Mobility(Data( Management(&(Exploration( ( I.#Introduction#

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Junior Newton
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(University(of(Piraeus( (Greece( infolab.cs.unipi.gr( ( 2013.

1 Mobility(Data( Management(&(Exploration( ( I.#Introduction# Yannis&Theodoridis&&&Nikos&Pelekis& InfoLab( (University(of(Piraeus( (Greece( infolab.cs.unipi.gr( ( ( Τα πάντα ρει, µηδέποτε κατά τ αυτό µένειν Everything changes, nothing remains still Heraclitus (500 BC) 2#

FP7/SEEK((hNp://www.seekOproject.eu),(2012O15( " FP7/DATASIM((hNp://www.datasimOfp7.

org),(2009O12( " FP6/GeoPKDD((hNp://www.geopkdd.eu),(2005O09(!

Discovery & Delivery 3# Previous#versions#of#this#material# " 2013(! PhDOlevel(seminar(@(JRC,(IsrpaOItaly,(Apr.(2013( " 2012(!

2 Acknowledgments#! The(content(of(this(lecture(series(has(been(inspired( by(collaborabve(work(done(in(the(following(eu( projects:(( " FP7/SEEK((hNp:// " FP7/DATASIM((hNp:// " ESF/COSTOMOVE((hNp://moveOcost.info),(2009O13( " FP7/MODAP((hNp:// " FP6/GeoPKDD((hNp:// Also,(special(thanks(to(InfoLab(members( GeoPKDD Geographic Privacy-aware Knowl. Discovery & Delivery 3# Previous#versions#of#this#material# " 2013(! " 2012(! " 2011(! " 2010(! More(details(at:(hNp://infolab.cs.unipi.gr/( 4#

3 Introduction,#Overview# From digital mapping to mobile social networking A tour on geospatial information management challenges 5# Mobile#devices#and#services#! Large(diffusion(of(mobile(devices,(mobile(services(and(locaBonObased( services(#(loca3on4&and&mobility4aware&data& 6#

4 Which#data?#! LocaBon(data(from(mobile(phones(( " i.e.,(cell(posibons(in(the(gsm/umts(network(! LocaBon((and(trajectory)(data(from(GPSOequipped(devices( " Humans((pedestrians,(drivers)(with(GPSOequipped(smartphones( " Vessels(with(AIS(transmiNers((due(to(mariBme(regulaBons()(! LocaBon(data(from(indoor(posisBoning(systems( " RFIDs((radioOfrequency(ids)(( " WiOFi(access(points( " Bluetooth(sensors( 7# GPS#Data#! Raw(data:(GPS(recordings( objectid, trajectoryid, timestamp, longitude, latitude ,1, :54:07, , ,1, :54:25, , ,1, :55:06, , ,1, :55:56, , ,1, :56:16, , ,1, :19:26, , ,1, :19:36, , ,1, :19:45, , ,1, :19:55, , ,1, :20:05, , #

GPS#Data# " Q:(where(is((24.6071983243782,(38.0084733198281)(located(?( " A:(in(the(short(sea(passage(between(Euboea(and(Andros(islands,( Greece( 9# What#is#a#(GPSKbased)#trajectory?#!

5 GPS#Data# " Q:(where(is(( ,( )(located(?( " A:(in(the(short(sea(passage(between(Euboea(and(Andros(islands,( Greece( 9# What#is#a#(GPSKbased)#trajectory?#! A(trajectory(is(a(model(for(a(moBon(path(of(a(moving(object( (human,(animal,(robot,( )( " (due(to(discrebzabon)(a(sequence(of(sampled(bmeostamped(locabons( (p i,(t i )(where(p i (is(a(2d(point((x i,(y i )(and(t i (is(the(recording(bmestamp(of(p i ( 10#

6 What#is#a#(GPSKbased)#trajectory?#! A(common(representaBon(in(MOD(is(a(3D&polyline&where(verBces( correspond(to(bmeostamped(locabons((p i,(t i )(( " Usually,(linear&interpola3on(is(assumed(between((p i,(t i )(and((p i+1,(t i+1 )( (p i,t i ) (p i+1,t i+1 ) 11# From# raw #to# semantic #trajectories# raw&mobility&data& sequence&(x,y,t)&points& e.g.,&gps&feeds& meaningful&mobility&tuples& <place,&3me in,&3me out,&tags>& [8am, 9am] [6pm, 6:30am] [7:30pm, 8pm] Road (bus) Train (metro) Sideway (walk) Home (breakfast) office (work) Market (shopping) Home (relax) [~, 8am] [9am, 6pm] [6:30pm, 7:30pm] [8pm,~] Semantic Trajectory: T={e first,,e last } Episode: e i = (STOP MOVE, t from, t to, place, tag) 12#

5(million(GPS(recordings(#(~4,500(trajectories( 13# IMIS3days

7 Examples#of#GPS#trajectory#data#! Amki (dataset:(vehicles(moving(in(athens(metropolitan(area( " ~1.5(million(GPS(recordings(#(~4,500(trajectories( 13# Examples#of#GPS#trajectory#data#! IMIS3days (dataset:(vessels(sailing(in(mediterranean(sea( " (only(a(small(subset(of(the(dataset(at(hand)(( ~3(million(GPS(recordings(from(933(vessels(during(a(3(days(period(#( 1500(trajectories( 14#

Background#on## Positioning#technologies# 15# GeoKpositioning#! PosiBoning(technologies((all(standardized(in(early(2000 s)( " Using(the(mobile(telephone(network(!

8 Background#on## Positioning#technologies# 15# GeoKpositioning#! PosiBoning(technologies((all(standardized(in(early(2000 s)( " Using(the(mobile(telephone(network(! Time(of(Arrival((TOA),(UpLink(TOA((ULOTOA)( " Using(informaBon(from(satellites(! Global(PosiBoning(System((GPS);(Assisted((AOGPS);(DifferenBal(GPS((DOGPS)( source: ESA 16#

9 SatelliteKsupported#positioning#! GPS((Global(PosiBoning(System)( " Fully(operaBonal(since(1994( " 24Osatellite(constellaBon(! monitored(by(5(monitoring(stabons(and(4(ground(antennas;(handled(with( (extremely(precise)(atomic(clocks(! At(least(5(satellites(are(in(view(from(every(point(on(the(globe( " GPS(receiver(gathers(informaBon(from(4(( (or(3,(the(minimum)(satellites(and(( (a)(triangulates(to(posibon(itself;(( (b)(fixes(its((nonoatomic)(clock( " PosiBon(accuracy:(~20m( 17# GeoKpositioning#(cont.)#! GPS(accuracy(improvements( " Assisted&GPS&(A4GPS):(provides(preOcalculated(satellite(orbits(to(the( receiver;(accuracy(~10m( " Differen3al&GPS&(D4GPS):(combines(with(land((antennas)(informaBon;( accuracy(down(to(1m( 18#

Galileo((EU)(O(fully(operaBonal(by(2019(!

Beidou((China)(O(fully(operaBonal(by(2020(!

10 GeoKpositioning#(cont.)#! GPS(compeBtors( " Glonass((Russia)( (currently,(semiooperabonal((! 24Osatellite(constellaBon;(1O10m(accuracy( " Galileo((EU)(O(fully(operaBonal(by(2019(! 30Osatellite(constellaBon;(1m(accuracy( " Beidou((China)(O(fully(operaBonal(by(2020(! 35Osatellite(constellaBon;(10m(accuracy( 19# LocationK#and#MobileKaware# Applications#...# 20#

11 DeYinitions#! (source:(swedberg,(1999)(mobile&loca3on&system&(mls)&is(a( locabon(system,(including(applicabons,(that(( " determines(the(geographic(posibon(of(mobile(subscribers(and(( " provides(them(with(relevant(informabon(and(services(! (source:(wikipedia)(a(loca3on4based&service&(lbs)&in(a(cellular( telephone(network(is(a(service(provided(to(the(subscriber(based(on( her(current(geographic(locabon( 21# LocationKbased#Services#&#Tools#! NavigaBon((vehicle(or(pedestrian)(&(InformaBon(services( " RouBng,(finding(the(nearest(pointOofOinterest((POI)( " LocaBonObased(yellow(pages(( whatoisoaround,( )(! Resource(management(&(Tracking(apps( " (taxi,(truck,(etc.)(fleet(management,(administrabon(of(container(goods,( locabonobased(charging( " Tracing(of(a(stolen(car,(locaBng(persons(in(an(emergency(situaBon,( (! Social(networking(apps( " Google(LaBtude,(Facebook(places,(Foursquare,(etc.( 22#

LocationKbased#Services#&#Tools#(cont.)#!

(( (suggests(the(opbmal(way(to(move(there((router)(!

EO911((US),(EO112((EU),(EO119((Japan)(emergency(( call(numbers( "

12 LocationKbased#Services#&#Tools#(cont.)#! FindOtheONearest( " finds(the(nearest(point(of(interest((poi)(o(restaurant,(gas(stabon,(etc.(( (suggests(the(opbmal(way(to(move(there((router)(! opbmal (in(terms(of(minimum(distance((driving(mode)(( or(minimum(bme((walking(mode)(! EO911((US),(EO112((EU),(EO119((Japan)(emergency(( call(numbers( " mandates(require(locabng(the(caller(within(( a(few(meters((150(feet,(by(fcc(regulabon)( " (in(us)(eo911(call(centers(receive(15,000(calls(from(cellular(phones(per( day( 23# LocationKbased#Services#&#Tools#(cont.)# Google My Tracks Walktastic by runtastic 24#

13 LocationKbased#Services#&#Tools#(cont.)# RunKeeper 25# LocationKbased#Services#&#Tools#(cont.)#! Tracing(lost(or(stolen(products( " Lost(smartphones:( Find(my(iPhone,( Where s(my(droid (etc.( " Stolen(cars:( Volvo(connecBvity ( 26#

Google&places:(Rate(and(share( places(on(google(!

14 LocationKbased#Services#&#Tools#(cont.)#! ( ( See(in(real(Bme(where(your(friends(( are!((launched(feb.09(by(google)( 27# LocationKbased#Services#&#Tools#(cont.)#! Google&places:(Rate(and(share( places(on(google(! Google&places&for&business:(( " (business(perspecbve)(get(your( business(found(on(google( " (end(user s(perspecbve)(rate( products,(search(for(similar,(compare( prices,(etc.( 28#

15 LocationKbased#Services#&#Tools#(cont.)# " Tag(yourselves(and(find(( tagged(friends( " Tell(your(friends(where(you(are,(( suggest(places,(etc.( 29# What#can#we#do#with#/#learn#from# mobility#data#...# 30#

16 Querying#with#vehicles#datasets #! (global)(traffic(monitoring( " How(many(cars(are(in(the(ring(of(the(town?( " Once(an(accident(is(discovered,(immediately(send(alarm(to(the( nearest(police(and(ambulance(cars( 31# Querying#with#vehicles#datasets #! (personalized)(locabonoaware(queries( " Where(is(my(nearest(Gas(staBon?( " What(are(the(fast(food(restaurants(within(3(miles(from(my(locaBon?( " Let(me(know(if(I(am(near(to(a(restaurant(while(any(of(my(friends(are( there( 32#

17 Querying#with#vessels#datasets #! Querying(and(mining(trajectories:( " Extract(/(draw(the(ship(tracks((detailed(vs.(simplified)(( " Calculate(average(and(minimum(distance(from(shore;(where(and(when( " Calculate(the(number(of(ships(in(the(vicinity(of(the(ship((e.g.(10(n.m.( radius)(( " Find(whether((and(how(many(Bmes)(a(ship(goes(through(narrow( passages(or(biodiversity(boxes(( " Calculate(the(number(of(sharp(changes(in(direcBon( " Find(ships(following(typical(routes(vs.(outliers( 33# Querying#with#vessels#datasets # ApplicaBonO(oriented(analysis:(! Improving(safety( " Analyze(the(accuracy(of(data(provided(by(base(staBons(! Traffic(opBmizaBon( " Calculate(metrics(from(the(traffic:(traffic(density,(mean(distance(between(ships,( number(of(trajectories(that(are(close(to(the( opbmal (departure( (arrival(path( " Devise(new(sea(routes(to(handle(traffic(increase( " Measure(the(acBvity(of(each(ship:(number(of(intermediate(stops(! Environmental(consideraBons( " Compare(trajectories(with(environmental(consideraBons((fuel(consumpBon,( noise(pollubon),( 34#

#more#ambitious:## Patterns#over#trajectory#datasets#!

(2007]( " Hot&mo3on&paths(( [Sacharidis(et(al.(2008]( Convoys(( [Jeung(et(al.(2008]( Centroid&trajectories(( [Pelekis(et(al.

(2005]( δt Flocks&&&Leaders(( [Benkert(et(al.(2008]( Y X T1 T2 T3 35# Back#to#LBS#discussion#! According(to((Gratsias(et(al.

18 #more#ambitious:## Patterns#over#trajectory#datasets#! Examples(of( mobility(panerns ( " " " " " " Hot4spots((popular(places)(( [Giannom(et(al.(2007]( " T4PaRerns(( [Giannom(et(al.(2007]( " Hot&mo3on&paths(( [Sacharidis(et(al.(2008]( Convoys(( [Jeung(et(al.(2008]( Centroid&trajectories(( [Pelekis(et(al.(2009O10]( ε T Typical&trajectories(( [Lee(et(al.(2007]( Moving&clusters(( [Kalnis(et(al.(2005]( δt Flocks&&&Leaders(( [Benkert(et(al.(2008]( Y X T1 T2 T3 35# Back#to#LBS#discussion#! According(to((Gratsias(et(al.(2005;(Frentzos(et(al.(2007)( Reference& object& (user)& & Database&& objects( sta3onary& mobile& sta3onary( mobile( whatoisoaround( roubng( ﬁndOtheOnearest( ((guideome( (ﬁndOme( (getotogether( Almost every current commercial app is classified as stationary-stationary!! 36#

19 Routing#! ( Get(DirecBons (in(google(maps)(! Find(the(opBmal(route(from(a(departure(to(a(desBnaBon(point(( " Goal(to(be(opBmized:(the(minimal(network(distance(traveled(or(the( minimal(traveled(bme(or( ( Live example: Get from Uni. Piraeus to Acropolis Museum: Relates(to(the(wellOknown(( shortest&path&(sp)&problem(from(( graph(theory(and(network(analysis( " Several(offOtheOshelf(soluBons,(e.g.(( Dijkstra s(singleostart(sp(algorithm( 37# Routing#(cont.)#! Relates(to(the(wellOknown(shortest(path((SP)(problem(from(graph( theory(and(network(analysis( " Several(offOtheOshelf(soluBons,(e.g.(Dijkstra s(singleostart(sp(algorithm( " Example(of(Dijkstra s(sp:(( find(the(sp(from(a(to(d ( 38#

20 Routing#(cont.)# 39# WhatKisKaround#! ( Search(nearby (in(google(maps)(! Retrieve(and(display(all(POI(located(in(the(surrounding(area( (according(to(user s(locabon(or(an(arbitrary(point)( " Area(could(by(rectangular(or(circular(or(of(any(other(shape( " Example:( Provide(me(all(the(gasOstaBons(and(ATMs(within(a(distance( of(1km ( " It(is(as(simple(as(a(typical(range(query!(! Recall(the(slides(about(range(query(processing(using(ROtrees!( Live example: Search for hotels around Acropolis museum: 40#

21 WhatKisKaround# 41# FindKtheKnearest# (not(supported(by(google(maps!)(! Retrieve(and(display(the(nearest(POI((restaurants,(museums,(etc.)( with(respect(to(a(reference(locabon(( " Example:( find(the(two(restaurants(that(are(closest(to(my(current( locabon (or( find(the(nearest(café(to(the(railway(stabon ( " Issue:(distances(are(computed(wrt.(the(network(rather(than(the(free( space((euclidean(distance)( How about getting the 1-nearest hotel wrt. Acropolis museum? (! StateOofOtheOart(algorithm((at(the(spaBal(database(domain):( " Euclidean&Restric3on ((Papadias(et(al.(2003)( 42#

22 FindKtheKnearest# Closest wrt. Euclidean distance Closest wrt. network distance 43# FindKtheKnearest#(cont.)#! Euclidean(RestricBon( " 1 st &step:&find&object&p1&which&is&nearest&to&q&wrt&euclidean&distance&& " 2 nd &step:&d1&is&the&network&distance&between&p1&and&q& 44#

23 FindKtheKnearest#(cont.)#! Euclidean(restricBon( " 3 rd &step:&retrieve&all&points&(pi)&with&euclidean&distance&from&q&less&than&d1&& " 4 th &step:&among&all&pi,&find&the&one&with&the&minimum&network&distance&from& Q& 45# Advanced#LBS#! Examples(! Constrained&rou3ng&(advanced(wrt.(geometry(/(complexity)& " alternabve(names:(inoroute(findotheonearest((frentzos(et(al.(2007),( tripoplanningoquery((li(et(al.(2005)(! Get4together (or( Find4me ((mobon(is(involved)& " See(also(Google(LaBtude,(etc.(( 46#

24 Constrained#routing#! Find(the(opBmal(route(from(a(departure(to(a(desBnaBon(point( ( " (with(the(extra(constraint(to(pass(through(one(among(a(specified(set( of(candidate(points( " Example:( provide(me(the(best(route(office(to(home(constrained(to( pass(from(a(bank(atm( ( 47# Constrained#routing#! Any(idea(for(pruning?( 48#

25 Constrained#routing#(cont.)#! VariaBon(of(Euclidean(RestricBon( " 1 st &step:&retrieve&the&op3mal&route&r&between&p&and&q& 49# Constrained#routing#(cont.)#! VariaBon(of(Euclidean(RestricBon( " 2 nd &step:&retrieve&the&euclidean&nn&w.r.t.&route&r&(point&n1)& 50#

26 Constrained#routing#(cont.)#! VariaBon(of(Euclidean(RestricBon( " 3 rd &step:&calculate&network&distances&d1=net_dist(p,n1)&and& D2=Net_Dist(N1,Q)& 51# Constrained#routing#(cont.)#! VariaBon(of(Euclidean(RestricBon( " 4 th &step:&retrieve&all&candidate&objects&(ni)&with&total&euclidean&distance& from&both&p&and&q&less&than&&d&=&d1&+&d2& Circumference Perpendicular bisector 52#

27 Constrained#routing#(cont.)#! VariaBon(of(Euclidean(RestricBon( " 5 th &step:&for&each&n i,&calculate&d1 i &=&Net_Dist(P,N i )&and&d2 i &=&Net_Dist(N i,q),& and&report&the&n i &the&one&that&minimizes&d i &=&D1 i &+&D2 i& 53# GetKtogether #(or# Find#me )#! A(number(of(moving(objects(try(to(meet(a(moving(object( " Think(of(a(live(version(of(the(popular(Pacman(game(!!( " Could(be(an(advanced( Google(LaBtude (or( Facebook(Places (app(! Methodology:( " other(objects(are(routed(to(a(point(where(( the(target(object(is(esbmated(to(arrive(( a er(a(bme(interval( " this( meebng(point (is(periodically(( refreshed( 54#

28 GetKtogether#(cont.)#! Challenge:(future&loca3on&predic3on(!!( 55# Summarizing# #! So(far,(we ve(seen(a(variety(of(mobileoaware(applicabons( " From( smart ((updated(in(realobme)(roubng(to(mobile(social( networking((google(labtude,(facebook(places,(etc.)(! Internally((either(at(server(or(client(side),(what(kinds(of(opera3ons( should(be(efficiently(supported?( " Core(database(/(computaBonal(geometry(operaBons( " GraphObased(operaBons( " Trajectory(management(operaBons( 56#

29 Operations#to#be#supported#! Core(database(/(computaBonal(geometry(operaBons( " Window&search:(selects(points(within(a((circular(or(rectangular)( window( " k4nn&search:(selects(the(ko(nearest(points(to(an(object((point(or( region)( " Euclidean&distance&calcula3on:(calculates(the(Euclidean(distance( between(two(points( " Path&length&rou3ne:(calculates(the(length(of(a(path(! GraphObased(operaBons(! Trajectory(management(operaBons( 57# Operations#to#be#supported#(cont.)#! Core(database(/(computaBonal(geometry(operaBons(! GraphObased(operaBons( " Rou3ng:(finds(the(opBmal(route(between(two(points((taking(into( considerabon(a(number(of(constraints)( " Network&distance&calcula3on:(calculates(the(network(distance( between(two(points( " Network&k4Nearest&Neighbor&search:(searches(for(the(kONN(of(a(point( with(respect(to(network(distances(! Trajectory(management(operaBons( 58#

30 Operations#to#be#supported#(cont.)#! Core(database(/(computaBonal(geometry(operaBons(! GraphObased(operaBons(! Trajectory(management(operaBons( " Trajectory&refresh:(adds(a(new(coming(posiBon(to(an(exisBng( trajectory( " Trajectory&projec3on:(esBmates(the(posiBon(of(an(object(at(a(future( Bme((taking(into(consideraBon(its(history)( " Trajectory4based&search:((spaBal(and/or(temporal)(window(search,(NN( search,(trajectory(similarity(search,(etc.( 59# The#big#picture# 60#

61# The#modules#of#our#architecture# raw data producers

Mobility Data Querying Raw location recordings (DB)

[6pm, 6:30am] [7:30pm, 8pm] PoI DB + (Semantic) Mobility

(metro) Sideway (walk) Home (breakfast) office (work)

[6:30pm, 7:30pm] [8pm,~] + (Semantic) Mobility Data OLAP

31 61# The#modules#of#our#architecture# raw data producers Trajectory reconstruction Semantic enrichment (Semantic) Mobility Data Querying Raw location recordings (DB) Trajectories (MOD) Semantic Trajectories (STD) [8am, 9am] [6pm, 6:30am] [7:30pm, 8pm] PoI DB + (Semantic) Mobility Data Mining Mobility Data Visualization Road (bus) Train (metro) Sideway (walk) Home (breakfast) office (work) Market (shopping) Home (relax) [~, 8am] [9am, 6pm] [6:30pm, 7:30pm] [8pm,~] + (Semantic) Mobility Data OLAP Extract- Transform- Load (ETL) (Semantic) Trajectory aggregations (DW) 62#

32 Key#questions#that#arise#! How(to(reconstruct&a&trajectory(from(raw(logs?((! How(to(store&trajectories(in(a(DBMS?( " Is(a(trajectory(simply(a(sequence(of((x,(y,(t)(tuples?(! What(kind(of(analysis&is(suitable(for(mobility(data?(( " In(parBcular,(trajectories(of(moving(objects?( " How(does(infrastructure((e.g.(road(network)(affect(this(analysis?(! Which(paRerns&/&models&can(be(extracted(out(of(them?( " Clusters,(frequent(paNerns,(anomalies(/(outliers,(etc.( " How(to(compute(such(paNerns(/(models(efficiently?(! How(to(protect&privacy&/&anonymity?( " Looking(for(the(tradeOoff(between(privacy(protecBon(and(quality(of(analysis( 63# Course#outline# I.&Introduc3on& (( DefiniBon(of(trajectory(data;(GeoOposiBoning(technologies;(LocaBonO aware(applicabons( II.&Background& (( SpaBal(database(management(and(exploraBon( III.&Mobility&data&management& (( Acquiring(trajectories(from(raw(data;(LocaBonOaware(querying;( Efficient(trajectory(indexing(and(storage(in(MODs( IV.&Mobility&data&explora3on& (( Trajectory(warehousing(and(OLAP;(Mobility(data(mining(and( reasoning;(visual(analybcs(for(mobility(data( V.&Privacy&aspects& (( Preserving(user(traces (anonymity( VI.&Outlook& (( Open(issues;(Future(challenges( 64#

33 Questions# 65# End(of(section#

LOCATION PRIVACY & TRAJECTORY PRIVACY. Elham Naghizade COMP20008 Elements of Data Processing 20 rd May 2016

LOCATION PRIVACY & TRAJECTORY PRIVACY Elham Naghizade COMP20008 Elements of Data Processing 20 rd May 2016 Part I TRAJECTORY DATA: BENEFITS & CONCERNS Ubiquity of Trajectory Data Location data being collected