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35 ways to find your location


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35 ways to find your location.

GPS has not proved to be the panacea for finding your location. Urban canyons, price, speed, power, reliability, differing datums, and even the trustfulness of the data all contribute to a high-tech system that will not satisfy many situations when you really, really want to know your location.

This talk will explore many different ways to find a location, from using the latest technologies to low-tech hacks. These often work best when used together, to refine the accuracy or usefulness of the location data.

Measures for evaluating the different techniques will be shown, matching user needs for different scenarios to data collection types. Contexts and constraints, such as screen size and input mechanisms, will be introduced, and their effect on the various locative methods shown.

In addition to HCI issues, computers and humans require very different information to understand their locations and orient themselves. This talk will give an introduction into how people convert data into locations into psychogeography -- places, mental maps, and invisible cities.

Published in: Technology, Business
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35 ways to find your location

  1. 1. 35 ways to find your location Chris Heathcote Product experience manager Orange SA O’Reilly Emerging Technology Conference February 9-12, 2004
  2. 2. why am I here? <ul><li>in 10 years' time, </li></ul><ul><li>there will be </li></ul><ul><li>no concept of lost </li></ul><ul><li>There will come an age in the far-off years When Ocean shall unloose the bonds of things, When the whole broad earth shall be revealed Seneca </li></ul>
  3. 3. where have we come from? <ul><li>the stars, the sun </li></ul><ul><li>reading nature - birds, vegetation, wind direction, ocean swells (Polynesians) </li></ul><ul><li>follow a path or coast </li></ul><ul><li>the compass </li></ul><ul><li>the almanac </li></ul><ul><li>the astrolabe </li></ul><ul><li>the sextant </li></ul><ul><li>accurate clocks </li></ul><ul><li>the map </li></ul><ul><li>local knowledge (bushcraft) </li></ul>
  4. 4. no magic bullet <ul><li>GPS is not the solution </li></ul><ul><li>don't just throw technology at the problem </li></ul><ul><li>appreciate the toolbox </li></ul><ul><li>match needs to methods for you and your users </li></ul>
  5. 5. measures <ul><li>accuracy </li></ul><ul><li>availability </li></ul><ul><li>reliability / trust </li></ul><ul><li>output useful to humans </li></ul><ul><li>output useful to computers </li></ul><ul><li>requirements for conversion (extra enablers needed) </li></ul><ul><li>acquire or refine? </li></ul>
  6. 6. good enough <ul><li>what is good enough for your users? </li></ul><ul><li>how much benefit will they get? </li></ul><ul><li>what will it cost them? - time, money, frustration </li></ul><ul><li>most current consumer applications - 20-50m </li></ul>
  7. 7. 0. assume: The Earth <ul><li>EARTH PIC </li></ul><ul><li>accuracy: ~510 square Megametres </li></ul><ul><li>availability: until we conquer space </li></ul><ul><li>requirements: belief in a spherical Earth </li></ul><ul><li>best for: acquiring </li></ul>
  8. 8. <ul><li>the time </li></ul><ul><li>(light, dark, timezones) </li></ul><ul><li>mainly relative position of people </li></ul><ul><li>&quot;It's 3 pm here” </li></ul><ul><li>&quot;It's 7 am here” </li></ul><ul><li>easiest to use when moving long distances </li></ul><ul><li>(these days) </li></ul><ul><li>accuracy: 1000 miles (E-W) n/a (N-S) </li></ul><ul><li>availability: clocks </li></ul><ul><li>requirements: UTC </li></ul><ul><li>best for: seafaring, conf calls </li></ul>
  9. 9. 2-7. cultural clues <ul><li>which cell phone operators available? </li></ul><ul><li>which wi-fi providers? </li></ul><ul><li>phonebox operators? </li></ul><ul><li>phone number syntax? </li></ul><ul><li>newspapers available? </li></ul><ul><li>language being spoken? </li></ul><ul><li>accuracy: 1000 - 100,000 miles </li></ul><ul><li>availability: civilisations </li></ul><ul><li>requirements: up-to-date list of providers/information </li></ul><ul><li>best for: acquiring </li></ul>
  10. 10. 8. ask someone <ul><li>POLICEMAN PIC </li></ul><ul><li>accuracy: 10 metres ........ </li></ul><ul><li>availability: civilisations </li></ul><ul><li>requirements: someone who knows where they are, social interaction, a common language </li></ul><ul><li>best for: refining </li></ul>
  11. 11. 9. use a map <ul><li>maps tell stories </li></ul><ul><li>have to have a map that tells your story </li></ul><ul><li>high cognitive load - getting orientation or locating on a map </li></ul><ul><li>accuracy: 10 metres - 1 mile </li></ul><ul><li>availability: from any good bookstore (good for civilisations) </li></ul><ul><li>requirements: geolocated mapping </li></ul><ul><li>best for: refining </li></ul>
  12. 12. mobile phone location <ul><li>mainly available through network operators </li></ul><ul><li>methods often made invisible to the user and the requester </li></ul><ul><li>just different accuracy </li></ul>
  13. 13. 10. cell ID <ul><li>network reports which cell you are using </li></ul><ul><li>not always connected to nearest cell </li></ul><ul><li>can appear to move as you roam from cell to cell </li></ul><ul><li>Timing Advance </li></ul><ul><li> </li></ul><ul><li>accuracy: 50 metres - 2 miles </li></ul><ul><li>availability: cell coverage </li></ul><ul><li>requirements: network hooks </li></ul><ul><li>best for: acquiring </li></ul>
  14. 14. 11. cell ID (local lookup) <ul><li>extract cell ID from phone radio stack </li></ul><ul><li>can be used for context (home, work) </li></ul><ul><li>cell IDs reported may not correspond to available data </li></ul><ul><li>proprietary information needed for real geopositioning (or lots of collaborative mapping) </li></ul><ul><li>out-of-date / inaccurate data a problem </li></ul><ul><li>accuracy: 50 metres -5 miles </li></ul><ul><li>availability: wherever there's coverage </li></ul><ul><li>requirements: cell ID to lat/long data </li></ul><ul><li>best for: acquiring </li></ul>
  15. 15. 12. angle of arrival (AOA) <ul><li>detects angle of phone to transmitter </li></ul><ul><li>network could then use more than one transmitter to position </li></ul><ul><li>resolution not always precise </li></ul><ul><li>- can be 45 degrees </li></ul><ul><li>accuracy: 50 metres - 200 metres </li></ul><ul><li>availability: coverage </li></ul><ul><li>requirements: AOA network </li></ul><ul><li>best for: acquiring </li></ul>
  16. 16. 13. time difference of arrival (TDOA) <ul><li>times signal from handset to cell transmitters </li></ul><ul><li> </li></ul><ul><li>accuracy: 30 metres - 50 metres </li></ul><ul><li>availability: wherever there's coverage (and can find several transmitters) </li></ul><ul><li>requirements: network hooks, TDOA-enabled network </li></ul><ul><li>best for: acquiring </li></ul>
  17. 17. 14. observed time difference (OTD) <ul><li>phone times differences </li></ul><ul><li>between receiving signals </li></ul><ul><li>phone passes data to </li></ul><ul><li>network for analysis </li></ul><ul><li>accuracy: 25 - 250 metres </li></ul><ul><li>availability: coverage </li></ul><ul><li>requirements: OTD handsets/network </li></ul><ul><li>best for: acquiring </li></ul>
  18. 18. 15. assisted GPS <ul><li>assistance information produced by cell network </li></ul><ul><li>Simple GPS receiver built into phone handset </li></ul><ul><li>combines with information from one or more GPS satellites </li></ul><ul><li>needs AGPS enabled network </li></ul><ul><li>needs more hardware and software in phone </li></ul><ul><li>accuracy: 10 metres - 50 metres </li></ul><ul><li>availability: wherever there's coverage (and clear view of one GPS satellite) </li></ul><ul><li>requirements: network hooks, AGPS-enabled network, AGPS-enabled phone </li></ul><ul><li>best for: acquiring </li></ul>
  19. 19. geolocation technology
  20. 20. 16. GPS <ul><li>pretty good accuracy - at a cost </li></ul><ul><li>Selective Availability </li></ul><ul><li>can appear to move as satellites appear and disappear </li></ul><ul><li>other systems - GLONASS, LORAN-C, Galileo </li></ul>
  21. 21. GPS contd. <ul><li>needs more technology (though cost is coming down) </li></ul><ul><li>eats battery </li></ul><ul><li>needs clear line of sight to 3 or more satellites </li></ul><ul><li>- cannot be used in a building, let alone in your pocket </li></ul><ul><li>slow (for first fix) </li></ul><ul><li>accuracy: 10 metres - 75 metres </li></ul><ul><li>availability: clear view of three GPS satellites - four for elevation </li></ul><ul><li>requirements: a GPS receiver (and a few dozen satellites) </li></ul><ul><li>best for: acquiring </li></ul>
  22. 22. 17. WAAS and other GPS enhancements <ul><li>improve accuracy using other satellites, or fixed radio stations (EGNOS in Europe) </li></ul><ul><li>reports any foreseen errors in GPS, and corrects </li></ul><ul><li>could be commercialised </li></ul><ul><li>accuracy: 2 metres - 25 metres </li></ul><ul><li>availability: clear view of three GPS satellites + other data sources (satellite, radio) </li></ul><ul><li>requirements: an enhanced GPS receiver (and a few dozen satellites) </li></ul><ul><li>best for: acquiring </li></ul>
  23. 23. 18. differential GPS <ul><li>two receivers pretty close to each other (~200km) </li></ul><ul><li>signals have had same atmospheric errors </li></ul><ul><li>reference receiver is very accurately located </li></ul><ul><li>transmits errors in location to roving receiver </li></ul><ul><li>accuracy: 1-3 metres </li></ul><ul><li>availability: clear view of three GPS satellites at two locations (and communications between) </li></ul><ul><li>requirements: DGPS receivers </li></ul><ul><li>best for: acquiring </li></ul>
  24. 24. street furniture
  25. 25. 19. post codes / zipcodes <ul><li>lookup list from codes to locations </li></ul><ul><li>can be very accurate for positioning </li></ul><ul><li>proprietary data </li></ul><ul><li>goes out of date </li></ul><ul><li>only available when at a computer/phone book </li></ul><ul><li>accuracy: 10 metres to ... miles </li></ul><ul><li>availability: not when mobile </li></ul><ul><li>requirements: postcode database </li></ul><ul><li>best for: acquiring </li></ul>
  26. 26. 20. street names <ul><li>not all countries have street names </li></ul><ul><li>hard to enter when mobile (picking is best) </li></ul><ul><li>not unique </li></ul><ul><li>accuracy: 20 metres to </li></ul><ul><li>hundreds of miles </li></ul><ul><li>availability: pretty good </li></ul><ul><li>requirements: street address lookup </li></ul><ul><li>best for: acquiring or refining </li></ul>
  27. 27. 20a. street corners / intersections <ul><li>high accuracy in built-up areas </li></ul><ul><li>great for motorways </li></ul><ul><li>even provides orientation in US cities (streets and avenues) </li></ul><ul><li>accuracy: 10 metres to 5-10 miles (motorways/&quot;freeways&quot;) </li></ul><ul><li>availability: pretty good </li></ul><ul><li>requirements: street address lookup </li></ul><ul><li>best for: refining </li></ul>
  28. 28. 21. street numbers <ul><li>great - if they're available </li></ul><ul><li>need street name as well </li></ul><ul><li>accuracy: 10-100 metres </li></ul><ul><li>availability: pretty good </li></ul><ul><li>requirements: street number and address lookup </li></ul><ul><li>best for: refining </li></ul>
  29. 29. 22. business names <ul><li>databases go out of date </li></ul><ul><li>hard to enter when mobile </li></ul><ul><li>multiple locations </li></ul><ul><li>accuracy: 10 metres </li></ul><ul><li>availability: good in urban locations </li></ul><ul><li>requirements: business address lookup </li></ul><ul><li>best for: refining </li></ul>
  30. 30. 23. landmarks and littlemarks <ul><li>user picks what they can see </li></ul><ul><li>orientation from large landmarks </li></ul><ul><li>(e.g. skyscrapers) </li></ul><ul><li>maybe from street frontage photos </li></ul><ul><li>accuracy: < 1 mile - as far as the eye can see </li></ul><ul><li>availability: ok in urban locations, depends on </li></ul><ul><li>rural geography </li></ul><ul><li>requirements: landmark database and lookup </li></ul><ul><li>best for: refining </li></ul>
  31. 31. 24-26. phone boxes / public transport stops / utility markings <ul><li>bus stops, fire hydrants, </li></ul><ul><li>street lamps, traffic lights </li></ul><ul><li>proprietary data - but open for </li></ul><ul><li>collaborative mapping </li></ul><ul><li>often localised - to council or area, </li></ul><ul><li>let alone a city </li></ul><ul><li>accuracy: 10 metres </li></ul><ul><li>availability: ok in urban locations </li></ul><ul><li>requirements: access to database </li></ul><ul><li>best for: acquisition </li></ul>
  32. 32. 27. location street signs <ul><li>dedicated street signs for geolocation </li></ul><ul><li>a nice idea in principle </li></ul><ul><li>installed in London by a taxi firm (proprietary) </li></ul><ul><li> </li></ul><ul><li>accuracy: 10 metres </li></ul><ul><li>availability: bad </li></ul><ul><li>requirements: installation of street furniture </li></ul><ul><li>best for: acquisition </li></ul>
  33. 33. 28. geowarchalking <ul><li>postcode </li></ul><ul><li>street name </li></ul><ul><li>street numbers </li></ul><ul><li>lat/long graffiti </li></ul><ul><li>spray paint/sticker barcodes </li></ul><ul><li>accuracy: depends </li></ul><ul><li>availability: bad </li></ul><ul><li>requirements: crazy pirate geo-graffiti gangs </li></ul><ul><li>(Marc Smith's 2%) </li></ul><ul><li>best for: acquisition </li></ul>
  34. 34. emerging technology
  35. 35. 29. dead reckoning <ul><li>accelerometers, electronic compasses </li></ul><ul><li>highly accurate reckoning of relative position </li></ul><ul><li>needs an accurate location (and time source) to start with </li></ul><ul><li>accuracy: as good as initial lock </li></ul><ul><li>availability: everywhere </li></ul><ul><li>requirements: accelerometer and decoding </li></ul><ul><li>best for: refining </li></ul>
  36. 36. 30. wi-fi triangulation <ul><li>needs wi-fi nodes with a location server </li></ul><ul><li>needs accurate location of nodes </li></ul><ul><li>ubiquitous wi-fi is an American dream </li></ul><ul><li>used in art galleries and museums </li></ul><ul><li>At this conference - </li></ul><ul><li> </li></ul><ul><li>accuracy: 5-20m. </li></ul><ul><li>availability: bad </li></ul><ul><li>best for: refining </li></ul>
  37. 37. 31. broadcast TV/radio triangulation <ul><li>needs broadcast reception from three different locations </li></ul><ul><li>not likely in many areas (planning regulations) </li></ul><ul><li>accuracy: 50m </li></ul><ul><li>availability: ok </li></ul>
  38. 38. 32. IP lookup <ul><li>currently uninformative (normally the address of an ISP or reseller) </li></ul><ul><li>some work to make this more dynamic </li></ul><ul><li>accuracy: a country, a continent </li></ul>
  39. 39. location advertising
  40. 40. 33. encoding of location in access point name / location points <ul><li>wi-fi node advertises location through SSID </li></ul><ul><li>need a standard to be useful in more than one network of hotspots </li></ul><ul><li> </li></ul><ul><li>accuracy: 100m </li></ul>
  41. 41. 34. local servers / Rendezvous <ul><li>fixed machines advertise their location through wi-fi </li></ul><ul><li>need a standard </li></ul><ul><li> </li></ul><ul><li>accuracy: 100-300m </li></ul><ul><li>35. bluetooth </li></ul><ul><li>accuracy: 1-100m. </li></ul>
  42. 42. 36. RFID <ul><li>RFID card scanned; scanner is geolocated </li></ul><ul><li>or in reverse - card senses if scanned (and potential lookup) </li></ul><ul><li> </li></ul><ul><li>accuracy: dead - 50m. </li></ul>
  43. 43. a social future
  44. 44. 37. who you are near (inference) <ul><li>people (and people's things) reveal context </li></ul><ul><li>if one of these is geolocated, this could be used by all </li></ul><ul><li>38. objects you are near </li></ul><ul><li>your device asks others around for more-accurate locations </li></ul><ul><li>&quot;phone reports 50m accuracy” </li></ul><ul><li>&quot;wi-fi connected computer nearby reports 10m accuracy by connected GPS” </li></ul><ul><li>&quot;bluetooth node reports 5m accuracy with WAAS” </li></ul><ul><li>either pick what appears to be the most accurate, or aggregate and average the locations </li></ul>
  45. 45. 39. the road most traveled <ul><li>recording and aggregation of accurate flows </li></ul><ul><li>time, speed and quantity of movement </li></ul><ul><li>maps autogenerate themselves </li></ul><ul><li>better directions, even see which direction your friends have been or normally go </li></ul><ul><li>Amsterdam Real Time, </li></ul>
  46. 46. a few messages <ul><li>location finding helps fulfill a basic human need - security </li></ul><ul><li>technology helps - but no one technology fulfills every need </li></ul><ul><li>what happens when technology fails? </li></ul><ul><li>electronic acquisition pays no attention to geography - or the way humans think about their location </li></ul><ul><li>choose your weapons carefully </li></ul><ul><li>expect and use more than one method </li></ul><ul><li>what if you want to be lost? </li></ul>
  47. 47. questions? <ul><li>[email_address] </li></ul><ul><li> </li></ul><ul><li>presentation available from: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>Geowanking mailing list </li></ul><ul><li>#geo on </li></ul><ul><li>hope you had a good ETCon! </li></ul><ul><li>(thanks to Rael and all at O'Reilly) </li></ul>