesduring times of poor satellite geometry (PDOP) and signal strength (SNR).

• The receiver must provide processing software utilities that allow the downloadof collected data from the receiver to a PC, differential correction of the data, andexport of spatial data to GIS or database file formats.

Figure : Mapping-grade GPS

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There are several GPS makers, the most important are Garmin, Magellan or Trimble. Thetable below gives a selection of models (June 2003).

Solution PriceRange

Accuracy Datarecording

Batterylife

Memorycapacity

Garmin EtrexVistaRecreational GPS

$150 <15m No 10 hours 24 Mb

Trimble GeoExplorerMapping-grade GPS

$300 3-5m Yes 11 hours 64 Mb

Table - Proposed GPS Equipment

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5 PALM-SIZED PC AND GPS GUIDELINES

5.1 Method

GPS can be connected to palm-sized PC such as Pocket PC or PalmPilot in order tooperate field surveys. The system consist in entering data with forms and the location isautomatically saved with the GPS. During the field survey, it is possible to collect spatialand attribute data. The recording format is a standard GIS data format and make easierthe data transfer to a database.

The advantage of this solution is to reduce the risk of error in data entry and thus improvedata quality and information is immediately available in a GIS data format. A mobiledevice such as a palm-sized PC is not limited in capturing GPS points and it is the otherinterest of this tool. In some cases, positional accuracy can be improved with differentialGPS.

In opposition with a simple GPS receiver, this solution comes with a data loggersoftware. ESRI’s ArcPad software is described in the following guidelines but othersoftwares are available and some of them are free on PalmPilot.

5.2 Pre-fieldwork procedures

In order to prepare field work, it is essential to:q Prepare data capture procedure with GPS and paper. The form must be simple and

must not contain too many information to collect.q Test dowloading of GPS data on a PC and importing data in a GISq Prepare the GPS receiver

HandheldDevice+ GPS

GISDatabase

GISApplication

Internet

ClientDevice+ GPS

DataServer

ApplicationServer

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Data entry forms can be customized in a data collection software. TheESRI’s ArcPad software is a mobile GIS allowing the user to collectdata in the field. ArcPad is optimized for Windows CE and Pocket PCoperating systems. It allows to display vector and raster data and toedit data in the ESRI shapefile format. ArcPad has also GPS functionsfor real-time data capture.

ArcPad keyfeatures are the following:q Simple and easy-to-use interfaceq Standard data formatsq ArcIMS™ connectivityq display and query functionalityq editing and data captureq optional GPS plug-in capability

You can customize ArcPad interface and create data entry forms adapted to field missionusing ArcPad Application Builder. The ArcPad customization is done on a desktop PCbefore th deployment on handheld units.

You can perform the following personalization and customizationtasks:

• Create new toolbars that contain built-in and custom tools.• Design custom forms to streamline data collection in the field.• Write scripts that automate tasks and interact with ArcPad

software's internal objects.• Build applets to accomplish your organization's unique goals.• Develop extensions to support new file formats and positioning

services.

ArcPad Application Builder allows you to open a map by default at thestartup of ArcPad and to realize customized data entry form on villagesfor example.

When preparing a mission to the field with this solution, you have to take the followingmeasures before end:- Install ArcPad on a desktop computer and on a handheld computer- Prepare a ArcPad project with core layers- Prepare customization scripts in ArcPad Application Builder- Transfer the project, data and scripts on your handheld device

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ü Check list

Item StatusCheck battery levels.Check the settings of your GPS receiver. Coordinates format must be in decimaldegrees in the World Geodetic System of 1984 (WGS84) datum.When collecting geographic data (villages, schools, health centres etc.) it isimportant to be as centred as possible and within a relatively open space, in orderto be able to pick up satellite signalsCheck that four satellites at least are detected and that the mode 3D is set.To mark a waypoint, it is advisable to wait one minute before writing theposition. The mean position calculated during one minute gives better result andallow to identify irregularities.

ü Data collectionA sample ArcPad project is described below in order to illustrate GPS points collectionwith the solution. A default map is made and downloaded on a Hand held device with thefollowing layers:

q Administratives boundariesq Roadsq Riversq Lakesq Villagesq Health Centers

With a GPS receiver connected withyour handheld device, it will be possible

to collect real-time information in the field. By reading the location calculated by theGPS receiver, ArcPad alows you to create new geographic objects with the default toolsor with customized tools prepared in ArcPad Application Builder. New geographic datacan be points such as villages but also lines or polygons such as roads or districts.

Add a health center with default tools in ArcPad

1. open the ArcPad project on your handheld device2. check that the GPS signal is satisfactory3. before editing a layer on the map, check if this layer is editable in the layers list4. click on the tool to create point feature with a GPS.5. enter attributes of the new health centers in a default data entry form.

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Default data entry form in ArcPad

Add a village with a customized tool

The procedure is the same as the previous one. You only have to select the customizedtool instead of the default tool. By clicking on the map or by reading GPS coordinates,the user can add a point and collect information in a predefined format. The followingscreen shows a sample of form on village with attributes on disease and population.

Customized data entry form in ArcPad

5.4 Digital mapping and GIS integration

A shape file edited in ArcPad can be opened in most of GIS softwares and can beimported in the HealthMappper database. The file must contain a column indicating thename for each point and coordinates must be in decimal degrees in WGS 84.In order to download data collected in the field, it is necessary to complete the followingsteps:1. Connect your handheld device to your PC

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2. Download the updated file3. Start the HealthMapper4. In the menu Tools>Extensions>Import geographic data, select the option “import

points into the HealthMapper”5. Select Shapefile as a file type6. Indicate the name of the file to import. The database corresponding to the selected

country must be installed in the HealthMapper data directory.7. Select a country8. Select a category of points (Administration, Water, Education, Health). This choice

is used to fill the HierTypeCode field in the HealthMapper database.9. Select the type of points. The list varies accordingly with the selected country and

category. You can modify this list by clicking on “add a new point type”. You haveto enter the name for the type of points in english and in french. The maximumnumber of types is 9.

The wizard allows you to import a file. The operation to be accomplished is described.At the end of the process, the number of imported elements is displayed.If a record already exists in the database with the same name and the same coordinates,the system will ask you if you want to replace the record.

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Many solutions are available on the market to collect data in the field with handhelddevices or PDA. The mobile devices are GPS equipped and two main categories can beidentified according to the operating systems:q Windows CE or Pocket PC : ArcPad sofware is recommended for this kind of

environment.q Palm Pilot : There are more freewares available under this operating system. The

most popular software is OziExplorer.

Important features in selecting hardware are the following:• The equipment should be robust and reliable to support tough conditions.• The unit should have sufficient memory capacity and battery life.

We can recommend some solutions for collecting data with PDA.

Panasonic Toughbook 01 –A handheld PC adapted to field missions with a GPSmodule in option. Supports mapping and messagingapplications and features such capabilities as touch-screens, daylight readable display, and integratedwireless connectivity. It runs onWindows CE 3.0. Seewww.panasonic.com

Navman GPS Sleeve – This product is well adapted for field data collection.A GPS receiver has been developped for iPaq. It is provided withSMARTPATH GPS software containing the plans of more than 125,000cities in 13 countries. www.navman-mobile.com

Treo – This personal assistant is also a phone. A GPS card can beconnected to this product and it becomes adapted to the field datacollection. www.handspring.com

The following table gives information on suggested models (July 2003).Solution Price Accuracy Data recording Battery

lifeMemorycapacity

PanasonicToughbook 01

$1300 <15m Yes 8 hours 32 Mb

Navman GPSSleeve

$900 <15m Yes 11 hours 64 Mb

Table – Proposed GPS Equipment

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6 TABLET PC AND GPS GUIDELINES

6.1 Methods

The introduction on the market of Tablet PC offer a wider choice for collecting data inthe field. Some Tablet PC are designed for outdoor use with special screen and can beequipped with GPS.

The operating system is Windows XP for tablet PC and the HealthMapper software canbe installed directly for editing data. It is the great advantage of this solution as it canimprove data quality by reducing risks of errors in data entry and transfer. Theinformation is immediately available in the GIS software such as HealthMapper. Inaddition, a Tablet PC is powerful as a desktop PC and can be used not only for fieldmission.

6.2 Pre-field work procedures

In order to prepare field work, it is essential to:q Install HealthMapper software and database on a Tablet PC.q Test data edition.q Prepare the equipment.


Adding or updating new geographic data can be performed in the HealthMapper with theediting tools.

ü Check list

Item StatusCheck battery levels.Check the settings of your GPS receiver. Coordinates format must be in decimaldegrees in the World Geodetic System of 1984 (WGS84) datum.When collecting geographic data (villages, schools, health centres etc.) it isimportant to be as centered as possible and within a relatively open space, inorder to be able to pick up satellite signals

Tablet PC+ GPS

GISDatabase

GISApplication

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6.4 Data collection

In order to illustrate the collection of GPS points with this solution, an exemple of dataedition with the HealthMapper is described below. The database for a city or a countrycan be uploaded on a TabletPC.The extension “Editing Shapefile” in the HealthMapper allows to create or to modify ageographic file in ArcView format (shapefile). A floating toolbar can be used to editgeographic data.

Sample 1 : Add a health center1. Display the health centers you want to edit in the HealthMapper2. Activate the layer corresponding to the health centers in the legend3. Select the option “Editing Shapefile” in the menu “Tools” and select modify existing

layer4. Click with the right button on the map and enter the coordinates of the location

detected by the GPS

Sample 2 : Add a village1. Display villages in the HealhMapper.2. Activate the layer with villages in the legend3. Select the option “Editing Shapefile” in the menu “Tools” and select modify existing

layer.4. Click with the right button on the map and enter the coordinates of the location

detected by the GPS

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Some models of TabletPC are specially designed for outdoor use and can be equippedwith GPS.

Some characteristics are important when you choose a TabletPC are the following:• Ergonomics : the equipment should be robust and reliable and prepared for an

outdoor use.• The screen should be designed for viewability in daylight. Tablets PC have a

liquid crystal display of 10.4"(123 Pixel by inch), or 12.1" (106 Pixel by inch) AllLCD screens have a XGA resolution of 1024 x 768.

• Battery life L’autonomie de batterie must be sufficient but you can alwayscarry a spare battery.

• Memory You should look at the maximum memory supported : 256 Mb issufficient for a normal use. But if you need to do image processing you will need384 Mb.

• Weight vary from one to four kilos.• Hard disk capacity vary from 10 to 60 Gb.• All Tablets PC have USB2.0, FireWire (IEEE-1394) ports, a Modem 56K, a

Network card 10 /100 and WIFI (802.11).

We can recommend some models of TabletPC for field data collection.

Fujitsu Stylistic® 4000ST– a TabletPC designed for field missions with a screenviewable in outdoor conditions. To round off the solution, the Stylistic Tablet PCfeatures a choice of accessories including four docking solutions, external storage,two cases, and portable USB or wireless keyboards. See www.fujitsupc.com

Portégé Tablet 3500/3505, from Toshiba, is a reference in the domain of convertibletabletPC with a polyvalent design and excellent performances. Toshiba has equiped thePortégé 3505 with latest technologies. The result is a powerful and polyvalent TabletPC.www.tabletpc.toshiba.com

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INNOLABS EVITA2000 P-E/P-B/P-C : Premium Tablet Companion. Speciallyadapted for outdoor use with a 12 inches screen, its USB port anda DVD writer.www.innolabs.com.tw

FIC SlateVision FT 800/933 : the least expensive Tablet PC on the market and one ofthe most complete. This version has a hard disk of 20 Gb and a processor of 800 MHz.www.fic.com.tw/product/mobile/tabletpc

XPLORE iX104™-TPC : Designed, tested and verified to Military Environmental TestStandards [MIL-STD 810F], the iX104 extends the benefits of Windows XP Tablet PCEdition to go beyond the office corridor and into the field. This mobile unit is ruggedizedand is ideal for field work. www.xploretech.com

The table below gives a list of recommended models (June 2003).

Company Toshiba Fujitsu-Siemens

FIC Xplore

Product Portege3500/05

ST4000stylistic

VisionD'Ardoise

iX104

Processor Pentium III-m Pentium III-mTransmetaTM5800

Pentium III-m

Speed 1.33GHz 800MHz 1 gigahertz 866mégahertz

Ram 256MB 256MB 128MB MB 256/512Hard Disk 40 20 20 20/40Keyboard Intégré Externe Externe -Autonomy 1:38 2:34 4:30 -Weight 2 1.6 1.5 2.25Screen size 12,1 10,4 10,4 10,4Price in US$ 2,299 2,299 - 5000

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Appendix 1: Comparison of hardware and software recommended solutionsfor data collection in the field

The table below presents some technical solutions for data collection in the field usingthe Global Positioning System (GPS) technology.

Solution Garminextrex Vista

HiPac +Navman

GPS

Palm Treo Tablet PC

Price : US$ 150 US$ 1600 US$ 500 US$ 2400

Data recording No Yes Yes Yes

Accuracy : < 15 m <15 m <15 m

Battery life : 12 hours 11 hours Up to 2.5 hours talk time,150 hours standby time

4.5 hours

MemoryCapacity :

24 Mb RAM 32 Mb ROM64 Mb RAM

16 Mb 15 Gb

Data LoggerSoftware :

None ESRI ArcPad CyberTracker HealthMapper

Post-ProcessingSoftware :

HealthMapper HealthMapper HealthMapper HealthMapper

gis guidelines data collection

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