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TRANSCRIPT
Introduction
•Mobile and communication technologies have passed trough intensive research and development in recent years.
•The results of this development have brougt new possibilities in many different areas. We can say that mobile information systems are becoming a part of our everyday life, even though that many people didn’t even come to realize.
•We have a possibility to be “mobile” during our work or leisure and withal remain in contact with our background in the office or with other workers or friends in the field. We still have almost unlimited access to information sources and computing power if necessary.
Today’s lecture…
1. Introduction to mobile technologies, their advantages and weaknesses. Some application areas – briefly.
2. More detailed acquaint with components used in mobile GIS
3. Practical examples from our group
4. Discussion, exchange of experiences
Mobile technologiesFirst look…
I.
Mobile Geoinformation Technologies
•MGIT could be characterized as IT designated for acquiring and processing of spatial data, that actively use mobile devices, wireless communications and real time knowledge of self position and position of other subscribers for problem solving.
•Technologies used for construction of MGIT are:
•Mobile computers (notebooks, PDA’s, “smart phones”)•Wireless communications (GSM,WiFi,satellites,...)•Positioning systems (global, local, radio based, inertial,…)•Software for mobile GIS – on client and server site•Geodata•Other components depending on target area
Sample scheme of MGIT
GPS sats
GSM net
Mobile clients
GIS a DB servers
InternetWorkstations
Why mobile GIS ?
• Need of work in the filed• Paper and map – non portable, not actual
Paper map is not actual at the time of print …• With MGIT we have all GIS functions (Pan, Zoom, Filter,
Search, Analyze,….)• Much better object representation compared to paper
maps – layers, scaling, customable legend• Real time positioning with connection of GNSS• Knowledge of position (and history) of other users• High currentness of layers, possibility of online
actualization and dynamic reaction on recent situation• Direct digital input of new data – less errors, easy
processing and sharing
Why mobile GIS– advantages
• Information is that what moves - not people – they may concentrate on other work, not loosing time by traveling from location to location or by using non-effective convetional communications
• Possibility of centralized real time project management, coordination and monitoring of field work, online people or vehicle tracking
• Possibility of continuous gathered data quality evaluation – dynamic modification of future steps or densification of sample grid in problematic parts (for example in DTM)
• External database access – download, upload.• …
Why mobile GIS– disadvantages
• Need to buy mobile technologies – “real” outdoor equipment is very costly.
• Need to maintain wireless communication channels – fixed payment tarifs
• Battery life/technological problems
• Sometimes limited com availability
• Training of personnel – specific control,…
Different views on mobile GIS
• Tool for data gathering in the fieldsmall company, single person,…
• Tool for data gathering in the field, data sharing and online analysis, decision support, cooperation, navigation, monitoring, accounting,….
Integration of MGIT into GIS
• I. Periodic connection of mobile computer to remote database. Cheapest solution,but we do not have „with us“ the most recent data and we also do not have a chance to get the data in the field or to send it back to our office. We also have only those functions available that are implemented in mobile client.
• II. Batch data transfers (in one or both directions) with use of wireless communication We need wireless communication technology, but we have access to more recent data – databases are synchronized during connetcion time. Use of online analysis or extrernal computing power sources remains impossible or very problematic.
Integrace MGIT do GIS
• III. Fulltime On-Line connection with background and other clients in the field. Uninterrupted connection with central database in real time. All the data are stil actual and available for other mobile or inmobile clients or other remote users.
• Use of extrenal computing powre or cooperative use (clustering) of computing power is available if needed. Also all functions and services that are on base side are accessible and ready for use.
•+ Absolute work optimization. - Price for data transfers*.
*according to used technology – you may use your own.
Some sample application areas
• Underground services – utility networks
• Water management
• Transportation and logistics
• Army
• Crisis management and rescue services
• Land management, farming,….
• …
Background and components…
II.
Mobile computers and devices
• Correct and well considered selection of mobile computing devices which will be used in the field has fundamental influence for general success of mobile geoinformation technology
• Technology must not be an obstacle – it must not disturb• There are many things to consider – for example:
what kind of work are we going to do ?for how long time do we plan to stay in the field ?in what weather conditions ?
is functionality of our mobile system critical for life or security ?
• Mostly used mobile devices are notebooks, tablet PC, handheld PC or SmartPhones
• Touch displays are very useful
A few examples…
PDA’s• Small size• Light weight• Satisfying computing power• Expandability
Compaq iPAQ’s (recent):
64 MB ROM flash64 RAM ( + CF, SD, 1 GB Microdrive)
400/600 Mhz Strong ARM CPU640/480 displaysoundcardWiFi,Bluetooth a SIR/FIR, USB, ComWeight less then 160 g
*Pictures from Compaq website.
Expandability - connectivity
• Localization of possitionGPS receivers, from WiFi or GSM net
• CommunicationWLAN (802.11)GSM (GPRS)Bluetooth,….
• Memory expansion CF, SD, memory stick cards
IBM Microdrive – up to 5 GB
• MultimediaDigital cam
TV
• And other…
*Pictures from Compaq website.
Practical experiences with PDA
Advantages
• The device is really small and „Mobile“ – fits to pocket• Computing power is very adequate – comparable to PC• All memory cards or expansions are reliable and low
cost.• Non problematic communication with GPS receivers• Relatively long life on battery• Integrated communication technologies…
Practical experiences
Problems
• Stability of OS (WinCE) - ---> LINUX• Problems while working with large datasets – slow bus • Specific and very sensitive control – needs experienced
operator• Little or missing keyboard – difficult input of attributes• Designed for indoor use !!! Humidity, frost or drops may be,
and very often are destructive• No way to replace battery for spare one (not true in most
recent models)• Completely discharged battery means fatal data loss• Costly specialized commercial mobile SW for WinCE
Linux on handhelds
Why Linux on Handhelds ?
• Because recent PDA’s are powreful HW • From digital assistant to server system !• Great support for wireless communications,
Linux is designed for network and distributed environments
• Performance, modularity, security, reliable• Its Free OS – including development tools –
absolute independence on proprietary formats + strong devel. community support
• Possibility to port a lot of free software >> >> GRASS GIS on IPAQ
Linux on PDA’s• X-window system
Integrated support for client server apps.Remote execution of applicationsEasily customizable graphic user interface
• User installation of Linux into PDA is not very easy, but well supported – there is need for some knowledge and specialized SW to flash ROM
• HP support, developers from DEC, user community• Distributions Familiar Linux, Intimate Linux and other.• Native compiling environment provided
Skiff Cluster project a Toolchain Project (cross compile)
Rugged PDA s GPS
Trimble Recon, GeoXT, GeoXM
• Correct selection for field work
Notebooks
• Bigger displays then PDA’s• More CPU power• Comfortable keyboard• Long battery life (Centrino)• Easy OS selection
• More heavy, not so “mobile”.• Not good “while walking”.• Very costly in outdoor versions
Panasonic Toughbook CF 29
• Water and dust proof, touhg
• Centrino – CPU power + long run
• Integrated communications - BT, WiFi
• COM, USB. IRDA,…
• 13.3 “ display
• 3.6 kg price 5000 USD
Tablet PC’s
• Smaller and thinner then notebooks
• Bigger then PDA… But also display…
• The same computing parameters like NTB
• Long battery life
• Touchscreen control
• Very comfortable use in the field
• Available also in rugged design
Practical example – fire rescue
GPS
GSMGPRS
GIS databases
Dispatching
Other devices
Data collectionData analysis
Data collectionLAN, WAN
Internet
Internet
Background Communication Field
Wireless communications
Wireless communications•The mostly used com. technologies of today are:
•Technologies built on GSM base•GSM genaration 2•GSM generation 2.5 – HSCSD, GPRS•GSM generation 3 – UMTS, CDMATechnologies based on GSM have an advantage of long range (global) but are under licensing (very very costly) and therefore are dependent on providers
•Technologie built on “open standards”•802.11 (Wi-Fi) (the whole group of standards)•802.16 (WiMAX)•Bluetooth•OtherNo licensing necessary for frequences, no licensing on hardware – low costs on construction, possibility to build private or “nanonetworks”•Satellite communicationsAvailable, but costly for small company use. Possibility to use amateur satellites.
Bluetooth•Radio technology of short range, personal networks
•10 m in rev. 1, up to 100m in revision 2
•Bandwidth 1 to 3 Mbps
•Recent use in mobile GIS is mostly in combination with other technologies – like connecting GPS to PDA or notebook.
•With rev.2 coming to common use we can use it for public hotspots in POI (museums, info kiosks,…)
•The name Bluetooth comes from Denmark wiking Haraldu Blĺtandovi (10 century) – which liked blueberries…
Bluetooth
GSM networks of 2G,2.5G,3G•GSM is global radio network. Terminals, BTS, GSM central.
•First concept of GSM didn’t count with data transfers at all.
•GSM 2G allows dataflow of max. 9600 bps.
•Initiative to improve GSM – „issue“ of 2.5G
•Has brought HSCSD - High Speed Circuit Switched DataHigher bandwidth trough reserved channel – up to 43200 bps – usable for batch data transfers.
•GPRS - General Packet Radio ServiceCommunication with use of shared channel – high probability of bandwidth limitation during massive use– usable for online connection with low data flows.
•3G networks CDMA, UMTS
Shared code spectrum, speeds from 512 kbps to 4 Mbps
•4G ???
WiFi networks
•Wi-Fi nets use technology based on IEEE 802.11b nebo 802.11a
•Signal range is 300 m (in buildings 50 m). With antennas up to 20 km…
•They work on open frequencies – free for public use
•802.11b up to 11 Mbps
•802.11a or g up to 54 Mbps (some proprietary up to 108 Mbps)
•Becoming standard parts of PDA’s, notebooks but even other devices like sensors etc.
•Great for mobile applications with need of high bandwidth
•Really popular in the whole world
•Very good to combine with GSM-CDMA acting as gateway
WiFi networks
•Many cities or groups of people build public networks based on this wireless technology
•For example project WILMA Wireless Internet and Location Management Architecture in which I have participated in 2002-3 has built 200 accesspoints in Trento
•Another example CZFREE.NET
•Our university buildings, campus and student dormitories are well covered
WiFi networks
• Animation
WiMAX
• 802.16 – new standard for wireless
• Range within limits up to 50 Km !!!
• Connection speeds up to 70 Mbit/s /user
• Up to 2048 users on one accesspoint
• May be combined with 802.11 a,b,g
• Will be very serious competition for GSM operators or CATV operators
Other possibilities
•Civil band radio modems
•Packet radio
•Satellite communications – Inmarsat, ….
•TETRA, MATRA – rescue services, army, police
Wireless com. security
• It is necessary to use some security precausions with public wireless
• Everyone (with necessary knowledge) may listen to your communication
• Data encryptionHardware layer – WEPNetwork layer, protocol extensions like HTTPS, SSH,…Application level
Positioning•Knowledge of client’s position is crucial for MGIT
•Accuracy is dependent on application type
•Mostly used are => GPS, GLONASS, in future Galileo – global systems
•Well known, widespreaded, very accurate with some methods
•Limited signal availability in some places– forests, towns, tunels …
•But available free of charge at global range
Methods for precising GPS
•DGPS with postprocessing
•In MGIT we need real time corrections
Distribution of corrections with use of wireless networks
RTK method – centimeter accuracy on the move
Combination of GPS and GLONASS satellites at the same time – more sats, better constellations, higher availability
•You need access to nearby DGPS station or build yours which is costly
•You may also use EGNOS system – first step of GALILEO project – correction distributed free of charge from geostationary satellites, no costs for you…
EGNOS• European Geostationary Navigation Overlay System
ground monitoring stations and cosmic segment
• It still monitors GPS and GLONASS state and calculates Ionospheric and Tropospheric models which are then distributed from geostationary satellites together with information about anomalies and failures of GNSS satellites
• Now fully operational• Form and intensity of EGNOS signal is very simillar to
GPS signals on L1 band. The reason is in easy construction of receivers capable to use this signals – becoming standard
EGNOS
Average horizontal accuracy (95%) without EGNOS and with EGNOS
Connecting GPS to mobile PC
• Cable (serial interface – COM, USB)
cables bring troubles…
• PCMCIA slot
• CF (compact flash) slot
devices stick out, may be damaged
• Bluetoothideal connection of today
GPS + PDA – practical experiences•CF GPS fPretec 12 channel receiver
•Works without problems with PDA or notebook (reduced to PCMCIA)
•Accuracy under 5 m
•Does not work in low temperatures (under 0C) – pouze v autě + anténa
•Consumes relatively much energy
•Very low price about 120 USD
Other GPS
Possitioning from GSM•Nets GSM•Massive spread og GSM + improvement of mobile terminals•There are several methods:•Methods based on knowledge of network and radio wave behaviour accuracy under 500 m
Method Cell Global Identity + time advance
Posstitoning – GSM nets
•Methods based on GSM network behaviour and MT functions
•UL-TOA (Uplink time of arrival) – evaluates signal delay from mobile phone
•Every phone has its own timer – like clock, which are synchronized with GSM network central time
•In case that the phone is in range of minimally 3 BTS stations with which it can communicate we can calculate triangulation from each time delay between phone and stations
•Very similar method to GPS.
•Accuracy under 30 meters (depending on conditions)
Possitioning – other possibilities•Possitioning from WiFi nets
Still under research but tested (WILMA) Use of neural network for temporal environment description (empty building, building full of students) – may go under 1m
•Inertial navigation sensors, accelerometers, odometers
Need correction after some time – nowadays may work for hours
Mechanical or opto-electronic base
Geodata in connection with MGIT
• We may prepare data to the field in advance and upload it into mobile device at the office – in such a case we must be very careful what to take and count with all circumstances.
• We may download data in the fieldMap server (feature server)
FTP, ….
Email,…
Geodata and MGIT• Most users are willing to use data in the field for more advanced
purposes then just looking or navigation – they want to modify the data, add new data and run some calculations over it.
• But if we have or download data from mapserver in for example S42 coordinate system we are not easily able to combine them with WGS 84 data from GPS.
• In the field there is not time for recalculations and common mobile GIS applications do not support many coordinate system transformations “on the fly”
• Therefore it is necessary to prepare the data in compatible format or in mutliple formats to have a choice – this is very important to check if you plan to use data from external data sources like mapservers etc..
Mapservers in MGIT
• Great and easy to use data source for mobile clients
• May perform two functions1. Data source2. Data source and GIS tool
• Limitation in size of PDA displays • Limited connection speeds• Limited functions of www browser on PDA (may be
solved by use of WMS, WFS client)
Mapservers in MGIT
• Animation
Software for mobile clients
•ESRI ArcPAD + ArcIMS server
•Autodesk On Site
•Intergraph Intelliwhere
•Trimble TerraSync
•BabyGRASS
•GPSDRIVE – more navigation SW
ESRI ArcPAD
•ESRI ArcPad probably the most common
•We can call it simplified ARCView
•Includes modules for communication with ARCIMS servers and also with WMS / still only download
•Support for GPS and corrections
•Is not originated to be used as full featured GIS SW – user is expected to have other ESRI products at the office for post-processing and data preparation
•Costly – 495 USD, for devel kit 1500 USD
ESRI ArcPAD
Autodesk OnSite View
• Stand alone tool for exloration of schemes, civil plans or maps, and also for
notes or measurements
• AutoCAD DWG a DXF
Autodesk OnSite View
Trimble TerraSync
• Designed for OS Windows CE• Graphical navigation• Support for ArcIMS and Open GIS map servers • Support for real-time corrections• Supports shape files• Sending data by email • Possibility to add spoken notes, pictures,..• You need to have Pathfinder Office for data
preparation and post processing
Trimble TerraSync
GRASS GIS on Pocket PC
• Lightweight versin GRASS 5.0 (2002/3)
• Compiled for prcessor SA1110 (iPAQ).• Rastr• Vector• ID points• Object identification• Distance measurements• Zoom, Pan• GPS support• Distributed database support GRASS shell on iPAQu
“Baby GRASS” demo systém - screenshoty
“Baby” GRASS demo - GUI
Tcl/Tk GRASS hlavní menu Tcl/Tk Display menu Tcl/Tk Display – Rastrové mapy
GPSDRIVE
•Open Source advanced navigation system
•GPS daemon – on IP
•Tracing of several clients
•Download of maps from WMS
•Waypionts
•Route calculation in real time
•Speed, direction
•Sound command and output
•Detection of police radars with WiFi
GPSDRIVE
?• Which mobile computer is ideal
choice for universal work in the field ?