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POLITECNICO DI MILANO
Polo Territoriale di Como
Facoltà di Ingegneria dell’Informazione
Corso di Laurea Magisterale in Ingegneria Infrormatica
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OOLS FOR THE
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RELATORE: P
ROF.SSA SARA COMAI
CORRELATORE: PROF. MATTEO MATTEUCCI
TESI DI LAURA MAGISTRALE DI:
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VA
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ALI, MATR. 798044
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!Abstract!
According!to!World!Health!Organization!statistics,!over!a!billion!people,!about! 15%! of! the! world's! population,! have! some! form! of! disability! Physical! and! mobility! impairment! is! one! of! the! most! common! forms! of! disability,! which! may! be! congenital! or! a! result! of! injury,! disease! or! aging.! Physical! barriers! cause! uneven! access! to! public! services,! which! consequently! affects! the! mobility/impaired!people’s!everyday/life!quality.!
Travelling! through! cities! is! one! of! the! concerns! which! people! with! mobility! impairment! deal! with.! Regardless! of! the! necessity! of! further! enhancements! in! accessibility! of! city! routes! conditions! and! facilities,! an! adaptive!navigating!system!considering!the!needs!of!this!group!of!people!can! resolve!some!of!their!travelling!problems.!This!thesis,!as!part!of!the!Map!for! Easy! Paths! (MEP)! Polisocial! project,! aims! at! providing! a! set! of! tools! for! the! collection! of! data! over! the! travelling! experience! of! people! with! mobile! difficulties,!in!order!to!collect!their!travelling!history,!using!the!capabilities!of! smartphones,! which! are! now! available! everywhere! and! in! everyone’s! hand.! The!travelling!history!of!people!with!movement!difficulties!aids!MEP!project! to! identify! the! accessible! paths! and! provides! the! other! users! with! accessible! route!alternatives.!!
Moreover,!given!a!set!of!geo/tagged!images!taken!to!signal!the!problems! and! barriers! in! the! city! within! the! MEP! project,! this! thesis! also! seeks! for! solutions!to!compensate!their!location!data!inaccuracy.!To!this!end,!the!images! are! matched! to! the! digital! 3D! map! of! the! area,! so! that! more! accurate! and! reliable!information!about!the!physical!barriers!in!the!city!are!obtained.!!This! thesis!discusses!the!requirements!of!this!3D!map!for!accurate!localization!of! an!image!and!introduces!a!manually!constructed!3D!map!model!that!has!been! developed! for! experimental! purposes;! finally,! it! presents! an! algorithm! for! image!matching.!!
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!Sommario!
In!base!ai!dati!statistici!dell'Organizzazione!Mondiale!per!la!sanità,!più!di!un! miliardo! di! persone,! circa! il! 15%! della! popolazione! mondiale,! presenta! una! qualche!forma!di!disabilità.!Problemi!di!tipo!fisico!e!difficoltà!motorie!sono!tra! le! forme! più! comuni! di! disabilità;! queste! possono! essere! congenite! o! essere! avvenute!a!seguito!di!infortuni,!malattia!o!invecchiamento.!Le!barriere!fisiche! rendono! ineguale! l’accesso! ai! servizi! pubblici,! e! di! conseguenza! impattano! sulla!qualità!della!vita!quotidiana!delle!persone!con!mobilità!ridotta.!
Viaggiare!e!visitare!nuove!città!crea!sempre!molte!preoccupazioni!per!le! persone!con!difficoltà!motorie.!A!prescindere!dalla!necessità!di!miglioramenti! per!l’accessibilità!di!itinerari!e!di!strutture!cittadine,!un!sistema!di!navigazione! adattivo!che!consideri!le!esigenze!di!questo!gruppo!di!persone!può!risolvere! almeno! parzialmente! alcuni! dei! loro! problemi.! Questa! tesi,! svolta! all’interno! del!progetto!Polisocial!“Maps!for!Easy!Paths”!(MEP),!ha!l’obiettivo!di!fornire! una!serie!di!strumenti!per!la!raccolta!di!dati!relativi!all’esperienza!di!viaggio! delle!persone!con!difficoltà!di!mobilità,!al!fine!di!raccogliere!informazioni!sulla! storia! del! loro! viaggio,! utilizzando! le! funzionalità! offerte! dai! comuni! smartphone.! La! storia! dei! percorsi! effettuati! dalle! persone! con! difficoltà! motorie! permette! al! progetto! MEP! di! identificare! i! percorsi! accessibili! e! di! fornire!ad!altri!utenti!itinerari!alternativi!accessibili.!
Inoltre,!dato!un!insieme!di!immagini!georeferenziate!relative!a!problemi! ed! ostacoli! cittadini! raccolte! attraverso! altri! strumenti! ! del! progetto! MEP,! questa! tesi! cerca! delle! soluzioni! per! compensare! l’inesattezza! dei! dati! di! posizionamento.! A! tal! fine,! la! posizione! esatta! dei! contenuti! delle! immagini! viene! identificata! all’interno! di! una! mappa! digitale! 3D! della! zona! attraverso! tecniche!di!computer!vision,!in!modo!da!ottenere!informazioni!più!accurate!e! affidabili! sulla! posizione! delle! barriere! presenti! in! città.! La! tesi! discute! i! requisiti! della! mappa! 3D! per! la! localizzazione! esatta! di! un'immagine! e! introduce!un!modello!di!mappa!3D!costruito!manualmente,!sviluppato!a!scopi! sperimentali;! infine,! presenta! un! algoritmo! per! il! matching! dell'immagine! all’interno!della!mappa.!
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!Acknowledgment!
This!thesis!became!reality!with!the!help!and!kind!support!of!many!individuals.! Here!I!would!like!to!take!the!chance!to!extend!my!sincere!to!all!of!them.! Immeasurable!appreciation!and!deepest!gratitude!to!my!supervisor,!Prof.! Sara! Comai,! for! her! kind! and! friendly! support,! caring! guidance,! patience,! excellent!advice!and!helpful!comments.!It!is!difficult!to!overstate!my!gratitude! to! her,! so! I! just! bring! this! sentence! by! William! Arthur! Ward! saying:! “The! mediocre! teacher! tells.! The! good! teacher! explains.! The! superior! teacher! demonstrates.! The! great! teacher! inspires.”_! and! she! has! been! my! “great! teacher”.!!I! would! like! to! thank! Prof.! Matteucci,! for! being! supportive,! helpful! and! involved! in! my! thesis.! With! his! enthusiasm! and! effort! to! clarify! different! matters,!he!was!an!effective!source!of!help!to!me.!!!
I! acknowledge! the! kind! help! and! cooperation! of! Andrea! Romanoni! and! Pietro! Piazolla! in! my! thesis! for! sharing! their! knowledge! with! me.! Thanks! to! Secil! Ugur! Yavuz! for! designing! the! MEP/DL! user! interface.! And! my! special! thanks!to!my!good!friend!and!colleague,!Gianluca!Bardaro,!who!helped!me!a! lot!during!my!thesis!and!provided!me!with!part!of!his!research!results.!! I!would!like!to!give!great!thanks!to!my!best!friend,!my!greatest!motivator,! and!the!one!who!always!makes!me!believe!myself,!Ali.!He!has!been!always!by! my!side!and!his!helps!in!my!thesis!is!priceless!to!me.!!! I!wish!to!thank!all!my!friends,!who!were!always!there!for!me!and!were!a! huge!source!of!encouragement,!motivation,!and!love.!!
Lastly,! and! most! importantly,! I! wish! to! thank! my! parents,! Foroogh! and! Davood.! They! bore! me,! raised! me,! supported! me,! taught! me,! loved! me,! and! took!the!hard!times!with!me!not!being!around!them!for!the!good!of!mine.!And! to!my!dear!brother,!Kasra,!who!has!always!made!things!enjoyable!for!me.!And! indeed,! to! the! soul! of! my! grandmother! that! has! always! been! my! greatest! inspiration.!My!deepest!loves!to!her.!!To!them!I!dedicate!this!thesis.!
!!Ava!
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1
! !Table of Contents 3 !
Table!of!Contents!
!
ABSTRACT!...!I!!
SOMMARIO!...!III!!
ACKNOWLEDGMENT!...!V!!
TABLE!OF!CONTENTS!...!3!!
LIST!OF!FIGURES!...!7!!
LIST!OF!TABLES!...!11! CHAPTER!1!...!13!!
INTRODUCTION!...!13! 1.1!
THESIS!GOAL!AND!MAIN!CONTRIBUTION!...!14!
1.1!
STRUCTURE!OF!THE!THESIS!...!15!
CHAPTER!2!...!17!!
OVERVIEW!...!17!2.1
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THE!MEP!PROJECT!...!17!
2.2
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COLLECTION!OF!IMPLICIT!DATA!...!19!
2.3
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MATCHING!OF!EXPLICIT!DATA!...!21!
2.4
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THE!ISSUES!AND!NEEDS!OF!THE!MEP!PROJECT!...!23!
2.5
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THESIS!WORK!PHASES!...!24!
CHAPTER!3!...!25!!
MEPNDL:!AN!APPLICATION!FOR!THE!COLLECTION!OF!IMPLICIT!! DATA!...!25! 3.1!
INTRODUCTION!...!25!
3.2!
RELATED!WORKS!...!26!
3.2.1!
IBM!research!group5Brazil!...!26!
3.2.2!
Funf!Journal!...!27!
3.2.3!
Accessibility!maps!...!28!
3.3!
BACKGROUND!KNOWLEDGE!...!28!
3.3.1!
Smartphone!sensors!...!29!
3.4!
MEP/DL!REQUIREMENTS!...!31!
3.5!
MEP/DL!DESIGN!...!32!
3.5.1!
MEP5DL!structural!design!...!32!
3.5.2!
Interface!design!...!35!
4 Table of Contents 3.6.1
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Device!requirements!...!37!
3.6.2!
Android!manifest!permissions!...!40!
3.6.3!
User5interface!implementation!...!41!
3.6.4!
Camera!...!41!
3.6.5!
Sensors!...!44!
3.6.6!
Location!and!GPS!...!47!
3.6.7!
In5app!configuration!...!49!
3.6.8!
External!memory!management!...!50!
3.6.9!
Background!service!...!50!
3.6.10!
Notification!...!52!
3.6.11!
Saving!format!...!52!
3.7!
EXPERIMENT!...!54!
CHAPTER!4!...!59!!
3D!MAP!CONSTRUCTION!...!59! 4.1!
INTRODUCTION!...!59!
4.2!
RELATED!WORKS!...!60!
4.2.1!
Airborne!laser!scanning!...!60!
4.2.2!
Analysis!of!aerial!images!...!61!
4.2.3!
Multi5view!Stereo!...!62!
4.2.4!
Video!and!image!stream!analysis!...!62!
4.3!
REQUIREMENTS!...!63!
4.4!
DESIGN!...!64!
4.4.1!
SketchUp:!the!choice!of!program!to!construct!a!3D!map!...!65!
4.4.2!
OpenGL:!Target!Framework!...!67!
4.5!
IMPLEMENTATION!...!67!
4.6!
RESULTS!...!72!
CHAPTER!5!...!73!!
IMPROVEMENT!OF!THE!POSITION!DATA!...!73! 5.1!
INTRODUCTION!...!73!
5.2!
RELATED!WORKS!...!74!
5.2.1!
Localization!based!on!database!of!sparse!images!tagged!by!GPS! location! 74!
5.2.2!
Matching!the!street!view!image!to!the!oblique!aerial!imageries ! 75!
5.2.3!
Localization!of!image!based!on!3D!textured!models!...!77!
5.3!
REQUIREMENTS!...!78!
5.4!
DESIGN!...!78!
5.5!
IMPLEMENTATION!...!80!
5.5.1!
Capturing!Pictures!...!80!
Table of Contents 5 ! 5.5.2
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Image!Matching!...!90!
5.6!
EXPERIMENT!...!95!
CHAPTER!6!...!99!!
CONCLUSIONS!...!99!!
FUTURE!WORKS!...!100!!
BIBLIOGRAPHY!...!103! APPENDIX!A!………..111! APPENDIX!B………114! ! ! !List of Figures 7 !
List!of!Figures!
! Figure!2.1!MEP!project!scenario!...!18!
Figure!2.2!Collection!of!implicit!data!...!20!
Figure!2.3!Matching!of!explicit!data!...!22!
Figure!3.1!The!Accelerometer!axes!and!the!Gyroscope!rotation!parameters!..!30!
Figure!3.2!MEP/DL!application!structure!outline!...!32!
Figure!3.3!The!outline!of!the!MEP/DL!interface:!(a)!first!page!of!the!application! which!appears!as!soon!as!the!application!triggers;!(b)!second!page!which! follows!the!first!one:!(b)(upper)!second!page!with!the!setting!panel! hidden!and!(b)(lower)!second!page!with!the!panel!appearing;!(c)!the! detailed!interface!of!the!setting!panel!already!shown!in!(b)(lower);!(d)! notification!tab!showing!a!background!process:!(d)(left)!the!display!of!the! notification!in!the!notification!bar,!(d)(right)!!display!of!notifications!in! the!notification!drawer.!...!36!
Figure!3.4!The!overview!of!the!MEP/DL!application!developed!in!this!thesis:! (a)!StartActivity!of!the!application!developed!as!the!first!page!of!the! application!(b)!CameraActivity!of!the!application!as!the!second!page:! (b)(upper)!describes!the!buttons!functionality!(b)(lower)!shows!the! notifications,!info!button!and!setting!panel;!(c)!the!interface!outline!of!the! setting!panel,!this!panel!is!scrollable!and!contains!camera,!location,! motion!sensor,!and!position!sensor!sections;!(d)!notification!showing!a! background!process:!(d)(left)!the!display!of!the!notification!in!the! notification!bar,!(d)(right)!!display!of!notifications!in!the!notification! drawer.!...!39!
Figure!3.5!The!required!steps!to!capture!an!image!inside!of!an!Android! application!...!42!
Figure!3.6!The!required!steps!to!detect!and!record!the!sensors!information!..!45!
Figure!3.7!The!required!steps!to!catch!and!store!location!data!...!48!
Figure!3.8!The!motion!data!collected!by!MEP/DL.!This!data!is!collected!in! Lecco,!Italy.!...!54!
8 List of Figures Figure!3.9!The!NMEA!data!collected!MEP/DL!application.!The!data!is!collected! in!Lecco,!Italy!and!corresponds!to!the!motion!data!shown!in!Figure!3.10! and!position!data!shown!in!Figure!3.7!...!55
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Figure!3.10!The!position!data!collected!by!MEP/DL.!This!data!is!collected!in! Lecco,!Italy,!and!corresponds!to!the!data!shown!in!Figure!3.8.!...!55!
Figure!3.11/Schematic!representation!of!the!trajectory!reconstruction!flow!.!56!
Figure!3.12!Constructed!trajectory!based!on!the!data!collected!from!the!Como! and!Lecco!cities,!(a)!(upper)!the!plot!of!the!reconstructed!trajectory!in! Como!city,!(a)(lower)!the!reconstructed!trajectory!overlaid!on!the!path! taken!by!the!experimenter!(blue!line),!(b)(upper)!the!plot!of!the! reconstructed!trajectory!in!Lecco!city,!(b)(lower)!the!reconstructed! trajectory!overlaid!on!the!path!taken!by!the!experimenter!(blue!line)!....!57!
Figure!4.1!3D!reconstruction!of!a!map!based!on!the!model!acquired!by!the! airborne!scanners![14];!(a)!The!overlaid!3D!model,!acquired!by!airborne! scanner,!on!orthogonal!aerial!image.!(b)!The!building!reconstructed!by! extracting!the!geographical!features!of!(a)!and!projected!on!a!2D!map!for! ground!plan!acquisition.!...!61!
Figure!4.2!The!3D!model!acquisition!pipeline!using!multi/stereo!technique! [19];!(a)!The!pictures!taken!from!the!Internet;!(b)!the!mesh!made!up!of! point!cloud;!(c)!the!visibility/consistent!mesh;!(d)!the!refined!mesh!with! photo!consistency!...!63!
Figure!4.3!The!constructed!3D!models!using!the!video!streams.!(a)!Is! constructed!based!on!the!data!extracted!using!SfM!(the!picture!is!taken! from![20])!and!(b)!is!constructed!based!on!the!edge/points!extracted! from!the!scene!view![21]).!...!63!
Figure!4.4!The!flowchart!of!the!procedure!by!which!a!3D!model!of!a!piece!of! map!is!constructed.!...!69!
Figure!4.5!Images!representing!the!tasks!done!in!SketchUp!to!import!data! from!Google!Earth!and!Google!Street!View.!(a)!Represents!how!to!choose! a!piece!of!terrain!from!Google!Earth,!(b)!shows!the!added!terrain!to!the! model,!(c)!represents!the!cross!section!of!buildings!drawn!manually,!(d)! shows!how!the!volume!is!added!on!the!cross/sections,!!(e)!represents!the! panel!provided!by!Google!Street!View!at!the!closest!position!to!the!chosen! surface,!(d)!shows!how!to!chose!a!part!of!panoramic!Street!View!as!the! texture!of!a!surface.!...!71!
Figure!4.6!Lungo!Lario!Trieste,!Como,!Italy!...!72!
List of Figures 9 ! Figure!4.7!Via!Dante!Alighieri,!Como,!Italy!...!72
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Figure!4.8!Lungo!Lario!Trento,!Como,!Italy!...!72!
Figure!5.2!The!work!flow!of!Image/Capturer!process!develop!in!C! programming!language.!...!83!
Figure!3!The!geodetic!coordinates:!orange!is!LLA,!blue!is!ECEF,!and!green!is! ENU.!(The!picture!is!taken!from!Wikipedia)!...!84!
Figure!4!The!required!steps!to!transform!a!location!from!LLA!coordinate! system!to!OpenGL!coordinate!system.!(a)!Translate!the!location!from!LLA! to!ECEF,!(b)!translates!from!ECEF!to!ENU,!and!(c)!translates!from!ENU!to! OpenGL!coordinates.!...!85!
Figure!5.5!The!required!steps!to!transform!a!location!from!OpenGL!coordinate! system!to!LLA!coordinate!system.!(a)!Translate!the!location!from!OpenGL! to!ENU,!(b)!translates!from!ENU!to!ECEF,!and!(c)!translates!from!ECEF!to! LLA!coordinates.!...!88!
Figure!5.6!The!overview!of!image!matching!process!...!92!
Figure!5.7!(a)!is!the!picture!taken!from!the!real!world,!(b)!are!the!random! pictures!taken!from!the!model!in!the!5!meters!around!the!GPS!position! received!while!taking!picture!(a).!...!96!
Figure!5.8!Using!image!matching!technique,!the!pictures!taken!from!the!model! are!compared!to!the!original!image.!With!respect!to!Figure!5.7,!the!right! side!images!are!picture!(a)!in!Figure!5.7,!and!left!pictures!from!(a)!to!(e)! are!respectively!(b.1)!to!(b.7)!in!Figure!5.7.!The!matching!rate!in!all!the! pictures!except!(c)!is!equal!to!zero.!The!best!match!is!shown!in!(c).!...!97!
List of Tables 11 !
List!of!Tables!
! Table!3.1!MEP!and!MEP/DL!Features!Comparison!...!33!
Table!3.3!UI!elements!used!in!the!MEP/DL!...!41!
Table!3.4!Motion!Sensors!...!46!
Table!3.5!Position!Sensors!...!47!
Table!3.6!!Approximate!starting!and!ending!point!of!the!routs!taken!for! trajectory!reconstruction!...!57!
Table!7!BasicEngineGLFW!code!files!...!82!
Table!8!WGS84!defined!geometric!parameters!and!constants!...!85!
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Chapter!1 !
Introduction!
There!is!a!saying!“walk!a!mile!in!my!shoes”!to!see!what!another!person's!life!is! like.!Now!let’s!change!it!to!“travel!a!mile!in!my!chair”!to!see!what!wheelchair! users!face!while!they!make!their!way!around!town's!streets.!Poor!surfaces!on! footpaths,! lack! of! ramp! on! the! footpaths,! inappropriate! urban! design! and! inaccessible! transportation! services! are! among! the! basic! issues! that! people! with!mobility!impairment!are!dealing!with!during!their!everyday!lives.!!United!nations!and!some!other!independent!disability!rights!movements,! intend!to!protect!the!rights!and!dignity!of!persons!with!any!sort!of!disabilities.!! Consequently,!solving!these!sorts!of!problems!has!come!into!high!priority!in! many! countries,! and! some! accessibility! legislations! have! been! applied! on! education,! transportation,! urban! design,! and! even! public! and! private! constructions,! to! make! sure! that! there! is! an! equal! access! to! social,! political,! economic,!and!other!aspects!of!life!for!disabled!people.!!
However,! to! improve! the! quality! of! life! and! level! of! accessibility! for! people! with! impairments,! development! and! implementation! are! not! enough.! In! fact,! collecting! information! about! the! possible! obstacles! is! of! highest! importance! in! this! procedure.! In! other! words,! if! the! problems! are! unknown,! there!is!no!place!for!development!and!implementation.!So!if!information!about! problems!and!obstacles!within!cities!are!collected!regularly,!development!and! implementation! can! effectively! work! to! improve! the! quality! of! travelling! around!cities.!But,!how!to!collect!data?!How!to!guarantee!the!accuracy!of!these! data?!
14 Chapter 1. Introduction
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The! answer! could! be! obtained! by! employing! the! new! smartphone! technologies.!As!smartphones!become!more!ubiquitous!in!our!daily!lives,!it!is! becoming! more! clear! that! enrolling! the! powers! of! these! devices! can! give! a! higher! quality! data.! The! smartphone! devices’! processing! and! network! capabilities,! low! cost,! and! dimensions! is! increasing! their! popularity! and! proliferation.! In! dead,! the! new! advances! in! IC1! technology! has! changed! the! concept! of! phone! into! a! smartphone! or! a! tablet! that! may! integrate! a! MEMS2! microphone,! an! image! sensor,! a! 3/axis! accelerometer,! a! gyroscope,! an! atmosphere! pressure! sensor,! a! digital! compass,! an! optical! proximity! sensor,! an! ambient! light! sensor,! a! humidity! sensor,! touch! sensors,! and! even! more.! These! sensors! are! capable! of! providing! raw! data! with! different! levels! of! precision! and! accuracy.! Therefore,! thanks! to! the! available! hardware! sensors! embedded! in! new! smartphones! (and! tablets)! generation,! it! is! possible! to! process!the!data!collected!by!these!devices!to!increase!the!accuracy.!!
These! accurate! data! can! also! be! employed! to! generate! new! information! that!can!lead!us!to!a!better!understanding!of!the!possibilities!and!difficulties!in! using!city!facilities.!For!instance,!if!it!is!known!that!the!only!tram!accessible!for! people!with!motor!impairment!is!the!tram!number!3,!informing!this!situation,! the!people!with!mobility!difficulties!will!know!that!their!best!option!to!move! around!the!city!is!to!use!the!tram!number!3.!Or!if!it!is!known!that!a!part!of!the! sidewalk!is!obstructed!for!any!reason,!an!alternative!travelling!path!could!be! adopted.!!!! In!this!thesis!the!focus!is!on!providing!a!set!of!tools!for!collection!of!data! from! the! mobility/impaired! people’s! travelling! experience,! and! for! geo/ localization! of! the! images! provided! by! the! citizen! about! the! problems! in! the! city.!In!other!words,!this!thesis!work!aims!at!collecting!the!travelling!history!of! people!with!mobility!impairment!in!the!city!when!they!find!their!own!ways,!in! order! to! detect! the! accessible! path! for! this! group! of! people,! and! enrich! the! information! about! the! paths! for! them! by! providing! the! exact! location! of! pictures!taken!from!the!problems.!!
1.1 Thesis!goal!and!main!contribution!
The!work!done!in!this!thesis!aims!to:! • Design!and!develop!an!Android!application!for!data!collection!from!the! available!sensors!and!camera!in!smartphones!and!tablets.! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 1!Integrated!Circuit! 2!Microelectromechanical!Systems! 3!Inertial!Measurement!Units! 4!Secure!Digital!memory!card! 2!Microelectromechanical!Systems!Introduction 15
!
• Develop!an!experimental!3D!geographical!map,!
• And!then,!using!the!above!3D!map!to!geo/localize!a!given!picture!taken! from!the!real!world.!!
These! three! phases! of! the! work! can! be! introduced! as! a! complementary! work! to! MEP! (Maps! for! Easy! Paths)! project,! supported! by! Polisocial! (a! program! of! social! responsibility! and! commitment! of! Politecnico! di! Milano).! MEP!project!is!going!to!develop!a!set!of!innovative!tools!and!solutions!for!the! enrichment! of! geographical! maps! with! information! about! the! accessibility! of! urban!pedestrian!paths!for!people!with!mobility!problems.!!
Within!the!MEP!project,!the!tools!designed!in!this!thesis!can!support!the! collection! of! data! from! built/in! sensors! and! pictures! taken! with! defined! frequency! by! the! cameras! that! can! be! used! further! to! detect! the! accessible! paths.!!
In!this!work,!we!show!how!the!embedded!camera,!GPS!and!other!sensors! (e.g.!accelerometer,!gyroscope,!magnetometer,!and!barometer)!in!the!common! smartphones!and!tablets,!can!be!employed!to!collect!data!over!a!path!that!has! been! travelled! by! a! pedestrian! (specifically! those! with! motor! impairment),! and! how! a! 3D! geographic! map! is! created! to! make! the! geo/localization! of! a! given!image!more!accurate.!!
1.1 Structure!of!the!thesis!
The!structure!of!the!thesis!is!as!the!following:!!
• In!Chapter!2,!an!overview!of!the!thesis!is!given!by!introducing!the!MEP! project,! which! this! thesis! is! a! contribution! to.! The! goals! of! the! MEP! project!are!presented,!the!main!scenario!is!described,!the!target!users! of! the! project! are! defined! and! categorized! and! finally! the! considerations! regarding! the! structure! to! be! developed! are! given! based!on!which!the!different!phases!of!the!project!are!decided.!!
• !Chapter!3!explains!the!development!of!a!mobile!application,!aiming!at! collecting!implicit!data!by!gathering!IMU!data!and!images!from!user’s! travelling!experience!to!be!used!in!the!MEP!project.!
• In! Chapter! 4,! a! 3D! map! is! constructed! based! on! a! common! 2D! map! (Google!Map)!after!giving!an!overview!of!the!related!works!carried!out! so!far.!!The!map!construction!requirements!are!given!and!the!map!is! designed!and!realized.!!
16 Chapter 1. Introduction
• In!Chapter!5!the!3D!map!developed!in!the!previous!chapter!is!used!to! increase! the! accuracy! of! geo/localization! of! images! that! are! taken! by! users.!Similar!works!are!presented,!requirements!of!the!procedure!are! explained! and! then! geo/localization! of! images! is! designed,! implemented!and!experimented.!
• In! Chapter! 6! the! conclusion! of! the! current! thesis! are! presented! and! suggestions!on!possible!future!works!are!given.!
• In! Appendix! A,! the! mobile! application! described! in! Chapter! 3! is! represented.!!
• In!Appendix!B,!the!table!of!specification!of!the!3D!modeling!computer! programs!is!presented.!!
!
Chapter!2 !
Overview!
2.1 The!MEP!project!
“Maps! for! Easy! Paths”,! or! MEP,! is! a! Polisocial! project! (a! program! of! social! responsibility! of! Politecnico! di! Milano)! that! aims! to! develop! an! automated! system! to! enrich! a! public! map! with! information! about! accessibility! of! city! routes!(roads,!sidewalks,!walkways,!etc.)!through!the!active!contribution!and! participation!of!the!target!users!which!includes!people!with!motor!disabilities! (primary!contribution)!and!active!citizenship!(secondary!contribution).!
The! primary! contribution! is! the! collection! of! data! obtained! implicitly,! through! specific! tools! (e.g.! smartphones! or! dedicated! electronic! systems),! which!are!able!to!automatically!detect!the!location!(via!GPS)!and!possibly!the! characteristics!of!the!ground!condition!(e.g.!the!presence!of!holes,!slopes,!etc.).! All!citizens!can!also!contribute!by!uploading!information!about!the!problems! and! barriers! through! their! smartphones! /! tablet! /! pc,! as! the! secondary! contribution.!!
Given!in!Figure!2.1,!!the!scenario!could!be!described!in!the!following!way:!! I. The! MEP! android! application! installed! on! the! wheelchair! users’! smartphone! or! tablet! will! track! the! routes! that! the! user! is! choosing! through!the!city.!These!routes!can!be!counted!as!accessible!for!people! with!mobility!difficulties.!!To!track!the!user,!the!application!sends!GPS,! data! of! sensors,! and! optionally! the! pictures! taken! by! the! camera!will! be!sent!to!the!server,!which!uses!fusion!techniques!to!reconstruct!the!
18 Chapter 2. Overview
route.!The!collection!of!such!data!is!“implicit”!since!it!doesn’t!require! any!intervention!by!the!user.!!
II. On!the!other!side,!there!are!the!active!citizens!who!take!pictures!of!the! problems! and! barriers! they! face! in! the! city.! These! pictures! together! with! sensor! information! will! be! uploaded! to! the! server;! this! part! of! application!is!collaborative!and!is!referred!as!“explicit”!data!collection,! since!it!requires!the!contribution!of!the!user.! III. Server!receives!the!“implicit”!and!“explicit”!data!(see!Section!2.2!and! 2.3)!and!goes!for!construction!or!updating!a!3D!geographical!map,!and! in!the!meanwhile!records!the!accessible!routes!and!its!corresponding! information!by!processing!the!implicit!data!received!from!wheelchair! users.!Now!having!these!sorts!of!data,!server!can!respond!to!the!final! users.!!
IV. The! project! goal! is! to! respond! to! the! needs! of! people! with! motor! impairments! in! finding! the! accessible! paths! through! the! city.! These! final!users!are!ranging!from!users!with!manual!or!electric!wheelchair,! the!elderly!with/without!mechanical!support,!to!people!in!temporary! situations!of!reduced!mobility,!including!injured!and!people!with!small! children,! to! be! able! to! move! freely! in! the! urban! context! without! the! limitations! of! architectural! barriers.! These! people! can! ask! the! server! about! the! best! route! they! can! choose! to! reach! their! destination! by!
! Figure!2.1!MEP!project!scenario!
Overview 19
!
using! the! application.! Now! server! can! suggest! an! accessible! route! based!on!the!collected!data.!
V. Not! only! the! people! with! motor! impairment,! but! also! the! public! entities! and! associations,! which! are! interested! to! know! about! the! possible! problems! that! people! with! motor! impairment! are! dealing! with! on! their! way! around! the! city! are! of! the! final! users! of! the! data! collected!by!the!MEP!server.!Knowing!these!problems!can!help!them!to! make! best! decisions! about! changes! in! urban! design! and! solving! architectural! problems! in! the! city.! Knowing! the! accessible! routes! for! people! with! motor! impairments! can! also! be! helpful! for! relevant! organizations! to! find! out! “how”! to! improve! the! quality! of! the! city! context.!!
2.2 Collection!of!implicit!data!
The!MEP!project!aims!to!help!people!with!motor!impairments!to!travel!freely! around!the!city.!!In!this!case,!the!project!is!looking!for!an!Android!application,! which!suggests!the!user!the!best!accessible!way!to!her/his!destination!in!the! city,!based!on!the!data,!which!is!the!result!of!processes!done!by!the!server!on! what!has!been!collected!by!the!application.!The!data!will!be!collected!in!two! different!ways:!implicit!and!explicit.!Here,!the!implicit!data!and!how!they!are! collected! and! used! is! discussed.! Then! in! section! 2.3! the! explicit! data! will! be! described.!As!shown!in!the!Figure!2.2,!the!implicit!data!is!collected!by!some!of!our! target!users!with!motor!impairments.!At!this!moment,!for!precision!of!data,!it! is! assumed! that! these! people! are! wheelchair! users! since! the! smartphone! or! tablet!can!be!fixed!on!their!wheelchair.!A!fixed!smartphone!(or!tablet)!on!the! wheelchair!can!collect!more!accurate!data!than!the!condition!that!it!is!held!in! hand.!Given!this!assumption,!the!scenario!is!as!following:!!
• When! a! wheelchair! user! travels! in! the! city,! the! MEP! application! installed! on! his/her! smartphone! (or! tablet)! saves! the! GPS! and! IMU3! information!on!the!SD/card4!of!the!device.!These!data!will!be!stored!in! text!format!(*.txt).!Such!these!data!is!called!implicit,!since!it!is!collected! while!the!user!has!no!intervention.!
• When!the!data!is!collected,!the!user!can!upload!them!on!the!server!for! further! processes.! The! techniques! embedded! in! the! server,! use! a!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
3!Inertial!Measurement!Units! 4!Secure!Digital!memory!card!
20 Chapter 2. Overview
fusion! of! collected! data! to! find! the! paths! and! the! ground! conditions! that!the!user!has!experienced!during!his/her!travel!around!the!city.!! • Knowing! the! path! and! condition! of! ground,! the! server! can! decide!
about! the! level! of! accessibility! of! that! particular! path.! At! this! point,! when!the!target!users,!who!are!those!people!with!motor!impairments,! send!a!request!to!the!server!about!the!best!accessible!route!that!they! can! choose! to! reach! their! destination! through! the! MEP! application,! based! on! the! collected! data,! the! server! responds! to! their! request! by! suggesting!the!best!accessible!path.!!
Therefore,! the! implicit! data,! collected! by! some! of! the! target! users,! will! lead!to!knowing!the!accessible!paths!alternatives.!So!the!server!needs!at!least! one!user!to!experience!a!specific!path!to!be!able!to!respond!to!the!other!users! requests!over!a!route,!which!can!be!covered!by!that!particular!path.!But!what! if! there! is! no! implicit! data! about! a! path! to! the! destination?! If! the! server! just! relies!on!these!implicit!data!it!will!be!incapable!of!responding!in!majority!of! cases.!Thus,!another!sort!of!data!is!needed!to!empower!the!server.!This!sort!of! data!will!be!discussed!in!the!following!section.!!
! Figure!2.2!Collection!of!implicit!data!
Overview 21 !
2.3 Matching!of!explicit!data!
As!discussed!before,!the!server!uses!the!collected!data!to!decide!about!the!best! accessible!path!for!a!person!with!motor!impairments.!Relying!on!implicit!data,! which!is!based!on!some!of!the!target!users’!experience,!is!not!enough!to!satisfy! the! needs! of! the! application! users.! ! The! server! should! be! able! to! decide! and! choose!between!possible!paths!when!it!has!not!enough!collected!history!about! them.!!To!solve!this!problem,!the!MEP!project!uses!an!initial!3D!geographic!map! that!has!some!information!about!the!condition!of!the!paths.!This!map!should! be! dynamically! updated! according! to! the! new! changes! on! the! paths.! In! this! case,!it!needs!a!new!sort!of!data,!that!are!called!here!as!“explicit!data”.!These! data! are! collected! by! some! active! users! who! report! the! problems! and! obstacles! they! face,! on! their! way! around! the! city.! But! what! is! the! initial! 3D! map!and!how!it!will!be!constructed?!What!are!the!explicit!data!and!how!they! will!be!used!for!our!purpose?!!
As! it! is! shown! in! Figure! 2.3! another! Android! application! is! introduced,! which! is! responsible! for! collecting! the! needed! data! for! construction! of! a! 3D! map.!This!application!is!called!“MEP/data!logger”!or!“MEP/DL”,!and!is!shown! in!green!color.!!This!application!will!be!used!only!for!experimental!purposes,! and!those!who!are!collecting!data!using!this!application,!are!volunteers!who! are! helping! the! project! to! move! ahead.! Again,! it! is! assumed! that! these! volunteers! are! wheelchair! users! since! the! smartphone! or! tablet! can! be! fixed! on!their!wheelchair!for!collection!of!more!accurate!data.!!
On! the! other! side,! there! are! some! active! citizens! who! are! interested! to! report! the! problems! and! obstacles! on! the! city! paths! through! our! former! Android!application!(MEP).!They!take!a!picture!from!the!scene!and!upload!it! to!the!server.!Together!with!this!picture,!some!more!details!about!the!location! and!orientation!of!the!device!during!which!it!was!taking!picture!will!be!sent!to! the! server.! Now,! the! server! can! compare! and! match! that! single! image! with! some!pictures!taken!from!the!3D!map!to!find!the!exact!location!of!the!image! and!update!the!3D!map!according!to!that.!The!scenario!can!be!summarized!in! the!following!way:!!
• A! volunteer! wheelchair! user! having! MEP/DL! Android! application! on! his/her!smartphone!or!tablet!goes!through!the!city!routes!and!collects! pictures! taken! periodically! (e.g.,! every! 2! seconds).! At! the! same! time! the! application! records! all! the! needed! sensor! and! GPS! data! simultaneously.!!
22 Chapter 2. Overview
• The! collected! data! by! the! MEP/DL! will! be! stored! on! the! device’s! SD/ card.!!
• The! data! recorded! on! the! SD/card! will! be! uploaded! to! the! server! for! further!processes.!
• The! algorithms! embedded! in! the! server! use! the! collected! data! to! construct!a!3D!map!based!on!a!given!2D!map.!!
• On!the!other!side,!some!active!citizens!report!the!problems!in!the!city! by! taking! pictures! from! that! problem! or! obstacles! through! the! MEP! application!and!upload!that!single!image!together!with!its!data!to!the! server.!! • The!server,!that!is!equipped!with!a!3D!map,!receives!the!data!sent!by! active!citizens.!Knowing!the!GPS!information!of!the!image!it!can!take! some!pictures!from!the!3D!world!around!that!location.!By!comparing! the!taken!picture!from!the!3D!map,!it!can!match!the!single!image!to!the! 3D!map!and!find!the!exact!location!of!that!subject.!! • Therefore!the!server!is!able!to!detect!the!exact!geographical!location!of! the!image,!knowing!its!location!in!the!3D!map.! ! Figure!2.3!Matching!of!explicit!data!
Overview 23
!
2.4 The!issues!and!needs!of!the!MEP!project!
The! MEP! project’s! main! issues! are! how! to! employ! smartphones! and! similar! devices! to! collect! the! best! possible! data! (implicit! and! explicit)! with! enough! accuracy,!and!then!how!these!collected!data!can!be!utilized!to!build!a!3D!map! and! improve! the! accuracy! of! the! position! of! the! pictures! taken! by! the! active! citizens.!In!this!regard,!the!project!needs!to!investigate!the!new!possibilities!in! the! new! generation! of! smartphones! and! tablets.! The! hardware! and! software! advances! have! changed! the! technology! domain.! Newly,! smartphones! and! tablets!have!become!of!the!most!powerful!devices!equipped!with!a!wealth!of! electrical!chips!performing!most!of!the!functions!previously!found!only!in!full/ fledged!desktop!operating!systems.!Fast!growth!of!technology!requires!more! investigation!into!new!“possibilities”.!These!new!possibilities!can!help!us!find! more!optimal!solutions!for!the!problems.!
To! guarantee! that! the! solution! is! optimal,! all! the! possibilities! should! be! checked!and!evaluated.!It!is!not!practical!to!just!use!all!capabilities!of!a!device! at!the!same!time.!The!busier!the!hardware!is,!the!more!the!performance!slows! down.!So!doing!a!trade!off!between!device!performance!and!reaching!the!goals! of!the!project!is!necessary.!!
Moreover,! as! explained! earlier,! the! MEP! project! aims! also! to! use! smartphones!and!tablets!to!construct!the!initial!3D!geographic!map.!To!do!so,! frequent!images!should!be!taken!from!a!route!together!with!other!positional! and!orientation!information,!and!be!stored!in!device!memory.!The!format!os! these! data! should! be! compatible! with! the! further! algorithms,! which! are! constructing!the!3D!map!and!doing!matching!process.!!
In! addition,! since! the! MEP! project! is! under! development,! and! the! development!is!being!done!in!parallel,!there!is!no!access!to!the!final!result!of! the!3D!map.!So!to!adapt!the!matching!algorithms!to!the!input!data!taken!from! smartphones! and! tablets,! a! testing! 3D! area! that! is! constructed! based! on! pictures! taken! from! the! real! world! is! needed.! In! that! regard,! it! would! be! possible! to! find! the! best! match! between! the! 3D! world! and! a! single! picture! taken!by!smartphones!or!tablets.!!!!
Knowing!the!issues!of!MEP!project!the!needs!are!described!as!following:!! • All! the! capabilities! of! the! new! smartphones! (and! tablets)! should! be!
accessible!and!examined,!and!the!accuracy!of!the!collected!data!should! be!tested.!Therefore,!a!direct!access!to!sensors!and!GPS!data!is!needed.! These!data!should!be!collected!simultaneously!in!a!given!interval.!! • To!do!the!examination,!it!is!necessary!to!be!able!to!change!the!device!
24 Chapter 2. Overview access!to!sensors!and!GPS!is!not!limited!to!just!retrieving!data,!but!the! access!should!include!the!possibility!of!parameters!modification.! • The!possibility!of!taking!informative!pictures!from!smartphones!(and! tablets)!should!be!identified. ! • Since!the!project!is!also!interested!in!using!smartphones!and!tablets!to! collect! data! for! the! construction! of! a! 3D! map,! there! should! be! the! possibility!of!frequent!image!capturing!and!frequent!data!recording.!! • To! simply! read! and! import! the! data! collected! by! smartphones! and!
tablets!into!further!works,!all!information!should!be!saved!in!a!written! format,!preferably!in!a!text!file.!!
• All! the! mentioned! data! and! images! should! be! exportable,! and! the! syntax!and!format!of!the!outputs!should!be!compatible!with!standards! that!will!be!used!by!the!algorithms!for!construction!of!the!3D!map.!! • For!experimental!purposes,!an!area!of!a!city!should!be!simulated!in!a!
3D!form!based!on!pictures!taken!from!that!area!in!the!real!world.!! • In! the! simulated! 3D! area,! there! should! be! a! possibility! of! setting! the!
viewpoint! latitude,! longitude! and! altitude.! With! these! conditions,! finding!the!best/matched!view!to!a!single!image!will!be!possible.!
2.5 Thesis!work!phases!
This! thesis! will! assist! the! MEP! project! to! overcome! the! points! mentioned! above.!!The!work!can!be!divided!into!three!phases:!
! First!Phase:!Application!development!for!implicit!data!collection! Aims!to!develop!an!Android!application!for!experimental!purposes!to! detect! the! hardware! capabilities! and! testing! the! performance! of! smartphones!and!tablets.!(MEP/data!logger)!
! Second!Phase:!Simulation!of!a!geographic!3D!area!!
Aims! to! prepare! an! experimental! 3D! model! compatible! with! mobile! output!data.!!! ! Third!Phase:!Finding!the!best!match!between!a!picture!and!the!3D! model! Tries!to!find!the!way!to!explore!in!the!simulated!3D!area!and!find!the! best!viewpoint,!which!is!matched!to!a!single!given!image!knowing!the! position!and!orientation!information.!!! Each!of!these!three!phases!will!be!described!in!depth!in!the!next!chapters.!
!
Chapter!3 !
MEPNDL:!an!Application!for!the!Collection!of!
Implicit!Data!!
3.1 Introduction!
As! discussed! in! Chapter! 1,! the! MEP! project! aims! to! help! people! with! motor! impairment! to! travel! easier! around! the! city! by! showing! them! an! accessible! path!to!their!desired!destination.!The!accessible!paths!can!be!interpreted!from! a! history! of! data! collected! dynamically! by! some! of! the! users! with! motor! impairments!when!they!go!around!the!city,!and!the!information!reported!by! the! active! citizens! about! the! problems! in! the! city.! To! this! end,! MEP! project! intends!to!employ!smartphones!and!tablets!with!Android!operating!system,!to! collect!its!essential!data.!Using!two!Android!applications,!one!for!experimental! purposes! (MEP/Data! Logger! application)! and! another! one! for! general! uses! (MEP!application),!the!data!needed!for!MEP!project!will!be!collected!through! the!smartphones!or!tablets.!Then!by!processing!these!data,!the!MEP!server!is! able!to!decide!about!the!level!of!accessibilities!of!the!paths,!and!can!suggest!its! target!users!the!most!accessible!path!to!a!destination.!
As! it! was! explained! earlier! in! Chapter! 2,! this! thesis! is! a! complementary! work! to! the! MEP! project,! and! can! be! divided! into! three! phases! (see! Section! 2.5).! In! this! chapter! we! will! discuss! the! first! phase! of! the! thesis,! “the! application! for! implicit! data! collection”.! In! the! following! sections! the! background! knowledge! for! such! an! application! will! be! discussed,! the! design! and! implementation! phases! and! system! architecture! of! MEP/DL! application!
26 Chapter 3. MEP-DL
will! be! described,! and! at! the! end! of! this! chapter! the! application! will! be! evaluated!and!the!results!will!be!discussed.!!
3.2 Related!works!
Several! collaborative! projects! aim! to! improve! city! accessibility,! through! the! Web! or,! more! recently,! through! smartphones/tablets! applications.! Here! is! reported! the! main! approaches! proposed! for! the! tracking! of! users! through! sensors!data!of!mobile!devices,!either!general/purpose!or!specifically!aiming! at!building!accessibility!maps.!!
3.2.1 IBM!research!groupNBrazil!
The! project! [1]! aims! at! using! a! crowdsourcing! platform! that! enables! the! collaborative!creation!of!accessibility!maps.!Using!smartphones!and!tablets!to! provide! the! ability! of! “sensing”! the! surrounding! environment,! the! project! introduces!the!crowdsourcing/based!data!collection!that!can!be!done!based!on! collaboration! of! the! users.! The! final! output! is! an! augmented! version! of! the! contents! that! are! provided! in! common! 2D! maps! (e.g.,! Google! Map,! OpenStreetMap,! etc.)! with! the! purpose! of! providing! more! realistic! insight! to! accessibility! challenges! that! may! be! found! in! the! city.! The! main! goal! in! this! project!is!to!enrich!the!map!with!dynamic!updates!with!more!precise!details.!
To!this!end,![1]!introduces!two!mobile!applications,!“Citizen!Sensing”![2]! and! “Breadcrumb”,! to! collect! the! needed! data! for! its! analysis.! The! Citizen! Sensing!is!an!application!based!on!direct!interaction!of!the!user,!which!allows! him/her!to!report!an!urban!event!and!its!details!in!a!text!or!audio!format.!The! other! application,! Breadcrumb,! provides! a! tool! that! captures! periodically! a! sequence! of! measurements! based! on! device’s! geo/location! (longitude! and! latitude),! acceleration,! orientation,! and! ID! number,! without! any! need! to! the! user! intervention.! It! is! assumed! that! a! path! taken! mostly! by! people! with! disabilities!can!be!perceived!as!a!friendlier!route.!!
The!main!issue!that![1]!is!dealing!with!is!the!precision!of!data!collected! by!the!Breadcrumb!application.!GPS!sensors!in!mobile!devices!have!errors!in! capturing!the!geographical!coordinates.!This!fact!causes!noises!on!the!samples! collected.! In! this! case,! [1]! tries! to! enhance! the! quality! of! data! by! “simple! moving! average”! of! 10! previous! estimates! of! the! velocity! of! the! device,! knowing!the!time!that!device!has!been!in!point!A!and!the!time!that!it!is!in!the! next!point!B.!!
In!spite!of!the!fact!that!this!project!has!many!features!in!common!with!the! MEP!project!in!different!aspects,!the!fundamental!difference!is!in!the!approach!
3.2. Related works 27 ! taken!to!increase!the!precision!of!data.!!IBM!research!project!tries!to!improve! the!precision!by!estimating!a!new!data!(velocity)!based!on!existing!data!which! are!very!dependent!on!the!number!of!users,!whereas!in!the!MEP!project,!the! MEP/DL!application!collects!several!types!of!sensors!data!and!also!the!route! images!for!a!better!estimation!of!the!location!and!for!improving!the!precision! of!data.!!
3.2.2 Funf!Journal!
Funf! Journal! [3]! is! an! android! application! that! is! built! to! use! “Funf! open! Sensing! Framework”,! which! is! an! extensible! sensing! and! data! processing! framework!for!mobile!devices.!This!application!intends!to!collect!information! related! to! mobile! devices! that! can! be! used! afterwards! by! users! who! may! be! researchers,! self/trackers,! or! anyone! interested! in! such! data.! ! Allowing! the! user! to! configure! data! collection! parameters,! including! all! common! phone! sensors,!collecting!data!automatically,!and!using!SD/Card!for!storing!the!data! are! of! the! features! that! can! also! be! found! in! the! MEP/DL! application.! This! application! also! provides! secure! encrypted! data! storage,! possibility! of! exploring!data!through!the!app,!and!an!amount!of!in/app!options!for!exporting! the!data!using!Bluetooth!or!Wi/Fi!connections.!!
In!fact,!Funf!Journal!is!a!general/purpose!application!with!specified!data! format! storage.! It! is! just! designed! to! help! individuals! to! collect! their! desired! information! through! the! smartphones! and! tablets! and! let! them! use! the! data! for!any!purpose.!Excluding!the!possibility!of!Image!capturing!from!MEP/DL!we! can! claim! that! these! two! applications,! Funf! Journal! and! MEP/DL,! are! going! after! a! same! goal,! which! is! automatic! and! simultaneous! data! collection! from! smartphones!and!tablets.!Due!to!the!requirements!of!MEP!project,!the!MEP/DL! application! also! provides! simultaneous! image! capturing! in! parallel! to! the! sensor! data! collection.! Moreover,! Funf! Journal! records! the! data! in! the! encrypted! format.! So! to! retrieve! the! original! data! there! is! a! need! to! decrypt! back!the!data!through!the!application!itself.!In!this!case,!the!taken!data!from! direct!access!to!the!memory!would!not!be!useful,!while!the!MEP!project!needs! to! have! also! the! option! of! retrieving! data! directly! from! the! memory! (SD! memory! card).! That! is! because! the! size! of! sensor! data! files! (containing! long! period!data!collection)!may!get!too!large!and!the!images!are!inherently!large! files,! so! sometimes! the! better! option! to! transfer! data! may! be! using! wired! connection!not!just!using!Wi/Fi!or!Bluetooth!connection.!!!!
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3.2.3 Accessibility!maps!
Large! groups! of! people! in! the! world! encounter! difficulties! in! taking! part! in! everyday!life!due!to!their!functional!limitations.!To!aid!this!group!of!people!in! overcoming!their!problems!and!encouraging!them!to!be!more!active!in!society,! several! projects! and! applications! have! been! proposed! providing! navigating! solutions.!Wheelmap!and!MapAbility!are!two!pioneer!systems!which!provide! navigating!systems!considering!the!needs!of!different!group!of!people,!as!will! be!described!in!the!following!paragraphs.!!
Wheelmap![4]!is!an!open!and!free!online!map!that!is!designed!to!search,! find!and!mark!wheelchair!accessible!places,!discussing!the!“Open!Accessibility! data”! concept.! Open! accessibility! data! is! the! data! related! to! the! accessibility! issues!and!associated!with!geographical!data,!which!could!benefit!people!with! disabilities! or! special! needs.! The! collection! of! data! is! based! on! collaborative! involvement! of! users! sharing! the! information! and! marking! the! level! of! wheelchair!accessibility!of!places.!!This!project,!as!well!as!MEP!project,!aims!to! empower! mobility/impaired! people! to! participate! in! society! easier,! more! actively!and!more!efficiently,!and!raising!the!awareness!about!the!issues!these! people!are!dealing!with!and!help!the!government!for!agenda!settings.!!
Although! this! project! is! now! providing! mobile! applications! for! Android! operating! system! and! iOS,! it! is! not! using! the! capacity! of! these! devices! to! improve! the! quality! of! information! collected! by! the! users.! The! MEP! project! carrying! the! same! goal,! is! trying! to! improve! the! precision! of! data! collected! with!or!without!intervention!of!the!user,!to!construct!a!powerful!framework,! which!is!able!to!fulfill!a!vast!rage!of!people!with!mobile!impairment!needs.!!
An! example! of! similar! project! with! some! added! features! is! the! “MapAbility”! project! [5].! This! project! aims! at! collecting! urban! accessibility! information!involving!the!users!themselves!who!report!physical!barriers!and! facilities!within!the!city.!The!information!such!as!location!of!the!appropriate! services,!roads,!parking!lots!and!restaurants,!presence!of!obstacles,!and!width! of!sidewalks!can!be!added!to!the!map!by!the!users,!and!these!information!can! the!other!users!to!check!the!accessibility!of!a!city!before!visiting!and!planning! their!route.!!!
3.3 Background!knowledge!!
This!section!tries!to!clarify!some!of!the!terms!and!definitions!that!will!be!used! in!the!following!sections.!!3.3. Background knowledge 29 !
3.3.1
Smartphone!sensors!! The!sensors!are!built/in!chips,!which!can!be!found!in!almost!every!new!device! in!the!market,!as!in!smartphones!and!tablets.!These!sensors!can!measure!the! position!and!orientation!of!the!device,!and!can!be!used!in!several!applications! for! different! purposes.! Some! of! the! common! sensors,! which! are! usually! present!in!smartphones!and!are!being!used!in!this!project,!are!listed!below.!!• GPS! (global! positioning! system)! is! a! built/in! chip! inside! some! smartphones,!which!is!typically!used!to!determine!the!location,!speed,! direction,! and! time! of! the! device! by! retrieving! the! information! from! the!satellites. This!technology!is!ran!by!the!US!Military.!The!accurate! location! estimation! has! made! this! technology! being! widely! used.! However,! the! huge! battery! consumption! and! slow! response! are! the! negative!aspects!of!this!technology.!!
• Accelerometer! is! a! sensor! that! is! designed! to! measure! the! acceleration! (g/force5),! which! is! typically! present! in! smartphones.! When! the! device! goes! from! a! standstill! to! any! velocity,! the! accelerometer! responses! to! the! vibrations! associated! with! such! movement.! In! this! regard,! it! is! able! to! detect! the! orientation! and! position!of!the!device!and!the!rotation!of!its!screen.!Figure!3.1!shows! the!axes!of!movement!on!the!smartphones.!
• Magnetometer! is! a! built/in! compass! that! can! be! usually! found! in! smartphones.! It! measures! the! magnetic! field! in! the! Micro! Tesla6! unit! and!can!detect!the!north!and!south!of!the!earth.!This!sensor!is!crucial! for! detecting! the! relative! orientation! of! the! device! relative! to! the! Earth's!magnetic!north.!To!correct!the!raw!magnetic!measurements,!it! often!incorporates!the!other!sensors,!such!as!accelerometer.!!!
• Gyroscope!is!a!tool!to!detect!the!orientation!of!the!smartphone.!This! built/in! chip! can! measure! Roll,! Pitch! and! Yaw7! of! the! device! automatically! (see! Figure! 3.1).! The! difference! between! the! accelerometer! and! gyroscope! in! estimation! of! the! orientation! of! the! device! is! that! the! gyroscope! measures! the! changes! in! orientation! based! on! changes! in! rotational! velocity! while! the! accelerometer! can! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
5!Gravitational!force,!a!measurement!of!the!type!of!acceleration!that!indirectly!causes!
weight.!
6!!The!unit!of!magnetism.!
7! ! The! rotation! axes! that! are! originally! used! as! aircraft! axis.! Yaw! or! vertical! axis! is!
perpendicular!to!the!wings!of!aircraft,!Pitch!or!lateral!axis!passes!through!one!wingtip! to!the!other!wingtip,!and!Roll!or!longitudinal!axis!passes!through!the!plane!from!nose! to!tail.!!
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measure! the! orientation! in! the! up/down! plane! considering! gravity! acceleration8.!!
• Barometer! is! a! tool! to! measure! the! atmospheric! pressure,! which! is! traditionally!used!to!predict!short/term!changes!in!weather9.!!Some!of! new!generation!of!smartphones!and!tablets!are!now!equipped!with!the! barometer! chip,! but! not! just! for! weather! prediction,! but! to! measure! the! altitude10! of! the! device! (knowing! the! current! pressure! at! sea! level)! and! better! navigation.! ! The! GPS! cannot! measure! the! altitude! accurately! and! its! response! is! very! poor! in! cloudy! weather.! The! barometer!aids!the!GPS!to!calculate!the!altitude!more!accurately!and! incorporating!the!other!sensors,!so!it!cooperates!also!in!the!navigation.!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
8!Via!Einstein’s!equivalency!principle!
9! High! air! pressure! means! a! warm! and! sunny! day,! and! low! air! pressure! means! bad!
weather,!high!wind,!rain!or!snow.!Consequently,!if!the!air!pressure!rises,!it!means!the! weather!is!getting!warmer,!and!if!it!drops,!it!means!that!the!weather!is!getting!colder,! windier!or!wetter.!!
10! Here! altitude! means! the! distance! between! the! device! and! the! WGS! 84! reference!
ellipsoid!(the!latest!version!of!the!World!Geodetic!System).!It!is!presented!in!meter.!!
! Figure!3.1!The!Accelerometer!axes!and!the!Gyroscope!rotation!parameters!
3.4. MEP-DL requirements 31
!
3.4 MEPNDL!requirements!
MEP! project! aims! to! develop! an! experimental! Android! application! for! smartphones! and! tablets! to! study! the! possibilities! of! data! collection! through! these! devices.! The! data! collected! by! this! application! will! be! also! used! to! construct! a! dynamically! updatable! 3D! map,! which! empowers! the! server! to! decide!about!the!accessibility!level!of!the!paths.!Knowing!the!goals!and!needs! of! project,! it! is! possible! to! specify! the! requirements! of! MEP/DL! application! development.! These! requirements! can! be! split! up! into! the! following! two! categories:!!
Functional*requirements:*
a. Getting!access!to!the!hardware!of!the!mobile!device! b. Capturing!images!periodically!using!back!camera!
c. Displaying!the!preview!of!the!back!camera!view!to!the!user!
d. Force! the! device! to! be! awake! (not! to! go! to! sleep)! while! capturing! images! e. Recording!all!possible!sensors!measurements!simultaneously! f. Doing!the!previous!requirement!in!the!background!! g. Notifying!the!user!about!the!background!activities!of!the!application! h. Providing!the!possibility!of!turning!back!to!the!app!after!clicking!on!its! notification! i. Letting!the!user!configure!her/his!data!collection!parameters! j. Saving!the!last!changes!in!configuration!for!the!subsequent!run!of!the! app! k. Checking!if!the!GPS!is!on!or!not!(this!information!is!critical)!! l. Storing!data!with!a!specified!format!in!memory! m. Specifying!the!logical!file!management!in!the!memory! Nonfunctional*requirements:**
a. Performance:! the! required! resources,! response! time,! and! battery! consumption!of!the!application!in!different!devices.!
b. Scalability:! the! requirements! regarding! the! ability! of! handling! the! growing!amount!of!data!in!a!proper!manner.!
c. Availability:!the!requirements!to!reach!a!degree!to!which!the!system! is! operable! at! the! start! of! the! mission! at! any! time! by! the! authorized! user.!!
d. Security:! requirements! for! protection! of! the! system! from! malicious! penetrations!and!actions!to!protect!data!when!system!is!broken!down.!!
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e. Data! integrity:! the! requirements! to! guarantee! that! the! data! is! correctly!collected!and!is!protected!to!be!modified!from!outside!of!the! application.!
In! the! design! and! implementation! process,! steps! are! taken! in! order! to! meet!the!above!requirements.!!
3.5 MEPNDL!design!
In!this!section,!the!design!phase!of!the!MEP/DL!application!will!be!explained.! In!particular,!it!consists!of!two!different!phases,!the!design!of!the!structure!of! the! application! and! the! interface! of! the! application.! In! the! structural! design! section,! the! general! structure! and! functionalities! of! the! application! will! be! designed,! and! in! the! interface! design! section,! the! general! look! and! arrangement!of!the!contents!will!be!sketched.!!
3.5.1 MEPNDL!structural!design!!
MEP/Data! Logger! (or! MEP/DL)! is! an! Android! application! for! experimental! purposes.! It! is! developed! in! Java! programming! language! and! is! compatible! with! Android! 4.0! and! higher! versions.! This! application! can! get! access! to! the! common!hardware!embedded!in!the!smartphones!and!tablets!new!generation,! and!can!collect!their!data!simultaneously.!These!data!will!be!stored!in!the!SD! memory! card! of! the! device! and! will! be! used! for! further! works.! Figure! 3.2! shows!the!structure!outline!of!the!MEP/DL!application.!!
As! discussed! before! in! Chapter! 2,! the! MEP! project! will! provide! two! applications:!MEP/App!and!MEP/DL.!But!there!are!some!common!features!in! ! Figure!3.2!MEP/DL!application!structure!outline!
3.5. MEP-DL design 33
!
these! two! applications.! The! features! of! these! two! applications! are! shown! in! Table!3.1.!! ! Table!3.1!MEP!and!MEP/DL!Features!Comparison! ! MEP/App! MEP/DL!! Com m on !Fe at ur es
! 1. Getting! access! to! the! sensors! data! and! recording! them!
simultaneously!!
2. Saving! information! in! a! particular! format! on! the! SD! memory!card!
3. Doing! the! above! processes! as! a! background! service! (not! interrupting!the!foreground!applications)!and!notifying!the! user!about!background!activities.! Ex tr a! Fe at ur es ! 4. Easy/to/use!user! interface! 5. Real!time!connection!to! the!server.! 6. Single!photo!capturing! 7. Importing!map!and!other! related!data!from!the! server.! 4. Multiple!photo!capturing! (periodically)!while! displaying!camera!preview! 5. Forcing!the!device!to!stay! awake!while!taking!pictures! 6. Saving!photos!on!the!SD! memory!card!in!a!particular! format.! 7. User!control!on!data! collection!parameters! 8. Saving!the!last!configuration! in!the!memory!for!the!next! uses!
As! seen! in! Table! 3.1,! some! parts! of! MEP/DL! application! can! be! used! in! MEP/App.! In! this! case,! we! can! also! call! the! MEP/DL! application! the! experimental!version!of!the!target!application!(MEP)!and!some!modifications! to!the!MEP/DL!will!lead!to!the!final!MEP!application.!!
Here,! the! features! of! the! MEP/DL! application,! which! are! fulfilling! the! requirements!mentioned!before,!are!described.!!
• Hardware!access!and!sensor!recording:!
The!goal!of!the!development!of!MEP/DL!is!the!collection!of!data!using! the! built/in! sensors! in! smartphones! and! tablets.! Getting! the! permission! to! access! the! device! sensors,! MEP/DL! should! be! able! to!
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collect! initial! raw! motion! and! position! data.! In! order! to! collect! such! data,! GPS,! accelerometer,! magnetometer,! gyroscope! and! barometer! should! be! accessed! through! the! application.! These! sensors! are! described!in!more!details!in!Section!3.3.1.!!
Moreover,! such! data! should! be! recorded! simultaneously! and! be! synchronized! with! each! other,! since! discrete! and! individual! information! causes! huge! error! in! estimations.! To! guarantee! that! the! precision! of! data,! the! sensors! information! should! be! stored! simultaneously!in!such!a!way!that!those!which!are!correspondents!are! easily!searchable!through!the!timestamp.!!
• Saving!data!and!images!on!the!memory:!
The! data! should! be! stored! in! the! device! for! further! uses.! The! saving! process! should! be! fast,! file/exportable! and! secure! in! terms! of! being! harmless!to!the!other!applications!and!the!device!operating!system.!All! the! devices! compatible! with! the! Android! operating! system! support! a! shared!external!storage!that!can!be!used!by!the!installed!applications.! Unlike! the! internal! memory! that! is! a! private! storage! space,! the! external!memory!is!public,!readable,!modifiable!and!retrievable.!This! external! memory! can! be! removable,! such! as! SD/Cards,! or! non/ removable.! The! issues! with! this! type! of! memory! are! in! providing! confidentiality!and!integrity!of!the!data,!since!the!data!can!be!accessed,! modified! or! deleted! freely! from! anywhere.! In! order! to! prevent! unauthorized! data! modification! and! utilization! the! files! should! be! stored! in! the! memory! under! a! random! path,! which! is! difficult! to! be! retrieved!from!outside!the!application.!!
After! saving! the! data,! they! should! be! retrieved! and! used! for! further! tasks/computations.! In! this! case,! they! should! be! stored! in! a! format!compatible!with!the!algorithms!that!will!be!used.!!Therefore!we! will!store!the!sensors!data!in!a!simple!text!file!format!(.txt)!to!let!them! be!easily!imported!by!any!algorithm.!The!images!should!also!be!stored! in! simple! JPEG! files! (.jpg)! for! their! high! compatibility.! The! memory! management!is!also!an!issue!since!the!files!should!be!searchable,!and! the! organization! of! files! should! be! logical.! Their! aspects! will! be! discussed!in!Section!3.6.2.10.!!
• Storing! sensor! data! in! background! and! notifying! about! the! background!activities:!
The!most!critical!and!basic!information!is!the!sensors!data.!These!data! can! also! be! collected! while! the! user! is! using! other! applications! on!
3.5. MEP-DL design 35
!
her/his! device.! This! would! increase! the! usability! of! the! application.! But!if!there!are!some!activities!in!the!background,!the!user!should!be! aware!of!them!and!be!able!to!stop!them!for!sometime.!Otherwise!the! app!will!violate!security!issues,!and!the!device!may!run!out!of!storage! space!because!after!a!long!period!the!background!activity!will!store!a! lot!of!data!in!the!memory.!!So!if!there!is!a!background!activity!the!user! should!be!notified!and!by!pressing!the!notification!s/he!should!be!able! to!go!back!to!the!app!and!stop!the!application!if!it!is!needed.!! • Displaying!the!camera!preview!and!capturing!images!frequently:! The!GPS!sensors!in!mobile!devices!usually!have!errors!in!capturing!the! position!data.!To!accurate!the!positioning!and!track!the!user!precisely,! the!MEP!project!aims!at!using!images!taken!frequently!while!the!user! is! moving.! To! this! end,! the! MEP/DL! has! to! provide! the! possibility! of! capturing! multiple! images! from! the! front! of! the! user! in! a! defined! frequency!while!the!user!is!also!able!to!see!a!preview!of!the!capturing! scene!to!make!sure!if!the!camera!is!looking!at!a!right!direction.!!
• Force!the!device!to!be!awake!while!capturing!images:!
If! the! device! goes! asleep! the! camera! will! unexpectedly! stop! working.! This!issue!would!be!annoying!to!the!user!and!would!cause!unpleasant! gaps! in! the! collected! data.! In! order! to! resolve! this! issue,! the! device! should!stay!awake!while!the!application!is!working.!! • User!control!on!data!collection!parameters:! To!provide!better!control!on!the!type!of!data,!which!are!required!to!be! collected!with!respect!to!the!experiment!needs,!the!application!should! give!the!user!the!possibility!to!configure!the!parameters!of!the!desired! data!collection.!!
• Saving! the! last! data! collection! configuration! for! the! next! time! uses:!
It! would! be! more! pleasant! to! keep! the! last! configurations! instead! of! setting! it! every! time.! So,! the! application! should! save! the! information! about!the!last!configuration!somewhere!in!the!memory!and!retrieve!it! as!soon!the!application!starts!again.!!
3.5.2 Interface!design!
Considering! the! limitations! and! possibilities! in! designing! the! mobile! application!interface,!and!due!to!the!standards!and!user/habits,!!the!!outline!!of!
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Figure! 3.3! The! outline! of! the! MEP/DL! interface:! (a)! first! page! of! the! application! which! appears!as!soon!as!the!application!triggers;!(b)!second!page!which!follows!the!first!one:! (b)(upper)!second!page!with!the!setting!panel!hidden!and!(b)(lower)!second!page!with! the! panel! appearing;! (c)! the! detailed! interface! of! the! setting! panel! already! shown! in! (b)(lower);! (d)! notification! tab! showing! a! background! process:! (d)(left)! the! display! of! the! notification! in! the! notification! bar,! (d)(right)! ! display! of! notifications! in! the! notification!drawer.!!
(a)$Star(ng$Page$
(b)$Second$Page$
(d)$No(fica(on$of$the$background$process$ (c)$Se9ng$Panel$
3.6. MEP-DL Application Development 37
!
the! interface! of! designed! application! in! Section! 3.5.1! is! shown! in! Figure! 3.3.! The!application!is!assumed!to!have!two!pages:!the!starting!page!contains!just! the! logo! (see! Figure! 3.3.a),! and! the! second! one! provides! all! the! application! functions! (see! Figure! 3.3.b).! The! second! page! is! divided! into! four! fixed! sections!(camera!display,!buttons,!in/app!notification,!and!information!button)! and! contains! a! setting! panel.! The! setting! panel! (see! Figure! 3.3.c)! is! also! divided! into! three! sections! for! camera,! location! and! sensor! related! options,! and! a! confirmation! button.! The! background! processes! push! a! notification! in! the!notification!bar,!which!is!visible!as!shown!in!Figure!3.3(d).!!!
3.6 MEPNDL!Application!Development!!
The!MEP/DL!application!has!been!developed!in!“Android!Studio”!version!1.0.2,! on! MacBook! Pro! with! OS! X! version! 10.9.5! operating! system,! using! Java! programming!language.!The!Overview!of!the!developed!application!is!shown! in!Figure!3.4.!!!
As! discussed! earlier! in! Section! 3.4,! the! application! is! designed! to! get! access! to! and! control! the! sensors! to! collect! data,! the! camera! to! capture! frequent!pictures,!and!the!external!memory!to!store!all!the!data!in!a!specific! format.! To! access! them,! due! to! the! rules! of! android! framework,! access! permission!should!be!requested!to!the!user!during!installation.!Moreover,!the! data! collection! should! be! configurable! and! there! should! be! a! possibility! to! trigger!a!process!in!background!while!it!is!visible!and!controllable!through!its! notification.! In! addition,! a! proper! user! interface! is! essential! to! build! an! adequate! level! of! interaction! between! the! application! and! the! user.! In! the! following,! the! device! requirements! for! such! implementation! and! the! details! about!how!to!implement!the!above!factors!are!briefly!presented.!
3.6.1 Device!requirements!
The!minimum!API!level!of!the!Android!platform!on!which!the!application!runs! is!14!and!it!is!designed!to!run!on!the!target!API!level!of!21.!The!back!camera,! external! storage,! GPS,! accelerometer,! gyroscope,! and! magnetometer! are! the! required!hardwares!for!the!device!and!barometer!is!the!preferred!sensor!that! can!enhance!the!accuracy!of!the!final!collected!data.!The!compatibility!of!the! application!has!been!tested!on!mobile!devices!of!Nexus!4,!Nexus!5,!Nexus!7,! Moto!X,!LG!G2,!Galaxy!S4!mini,!and!Lenovo!Yoga!tablet!2!for!collection!of!data! and! the! satisfying! result! has! been! verified.! The! specifications! of! the! mobiles! devices!mentioned!are!represented!in!Table!3.2.!
38 Chapter 3. MEP-DL ! Mo b ile 'D ev ic e' O. S.' ve rs io n ' CPU ' Me m or y' Ba ck 'c am er a'r es ol u tio n ' (M P 1 /p ixel s) ' Sen so rs 'avai lab le ' RAM '(G B )' SD Dca rd '(G B )' Ne xu s&4 & 4. 3/ 4. 4/ 5. 0& Qu alc om m & sn ap dra go n&S 4& Pr o/ &1. 5& G H z& 2& & 16& & 8/ 3264& ×2448 & GP S,&Ac c2 ,&G yr o 3 ,&P rx4 /A m b 5 ,& Com 6 ,&B ar7 ,&M ic P 8 ,&& Ne xu s&5 & 5. 0& Qu alc om m & sn ap dra go n&8 00 /& 2. 26& G H z& 2& 32 & 8/ 3264 ×2448 & GP S,&Gy ro ,&Ac c,&C om ,&P rx ,& Pr es s9 ,&H all10 & Mo to &X & 5. 0& Qu alc om m & sn ap dra go n&8 01 /& 2. 5&GH z 2& 16 & 13/ 4128 ×3096 & Ac c,&C om ,&Gy r0, &lig ht ,&Pr x& LG &G 2& 4. 4/ 5. 0& Qu alc om m & sn ap dra go n&8 00 /& 2. 26& G H z& 2& 16 & 13/ 4160 ×3120 & GP S,&Ac c,&Gy ro ,&P rx, &C om & Ga la xy &S 4&m in i& 4. 3/ 4. 4/ 5. 0& Qu alc om m & sn ap dra go n&4 00 /& 1. 7& G H z& 1. 5& 8& 8/ 3264 ×2448 & GP S,&Ac c,&Gy ro ,&P rx, &C om & Le novo& Yoga& Ta bl et &2 & 4. 4& In te l&A to m &Z 37 45 & 2& 16 & 8/ 3264 ×2448 & Ac c,&C om ,&Am b,& H all ,&V ib 11 ,& 1V & Me ga &Pi xe l,& 2V &Ac ce le ro m et er ,&3 V&Gy ro sc op e,&4V &Pr ox im ity ,&5V &Am bie nt &lig ht ,& 6V & Com pas s,& 7V &Ba ro m et er ,& 8V &Mi cr op ho ne ,&9V &Pr es sur e,&10 V &Ha ll&E ffe ct, &11 V &Vi br at io n& & & Ta ble !3 .2 !Sp ec ific at io ns !o f!t he !M ob ile!d ev ic es !o n!w hic h!M EP /DL !co m pa tib ilit y!i s!t es te d!
