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Integrating openstreetmap data and sentinel-2 Imagery for classifying and monitoring informal settlements

Abstract

The identification and monitoring of informal settlements in urban areas is an important step in developing and implementing pro-poor urban policies. Understanding when, where and who lives inside informal settlements is critical to efforts to improve their resilience. This study aims at integrating OSM data and sentinel-2 imagery for classifying and monitoring the growth of informal settlements methods to map informal areas in Kampala (Uganda) and Dar es Salaam (Tanzania) and to monitor their growth in Kampala. Three building feature characteristics of size, shape and Distance to nearest Neighbour were derived and used to cluster and classify informal areas using Hotspot Cluster analysis and ML approach on OSM buildings data. The resultant informal regions in Kampala were used with Sentinel-2 image tiles to investigate the spatiotemporal changes in informal areas using Convolutional Neural Networks (CNNs). Results from Optimized Hot Spot Analysis and Random Forest Classification show that Informal regions can be mapped based on building outline characteristics. An accuracy of 90.3% was achieved when an optimally trained CNN was executed on a test set of 2019 satellite image tiles. Predictions of informality from new datasets for the years 2016 and 2017 provided promising results on combining different open source geospatial datasets to identify, classify and monitor informal settlements.

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Integrating openstreetmap data and sentinel-2 Imagery for classifying and monitoring informal settlements

Author: Ayo, Brenda
Year: 2020
Source: https://run.unl.pt/bitstream/10362/93641/1/TGEO0221.pdf
INTEGRATING OPENSTREETMAP DATA AND SENTINEL-
2
IMAGERY FOR CLASSIFYING AND MONITORING
INFORMAL SETTLEMENTS
B enda Ayo
ii
INTEGRATING OPENSTREETMAP DATA AND
SENTINEL-2 IMAGERY FOR CLASSIFYING AND
MONITORING INFORMAL SETTLEMENTS
Disse a ion supe ised by
Joel Dinis Bap is a Fe ei a da Sil a, PhD
Ins i u o Supe io de Es a ís ica e Ges ão de In o mação,
Uni e sidade No a de Lisboa
Lisbon, Po ugal
Disse a ion co-supe ised by
P o . D . Hanna Meye ,
Ins i u e o Landscape Ecology,
Heisenbe gs . 2, D-48149 Müns e
Disse a ion co-supe ised by
Ignacio Gue e o
Ins i u e o New Imaging Technologies,
Uni e si a Jaume I
Cas ellón de la Plana, Spain
Feb ua y 2020
iii
DECLARATION OF ORIGINALITY
I decla e ha he wo k desc ibed in his documen is my own and no om someone
else. All he assis ance I ha e ecei ed om o he people is duly acknowledged and all
he sou ces (published o no published) a e e e enced.
This wo k has no been p e iously e alua ed o submi ed o NOVA In o ma ion
Managemen School o elsewhe e.
Lisbon, Po ugal, Janua y 2020
B enda Ayo
i
ACKNOWLEDGMENTS
P incipally, I would like o hank my Supe iso s, Joel Dinis Bap is a Fe ei a da Sil a
(PhD), P o . D . Hanna Meye and Ignacio Gue e o. You we e ins umen al om he
incep ion, h ough he execu ion and end o his Thesis. I am ex emely g a e ul and
hono ed o ha e collabo a ed wi h you.
I am ex emely g a e ul o all he p o esso s ha helped h ough his mas e ’s p og am
especially p o esso s Ma co Painho and Ch is oph B ox o hei guidance and suppo
h oughou he p og am du a ion.
Thank you o my coho and ellow MSc. GeoTech g adua e s uden s – especially
Damien and Chamodi - you ha e been inc edible esou ces, whose posi i e and
ha dwo king spi i has made my Mas e ’s expe ience so much mo e enjoyable and un.
Las ly, hanks o my iends and amily who we e o g ea suppo e en i you we e
housands o miles away.
In eg a ing Opens ee map Da a and Sen inel-2 Image y o
Classi ying and Moni o ing In o mal Se lemen s
ABSTRACT
The iden i ica ion and moni o ing o in o mal se lemen s in u ban a eas is an impo an
s ep in de eloping and implemen ing p o-poo u ban policies. Unde s anding when,
whe e and who li es inside in o mal se lemen s is c i ical o e o s o imp o e hei
esilience. This s udy aims a in eg a ing OSM da a and sen inel-2 image y o
classi ying and moni o ing he g ow h o in o mal se lemen s me hods o map in o mal
a eas in Kampala (Uganda) and Da es Salaam (Tanzania) and o moni o hei g ow h
in Kampala. Th ee building ea u e cha ac e is ics o size, shape and Dis ance o nea es
Neighbou we e de i ed and used o clus e and classi y in o mal a eas using Ho spo
Clus e analysis and ML app oach on OSM buildings da a. The esul an in o mal
egions in Kampala we e used wi h Sen inel-2 image iles o in es iga e he spa io-
empo al changes in in o mal a eas using Con olu ional Neu al Ne wo ks (CNNs).
Resul s om Op imized Ho Spo Analysis and Random Fo es Classi ica ion show ha
In o mal egions can be mapped based on building ou line cha ac e is ics. An accu acy
o 90.3% was achie ed when an op imally ained CNN was execu ed on a es se o
2019 sa elli e image iles. P edic ions o in o mali y om new da ase s o he yea s
2016 and 2017 p o ided p omising esul s on combining di e en open sou ce
geospa ial da ase s o iden i y, classi y and moni o in o mal se lemen s.

i
KEYWORDS
In o mal Se lemen s;
Remo e Sensing;
U baniza ion;
Machine Lea ning (ML);
Random Fo es (RF);
Con olu ional Neu al Ne wo ks (CNN);
OpenS ee Map (OSM)
Sen inel-2 sa elli e image y
ii
ACRONYMS
CNN - Con olu ional Neu al Ne wo ks (CNNs)
DEM - Digi al ele a ion model
DSM - Digi al su ace model
EO – Ea h Obse a ion
GEOBIA - Geog aphic objec -based image analysis
GPS - Global posi ioning sys em
GSO - Global slum on ology
HR - High Resolu ion Sa elli e Image y
ISDA - In o mal se lemen da abase a las
ISUP - In o mal se lemen upg ading P og amme
KOTAKU - Ko a Tanpa Kumuh
LiDAR - Ligh de ec ion and anging
MGD - Millennium de elopmen goals
MKL - Mul iple Ke nel Lea ning
MLTs - Machine Lea ning Techniques
OBIA - Objec -based image analysis
OHSA - Op imized Ho spo Analysis
OOA - Objec -o ien ed analysis
OSM – Open S ee Map
PSUP - Pa icipa o y slum upg ading P og amme
RF - Random o es
RGB – Red G een Blue
SDI - Shack/Slum Dwelle s In e na ional
SVM - Suppo Vec o Machine
UAV - Unmanned Ae ial Vehicle
iii
UN – Uni ed Na ions
UN-Habi a – Uni ed Na ions Human Se lemen s P og amme
VGG - Visual Geome y G oup
VHR - Ve y high esolu ion
VHR – Ve y High Resolu ion Sa elli e Image y
WDI - Wo ld De elopmen Indica o s
ix
INDEX OF THE TEXT
DECLARATION OF ORIGINALITY .................................................................. iii
ACKNOWLEDGMENTS ....................................................................................... i
ABSTRACT ..............................................................................................................
KEYWORDS ........................................................................................................... i
ACRONYMS ......................................................................................................... ii
INDEX OF THE TEXT .......................................................................................... ix
INDEX OF TABLES ............................................................................................... xi
INDEX OF FIGURES ........................................................................................... xii
1. INTRODUCTION .......................................................................................... 1
1.1. Backg ound and Mo i a ion........................................................................... 1
1.2. Resea ch Gap Iden i ica ion ........................................................................... 3
1.3. Resea ch Aim ................................................................................................ 4
1.4. Me hodology o e iew .................................................................................. 5
1.5. Thesis S uc u e ............................................................................................. 5
2. LITERATURE REVIEW ............................................................................... 6
2.1. Cha ac e is ics o In o mal Se lemen s .......................................................... 6
2.1.1. Building cha ac e is ics: ......................................................................... 6
2.1.2. Access Cha ac e is ics: ........................................................................... 7
2.1.3. Loca ion and neighbou hood Cha ac e is ics: ......................................... 7
2.2. OpenS ee Map o U ban Analy ics .............................................................. 7
2.3. App oaches o iden i ying and Mapping In o mal Se lemen s ...................... 8
2.3.1. Su ey and census-based app oach ......................................................... 8
2.3.2. Pa icipa o y-based app oach.................................................................. 9
2.3.3. GIS and Remo e sensing-based app oach ............................................... 9
2.4. Ho Spo Clus e ing Analysis ....................................................................... 11
2.5. An o e iew o Machine Lea ning Techniques ............................................ 11
2.5.1. Con olu ional neu al-ne wo ks.............................................................. 13
3. DATA AND CASE STUDY .......................................................................... 16
3.1. Case S udy .................................................................................................. 16
3.2. Da ase s and P e-P ocessing ........................................................................ 18
3.2.1. OSM Da a ............................................................................................. 18
3.2.2. Sa elli e Image y ................................................................................... 19
3.2.3. Re e ence da a....................................................................................... 20
4. RESEARCH METHODOLOGY ................................................................. 21
4.1. Da a En ichmen and Compu a ion o Pa ame e s ........................................ 21
4
polygons, and a he same ime iden i y in o mal egions ac oss he en i e ci y and no jus
pa icula places. The e is also need o examine whe he simila building polygons in in o mal
se lemen s - simila in he sense o geome ical p ope ies exhibi a spa ial pa e n. The in o mal
se lemen buildings cha ac e is ics coupled wi h Machine lea ning algo i hms could help o p edic
whe e in o mal se lemen s could be and also i hese cha ac e is ics a e exhibi ed in a ying
geog aphical loca ions. This will help educe he agg a a ion ha comes up du ing hei
de ec ion o in en o y o planning issues and also p o ide mo e insigh and unde s anding
on he g ow h o hese se lemen s.
The o he challenge wi h mapping in o mal se lemen s a ci y, egional o coun y le el is he
absence o adequa e da a o analysis a hese scales. The a ailabili y o open sou ce sa elli e
image y like Landsa and Sen inel da a p o ide a wide co e age bu he spa ial esolu ions
hey o e does no p o ide o adequa e dis inguishing be ween o mal and in o mal
se lemen s in ci ies. Howe e , wi h accu a e delinea ing o hese se lemen s a a ine scale,
hese sa elli e images can be used o moni o he g ow h o in o mali y o e ime since he
in eg a ion
o spa io- empo al analysis o in o mal se lemen s is s ill inadequa e.
1.3. Resea ch Aim
The main aim o his esea ch wo k is o in eg a e OSM da a and sen inel-2 image y o
classi ying and moni o ing he g ow h o in o mal se lemen s.
To achie e he main esea ch Aim, he ollowing sub ques ions a e add essed:
1. How can we exploi he po en ial o using buildings ou line cha ac e is ics such as size
and shape o di e en ia e In o mal se lemen s om Fo mal Se lemen s?
2. Is i possible o p edic in o mal a eas in a ci y by unde s anding housing in o mali y in
o he ci ies o simila con ex using buildings ou line cha ac e is ics and machine
lea ning?
3. Wha is he mos app op ia e Machine Lea ning echnique based on accu acy o p edic
in o mal a eas in a ci y based on buildings ou line cha ac e is ics?
4. How can we exploi he po en ial o eely a ailable Sen inel-2 sa elli e image y wi h
ad anced machine lea ning o es ima e he g ow h o In o mal se lemen s?

5
1.4. Me hodology o e iew
Based on he esea ch ques ions, he ollowing me hodology wo k low was adap ed:
 P ep ocessing o OSM da a and Sa elli e Image y. This in ol ed da a cleaning and
p epa a ion sui able o Analysis.
 OSM Building polygons en ichmen wi h Fea u e geome ic and opologic
cha ac e is ics.
 Ho spo clus e ing analysis on building ea u es aining da ase o clus e In o mal
se lemen buildings om he o mal ones.
 Tes and selec he bes classi ie based on accu acy o p edic in o mal a eas in a ci y
based on simila i y con ex o buildings ou line cha ac e is ics.
 Sen inel-2 image classi ica ion. This s age in ol es slicing he images in o iles and
using he p edic ed In o mal se lemen egions om he s ep abo e o gene a e aining
se on image iles o co esponding da e pe iod. The ea e , a Con olu ional Neu al
Ne wo ks Model is ained o iden i y Image iles ha belong o In o mal se lemen s.
The ained model is hen used o p edic In o mal se lemen image iles o o he
empo al da ase s.
1.5. Thesis S uc u e
The esea ch is o ganized as ollows:
 Chap e 2 e iews he ela ed wo ks and heo e ical backg ound on in o mal
se lemen s, app oaches o mapping and iden i ying in o mal se lemen s, and Machine
Lea ning Algo i hms
 Chap e 3 desc ibes he s udy a ea, da ase s and ools used o he esea ch.
 Chap e 4 desc ibes he implemen a ion de ails o he me hodology and he expe imen s
conduc ed
 Chap e 5 p esen s he esul s;
 Chap e 6 add esses he analysis and discussion o he esul s including he limi a ions
o he esea ch;
 Chap e 7 p esen s a summa y o he conclusions by answe ing he main e-sea ch
ques ions and ecommenda ions o u u e wo ks.
6
2. LITERATURE REVIEW
This chap e gi es an o e iew on he undamen al concep s ela ed o his esea ch and he
cu en s a e o esea ch in he ield o mapping in o mal se lemen s I highligh s he physical
cha ac e is ics o in o mal se lemen s, a discussion on a ious app oaches used o map
in o mal se lemen s and he in eg a ion o GIS and in o mal se lemen s and Machine Lea ning
Algo i hms.
2.1. Cha ac e is ics o In o mal Se lemen s
The challenge wi h mapping and iden i y wha an in o mal se lemen is s a s wi h he absence
o a s anda d de ini ion which has esul ed in o ailu e o inco po a e hese se lemen s in o
census and demog aphic su eys a na ional o e en dis ic le el [23]. Based on li e a u e, hey
ake on names like Slum, In o mal, Squa e , Spon aneous, Ghe o, Illegal, I egula , o
desc ibed by local names such as Fa ela, bidon ille (F ench), mudun-sa i (A abic), bai os da
la a (Po uguese) ownship o gecekondu (Tu kish), o men ion bu a ew [24]. The UN-Habi a
quali a i ely de ined a slum as a household ha is lacking ei he o imp o ed wa e , imp o ed
sani a ion, enu e secu i y o o e c owded li ing en i onmen is based on a measu e o
dep i a ion indica o s. On he o he hand, he de ini ion o in o mal se lemen s diffe s om
slum as hose a eas ha de eloped h ough unau ho ized occupa ion o land ou side a legal,
egula o y, planned and p o essional amewo k o example [26, 27]. The e o e, quan i ying
and classi ying in o mal se lemen s/ slums in a uni e sally accep able way is pa icula ly
di icul because (a) Wha is e e ed o as a slum in one coun y may be a good quali y o
li ing and (b) o e ime and a se lemen can ge o malized h ough slum upg ading p og ams
[27]. Howe e , o e he yea s, some ea u es ha e been unique o in o mal se lemen s which
include:
2.1.1. Building cha ac e is ics:
Buildings in in o mal se lemen s end o be smalle (10 o 40 m2), ha e simple shapes ha a e
mos ly ec angula and he e ogeneous o ien a ion compa ed o hose in o mal se lemen s. The
building densi y in slums is usually high since he spacing and gap be ween buildings in almos
nonexis ence [29, 30].
7
2.1.2. Access Cha ac e is ics:
Slums gene ally ha e i egula oad access ne wo k wi h oads ha a y in ype, su ace and
wid h. [30]The oads a e always sho in leng h wi h many dead ends and dangles. The oads
and access ne wo k in In o mal se lemen s a e usually na ow wi h limi ed usage by mo o
ehicles because hey a e ei he wo na ow o le a ca pass o can only allow access o on
ehicle a a ime. Slums a e cha ac e ized wi h mos ly oo pa hs.
2.1.3. Loca ion and neighbou hood Cha ac e is ics:
Slums a e usually loca ed in haza dous a eas like nea dumping si es, we lands, along ailways,
sewe age canals. [31]This is because mos o he land whe e hese ea u es a e loca ed is public
land and in abandoned. They a e usually close o employmen oppo uni ies o unskilled and
low skilled jobs like manu ac u ing indus ies o ease access o employmen .
2.2. OpenS ee Map o U ban Analy ics
Access o spa ial da a has changed apidly o e he yea s om adi ionally p ohibi i e sou ces
o openly licensed con en and da a due o changes in In o ma ion Technology and
Communica ion (ITC) b ough abou by in e ne , social media and inexpensi e po able GNSS
de ices like mobile phones and Handheld GPS [10, 32]. OSM is he mos popula geospa ial
open da a sou ce pla o m con aining billions o en ies o VGI and is main ained by a massi e
communi y o mappe s om a ound he wo ld all wo king o-wa ds he goal o cu a ing
accu a e and comple e geospa ial da a. In he ecen yea s, he e has been an inc eased use o
VGI da a no only in GIScience bu also in o he ields like ecology, planning, compu e science
e c. [33,34,35]. o academic esea ch and s udies. OSM oads laye s a e associa ed wi h he
highes comple eness compa ed o buildings based on a ecen s udy [36] ha es ima es ha
he OSM oads ha e eached mo e han 80% o comple eness a a global scale. OSM da ase s
ha e been used o ex ac u ban in o ma ion and o analysis [37, 38]. These da ase s a e usually
used as a supplemen a y sou ce o in o ma ion o land-use mapping wi h emphasis on
classi ying a i icial su aces [39], by combining OSM and sa elli e images o ex ac
in o ma ion ela ed o he u ban en i onmen [39–42]. Few esea ch s udies exis on building
oo p in s da a en ichmen o u ban analysis [43, 44]. In hese s udies, au oma ic me hods a e
de eloped by using he geome ic and opological ea u es in oo p in da a, in o de o enhance
he maps wi h he building usage in o ma ion. Henn e al. [45] de i ed he a chi ec u al ypes
8
o buildings based on 3D coa se block models wi h e ical walls and la oo s using Suppo
Vec o Machines (SVMs), whe eby, geome ic ea u es such as leng h, wid h, a ea, and
deg ee o pe pendicula i y o building oo p in s, ypes o buildings, as well as heigh
in o ma ion o buildings a e equi ed o he classi ica ion p ocess.
2.3. App oaches o iden i ying and Mapping In o mal Se lemen s
S udies on he de elopmen and exis ence o in o mal se lemen s ha e been ca ied ou no
only by geog aphe s bu also social scien is s who pu emphasis on social and economic aspec s
o in o mal se lemen s. Due o hei complexi y and e e a ying na u e, in o mal se lemen s
a e usually inadequa ely ep esen ed on u ban and ci y maps which lea es hem ulne able o
neglec by conce ned go e nmen agencies. The e a e b oadly h ee me hods used o collec
da a o in o m cha ac e iza ion and classi ica ion o in o mal se lemen s: household su eys
and census, Pa icipa o y app oaches and Ea h Obse a ion image y analysis using geospa ial
Techniques [46].
2.3.1. Su ey and census-based app oach
These app oaches use da a collec ed h ough census and su eys like da a on demog aphics,
popula ion, social and economic aspec s o map dep i a ion and po e y. This da a maybe
coupled wi h da a om o icial si es like he wo ld Bank is used o map slums based on social,
economic and habi a /In as uc u e a iables. In [47], an explo a o y ac o analysis o de ine
he Slum Se e i y Index (SSI) Mexico Ci y based on measu ing he shel e dep i a ion le els
o households om 1990 o 2010. The esul s showed ha he SSI dec eased signi ican ly
be ween 1990 and 2000 as a esul o se e al policy e o ms bu inc eased be ween 2000 and
2010. Weeks e al. [48] quan i a i ely used census da a o Acc a, Ghana o c ea e a slum index
based on he UN slum indica o s o measu e he concen a ion o slums. High co ela ions we e
ound be ween he slum index, he socio-economic cha ac e is ics o neighbo hoods and ce ain
land co e me ics de i ed om VHR sa elli e image y. A usion o open sou ces physical and
socio-economic da a in [9] was used o de elop an indica o da abase o cha ac e izing slum
se lemen s by le e aging da a mining echniques o mapping slums in Kenya’s majo ci ies.
I ’s impo an o no e ha one o he majo challenges is ela ed o census unde -co e age due
o ime cons ain , inadequa e quali y assu ance and inaccu a e add esses. The absence o
9
censuses in in o mal se lemen s is la gely due o he inaccessibili y o make-shi s uc u es
due o poli ical in ole ance o gene al diso de [30].
2.3.2. Pa icipa o y-based app oach
The pa icipa o y app oaches in ol e he coope a ion and pa icipa ion o he in o mal
se lemen dwelle s in o de o gene a e bo h spa ial and non-spa ial in o ma ion o p o ile
in o mal se lemen s [30]. The pa icipa o y slum upg ading P og amme (PSUP), es ablished
by he UN-Habi a and he Slum Dwelle s In e na ional (SDI) was a pa icipa o y app oach
ha encou aged and empowe ed communi ies o become ac i e pa ne s wi h s akeholde s in
de ising s a egies o plan sus ainable in o mal se lemen upg ades [49]. The Ko a Tanpa
Kumuh (KOTAKU) pla o m and p og am is esponsible o he handling o in o mali y in
Indonesia h ough inc easing he ole o local go e nmen and communi y pa icipa ion.
In o mali y is de ined by buildings, local s ee s, d inking wa e supply, communi y d ainage,
was ewa e managemen , ga bage managemen , and i e p o ec ion [50]. Howe e ,
Pa icipa o y-based app oaches a e ex emely ime consuming and e o -in ensi e is
cha ac e ized by limi ed spa ial co e age making i di icul o co e la ge a eas like egional
o dis ic le els [30].
2.3.3. GIS and Remo e sensing-based app oach
The connec ion be ween in o mal se lemen s and geog aphy has been a ocus o s udy o a
long ime. Many esea ch s udies ha e in es iga ed he alue o using Image- based
iden i ica ion o in o mal se lemen s h ough emo e sensing and o he GIS analysis ools o
mo e han 2 decades [23,13,48,49, 50]. Th ee key c i e ia a e o en used in such s udies: small
g ain size, high g ound co e age and i egula access ne wo ks. O he ac o s such as p oximi y
o haza dous a eas, lack o ege a ion and low- quali y oo ing a e some imes included. Such
s udies o en con la e in o mali y wi h slums. Bu while mos such s udies map a bina y
dis inc ion be ween o mal and in o mal mo phologies, some adop a mo e nuanced app oach.
B adley e al [54] deploy he use o bo h HR and VHR sa elli e image y o map in o mal
se lemen s in de eloping coun ies using machine lea ning. They used he Canonical
Co ela ion Fo es s (CCFs) o lea n he spec al signal o in o mal se lemen s om HR sa elli e
image y. The second me hod used a CNN combined wi h VHR sa elli e image y o ex ac
ine g ained ea u es. Pe e and Gulnaz s udied he use o objec based change de ec ion and
objec acking o in o mal se lemen s using emo ely sensing da a in Cape own (Sou h

10
A ica) be ween he pe iod 2000 o 2015. The objec change de ec ion p o ided o de ec ion
o hema ic changes pe objec and o documen he changes o hei p ope y alues and
po en ial mo emen . In [52], he au ho s discuss and e alua e a ious machine lea ning
app oaches and a combina ion o a ious ea u es o de ec slums. The classi ica ions me hods
e alua ed included mul i-class and hie a chical o dis inguish u ban om o he classes such as
ege a ion and wa e . [55] p esen ed he use o CNNs o he de ec ion o in o mal se lemen s
om VHR i.e. 0.60m Quickbi d sa elli e image o he ci y o Da es Salaam, Tanzania acqui ed
in 2007 and compa ed he esul s wi h s a e o he a classi ie s ha use handc a ed ea u es.
[56] e alua ed and poin ed ou ha Objec Based Change De ec ion (OBCD) and OBIA a e he
mos p omising echniques o au oma ized iden i ica ion o new buildings in in o mal
se lemen s, bu hey need o wo k wi h VHR da a ec i ied wi h a DSM o he same o
compa ible spa ial esolu ion. [57] This pape aimed o documen and unde s and basic
in as uc u al condi ions and hei changes o e an eigh -yea pe iod o he Kibe a Slum using
VHR sa elli e images by analyzing he dynamics o physical ans o ma ions o building sizes
and heigh s, buil -up densi ies, and building a angemen s. A pionee ing s udy by Ho man
[58] used OBIA o iden i y in o mal se lemen s om IKONOS image y in he Ci y o Cape
Town. In o mal se lemen classi ica ion was unde aken using sub-classes ha desc ibed
se lemen o ms (dense, medium, new and b igh ) based on complex hie a chy and class
desc ip ions such as ex u al and spec al ea u es. The au ho ound ha he abili y o de ec
in o mal se lemen s was dependen on he spa ial esolu ion o he image y. No quan i a i e
esul s we e p esen ed as he indings o he s udy. This esea ch was la e imp o ed by
Ho mann e al. [59], who showed ha se e al modi ica ions we e equi ed when applying
ex ac ion me hods o a Quickbi d scene in B azil. The adap ions included simpli ied and
p uned class-hie a chies o make he chosen class desc ip o s in heo y mo e ans e able o
compa able scenes. The esul s o his s udy demons a ed ha he selec ion o a s a egy o
in o mal se lemen segmen a ion and classi ica ion is da a and con ex -speci ic. Shekha [60]
delinea ed in o mal se lemen s in Pune Ci y, India, using Quickbi d image y. The s udy
highligh ed he e icacy o he de eloped me hodology o disc imina e in o mal egions by
desc ibing ypical cha ac e is ics o hese se lemen s. Fuzzy membe ship unc ion o ex u e,
geome y, and con ex ual in o ma ion we e used o achie e an o e all accu acy o mo e han
87%. Kohli e al. [30] expanded upon he wo k o Ho mann e al. [59] and de eloped Gene ic
Slum On ology (GSO), which can be used as pa o a concep ual classi ica ion OBIA schema.
11
Howe e , echniques like OBIA equi e VHR Da a usually wi h a esolu ion o unde 5 me e s
o de ec slum objec s and is a e y ime consuming app oach and equi es an adop ion o
pa ame e s and alues o a AOI. This makes hem di icul o ans e o o he ci ies o
coun ies. I should be no ed ha mos o he ecen app oaches o iden i y and map in o mal
se lemen s in ol e he usion o wo o mo e app oaches.
2.4. Ho Spo Clus e ing Analysis
Ho spo analysis is a spa ial analysis and mapping echnique in e es ed in he iden i ica ion o
clus e ing o spa ial phenomena in o s a is ically signi ican ho spo s and cold spo s [61].These
spa ial phenomena a e depic ed as poin s in a map and e e o loca ions o e en s o objec s.
A ho spo is an a ea ha has highe concen a ion o e en s compa ed o he expec ed numbe
gi en a andom dis ibu ion o e en s [62]. Ho spo de ec ion has e ol ed om he s udy o
poin dis ibu ions o spa ial a angemen s o poin s in a space [63] o unde s and spa ial
pa e ns in ime. The applica ion o ho spo analysis wi hin public heal h, epidemiological
esea ch and c ime mapping and esea ch has inc eased signi ican ly in he pas couple o
decades mainly due o ad ancemen in GIS-based so wa e. Ho spo analysis usually in ol es
he inciden coun o poin s in a loca ion, A ibu es ha u he desc ibes poin s o Pe iod o
ime i.e. Da e o ime o e en s. Ve y ew s udies a e based on he use o ho spo analysis in
he mapping o In o mal se lemen s because i equi es mos ly ec o da a which is qui e
insu icien o slums compa ed o as e da a. Mohamed e . al in oduced a me hod o
iden i ying and p edic ing in o mal se lemen s using s ee in e sec ions da a using Ge is-O d
Gi Ho Spo Analysis and a machine lea ning app oach[20].
2.5. An o e iew o Machine Lea ning Techniques
Machine lea ning echniques (MLTs) (Figu e 2) gene a e knowledge in a lea ning phase by
means o aining da a and ans e his o new da a o p edic ion and gene aliza ion e en wi h
noise-con amina ed and incomple e da a [58,59].
MLTs ha e been success ully used in analyzing and modeling a ious complex en i onmen al
disciplines, including in medicine, inancial ma ke s, ecology, geog aphy, biomedicine, and
epidemiology [66–69]. The g owing popula i y o MLTs can be a ibu ed o hei abili ies o
app oxima e almos any complex non-linea unc ional ela ionship [70–72]. Machine
12
Lea ning algo i hms a e based on bo h supe ised and unsupe ised lea ning. Supe ised
Lea ning wo ks wi h labeled inpu da a, known as aining da a in a aining p ocess o
p edic ing unknown da a. Based on he known da a, he aining p ocess he eby con inues un il
he model achie es a desi ed le el o accu acy. Once he model is ained i can be used o
ans e his knowledge on new da a by gene alizing om he aining da a o unknown
examples. Supe ised lea ning p oblems can be u he g ouped in o classi ica ion and
eg ession p oblems. On he o he hand, o Unsupe ised Lea ning, he inpu da a is no
labeled and does no ha e a known esul . The model ies o ecognize a pa e n in he inpu
da a o lea n abou i and ex ac ules. This can be done h ough a ma hema ical p ocess o
sys ema ically educe edundancy o by o ganizing he da a by simila i y like h ough
Clus e ing and Associa ion.
Figu e 2: Machine Lea ning Chea Shee [73]
Some o he mos common ML algo i hms in Geospa ial Sciences and Mapping o In o mal
se lemen s a e Logis ical Reg ession, Decision T ees (DT), sel -o ganizing maps (SOM),
andom o es s (RF), suppo ec o machines (SVM) and a i icial neu al ne wo ks (ANN).
I ’s impo an o no e ha selec ing he bes algo i hm o a ask is qui e challenging since no
algo i hm ou pe o ms o he s in a gi en ask. Machine lea ning echniques ha e been and a e
s ill being used o ca y ou geospa ial analysis in a ious ields o clus e ing, classi ica ion
13
and p edic ion a ious en i onmen al and socioeconomic phenomena using di e en ypes o
da a.
2.5.1. Con olu ional neu al-ne wo ks
Con olu ional neu al-ne wo ks (CNNs) a e a b anch o a i icial neu al ne wo ks designed o
ecognize objec s in images based on hei abili y o de elop an in e nal ep esen a ion o a
wo-dimensional image [74]. The con olu ional neu al ne wo k is composed mainly o h ee
ypes o laye s i.e. Con olu ional Laye s, Pooling Laye s, Fully-Connec ed Laye s. The
Con olu ional laye s a e comp ised o il e s which a e he neu ons o he laye and a ea u e
map which is he ou pu o one il e applied o he p e ious laye . The pooling laye s down-
sample he p e ious laye s ea u e map by ollowing a sequence o one o mo e con olu ional
laye s wi h he in en ion o consolida e he ea u es lea ned and exp essed in hem. They a e
used o educe he size o he da a while main aining he mos impo an ea u es. Fully
connec ed laye s a e he no mal la eed- o wa d neu al ne wo k laye used a he end o he
ne wo k a e ea u e ex ac ion and consolida ion has been pe o med by he con olu ional
and pooling laye s, o c ea e inal non-linea combina ions o ea u es and o making
p edic ions by he ne wo k [75]. CNNs a e well sui ed o he ask o image classi ica ion
in he ield o emo e sensing, Howe e , CNNs also pose challenges when applied o
emo e sensing as i is o en di icul o imp ac ical o ob ain a la ge se o labelled
images, he model pe o ms poo ly and ends o o e i [74]. Such challenges can be cu bed
using echniques like Da a augmen a ion using o a ions and lips o inc ease he o al numbe
o aining images o u he a oid o e i ing p oblem [33].
20
In o mal se lemen s, hough mos in o mal se lemen buildings a e smalle han his spa ial
esolu ion o 10m*10m. The images o he da es in Table 2 we e selec ed based on pe cei ed
isually simila i y, quali y and minimal cloud co e .
Acquisi ion Da e
Bands Used
01-01-2016 4,3,2
23-08-2017 4,3,2
31-12-2019 4,3,2
Table 2: De ails o Sen inel-2 sa elli e images
3.2.3. Re e ence da a
The map selec ed o alida e egions mapped ou as in o mal egions in Kampala (Figu e 7)
was p epa ed by AcToge he (Ug) in 2014, does no include he slum se lemen s which ha e
ecen ly come up in he ci y. Howe e , i p o ides he loca ions o he slum se lemen s
manually delinea ed h ough Fields su eys and Public Pa icipa ion. The slums in Kampala
ci y a e no clus e ed a speci ic loca ions bu ha e sca e ed p esence all o e he ci y wi h
a ying sizes and shapes. The se lemen s a e loca ed along he main oads in elonga ed and
i egula shapes, along ailway lines and nea he lake. Un o una ely, ecen In o mali y maps
o Da -es Salaam we e di icul o come by.
Figu e 7: Dis ibu ion o In o mal Se lemen s in Kampala based on A e age Household Size
[97]

21
4. RESEARCH METHODOLOGY
The me hod consis s o h ee main phases (Figu e 8). Fi s phase consis s o en iching he
building ou line ea u es wi h geome ic and opologic pa ame e s,
The second phase en ails ho spo clus e ing and classi ica ion o hese cha ac e is ics o iden i y
in o mal se lemen s in simila con ex ci ies, and he inal phase in ol es spa io- empo al
moni o ing o in o mal se lemen s using sen inel-2 image y.
Figu e 8: Me hodology Flowcha
4.1. Da a En ichmen and Compu a ion o Pa ame e s
Be o e ca ying he clus e ing and classi ica ion p ocess, geome ic and opological measu es
o allow g ouping o ea u es in o di e en clus e s we e de e mined. The measu es chosen o
en iching he building ea u es we e size, shape and sho es dis ance o a neighbo ing building.
A building’s shape was desc ibed by he numbe o e ices i has i.e. e ex numbe (VN).
Mo e complex buildings ha e many e ices and is e sa. The size was desc ibed by
calcula ing i s a ea (A) [98,99]. The Nea es Neighbo Dis ance (NND) and was used o
desc ibe he opological ela ions o neighbo ing ea u es [100]. Buildings in in o mal
22
se lemen s end o be e y close o each o he wi h limi ed gap be ween hem. They a e also
small in size and ha e simple shapes like o ec angles o squa es houses. The no maliza ion
o compu ed a iables was ca ied ou since hey ha e a ying scales and o a oid in luence o
some a iables o e o he s du ing use in he machine lea ning algo i hms. The Min-max
no maliza ion app oach was used whe e all he alues we e mapped be ween [0–1].
𝑿󰆒= (𝑿𝑿𝐦𝐢𝐧)
(𝑿𝐦𝐚𝐱𝑿𝐦𝐢𝐧) (Min-Max No maliza ion Equa ion)
Whe e, X is an o iginal alue, X’ is he no malized alue, and Xmin, Xmax a e he minimum
and maximum alues o his pa icula p ope y.
4.2. In o mal Se lemen Buildings Clus e ing and Classi ica ion
In he i s s ep, clus e s a e de e mined based on simila i y o building ea u e cha ac e is ics
using ho spo clus e ing analysis. The clus e s a e hen eclassi ied o educe he numbe o
clus e s. I a building belongs o he same clus e based on he ea u es cha ac e is ics, i s
binned in one clus e and is e sa. This is done on he Kampala aining pa i ion. The second
s ep in ol es using di e en classi ie s o selec one ha sui s he aining pa i ion da a. The
selec ed classi ie is hem used o de e mine in o mali y egions in he Kampala Tes ing
Pa i ion and Da -es-Salaam da ase .
4.2.1. Clus e ing o In o mal Se lemen Buildings
As shown in chap e 2, in o mal se lemen a eas ha e building ea u es cha ac e ised by simple
shapes, small buildings and ha e limi ed gaps be ween hem.
In o de o de e mine he pa e n o spa ial dis ibu ion and whe e low and high alues o he
building ea u e cha ac e is ics a e g ouped, ho spo analysis based on he use o Ge is-O d Gi*
s a is ic was ca ied ou on he Kampala aining pa i ion da ase o iden i y s a is ically
signi ican ho and cold spo s [61]. Since ho spo analysis equi es he p esence o clus e ing,
he e is need o es o he p esence o clus e ing in he da ase by assessing spa ial
au oco ela ion o iden i y clus e ing wi hin he en i e da ase . The Spa ial Au oco ela ion
(Mo an’s) ool in A cGIS measu es spa ial au oco ela ion by simul aneously measu ing
ea u e loca ions and a ibu e alues. I ea u es ha a e close oge he ha e simila alues,
23
hen ha is said o be clus e ing, and is e sa. The Mo an’s I e u ns alues which include he
z-sco e and p- alue which will indica e i clus e ing is ound in he da a o no .
The Op imized Ho spo Analysis (OHSA) ool om A cGIS P o used o he ho spo analysis
is iden i ies s a is ically signi ican ho and cold spo s o mul iple es ing and spa ial
dependence using he using he False Disco e y Ra e (FDR) co ec ion me hod [101]. The
ea u es a e g ouped in o se en majo clus e s i.e. ea u es in he +/- 3 Gi_Bins we e s a is ically
significan a he 99% confidence le el; ea u es wi h 0 o he Gi_Bin field was no s a is ically
significan , hose in he +/2 bins eflec ed a 95% confidence le el, and ea u es in he +/1 bins
eflec ed a 90% confidence le el. Upon compu ing hese GiZsco es whe e cold spo s in all he
ea u e cha ac e is ics mos likely ep esen in o mal se lemen buildings, a c oss alida ion
es using Independen samples - es on he ho spo analysis esul s in o de o di e en ia e
be ween o mal and in o mal zones and o de e mine whe he he e is s a is ical e idence ha
he associa ed g oup means a e signi ican ly di e en be ween hem [102]. The GiZsco es o
bo h g oups; in o mal, and o mal egions a e compa ed and when he p- alue is less han
0.001, he null hypo hesis can be ejec ed and he esul s o GiZsco e can be illus a ed as
s a is ically signi ican [11].
The ea u es iden i ied as cold spo s we e hen eclassi ied and g ouped in o one class and all
he o he s as ano he class, which p oduces new eclassi ied esul s o he ea u e
cha ac e is ics o Size, shape and NND. The h ee eclassi ied esul s a e combined and i a
ea u e has all i s ea u e cha ac e is ics as cold spo s, i s g ouped as in o mal and i no , i s
clus e ed as o mal. This p oduces one esul an clus e da ase o he building ea u es which
shows bo h in o mali y and o mali y in he Kampala aining pa i ion da ase . These esul s
(especially he cold spo s) we e compa ed o a eas delinea ed as slums in Kampala gene a ed
by a collabo a ion be ween Slum Dwelle s In e na ional (SDI) and o he o ganiza ions [46, 89].
4.2.2. Classi ica ion o In o mal Se lemen s based on Building Cha ac e is ics
To p edic whe e in o mal se lemen egions a e based on building ea u es cha ac e is ics o
shape, size and NND, based on he clus e s om he aining pa i ion da ase , supe ised
machine lea ning classi ica ion was ca ied ou on da a o he same ci y (Kampala Tes ing
Pa i ion) and on da a o a di e en ci y (Da -es Salaam). Fi s ly, he clus e ing esul s we e
24
applied o ain, alida e and es se e al classi ie algo i hms in o de o selec one ha sui s
hese da ase s. Models we e buil using he py hon Sciki -lea n lib a y, aking ad an age o he
capabili ies and ea u es o his lib a y. These models included Logis ical Reg ession, Decision
T ee (DT), Mul ilaye Pe cep on (MLP), Random Fo es (RF) and Suppo Vec o Machine
(SVM). The choice o hese classi ie s in based on hei use in p e ious s udies o classi ie
buildings based on hei cha ac e is ics and also hei abili y o p o ide good accu acy wi h
e e ence o chap e 2. The sc ip in ol ed spli ing he T aining pa i ion da ase in o 70% o
aining and 30% alida ion. Classifica ion was pe o med i s on he aining da a and
accu acy measu es, including o e all accu acy, p ecision, ecall and -measu e we e no ed.
This was ca ied ou in o de o selec he bes classi ie o he da ase s. The selec ed classi ie
is hen used o p edic which ea u es belong o In o mal se lemen s in Kampala Tes ing
Pa i ion and Da -es Salaam.
4.3. Moni o ing he g ow h o In o mal Se lemen s
The sen inel- 2 image y a e p e-p ocessing and band composi ion we e clipped o he
Kampala Bounda y. The acqui ed in o mal se lemen egions om he classi ica ion phase
abo e p o ides o polygons ep esen ing in o mali y. We also assembled polygons o egions
ep esen ing h ee ca ego ies: “buil (wi hou in o mal)”, “ ege a ion”, and “wa e ”. All hese
egions we e gene a ed on he 2019 Image (Figu e 9). This is based on he assump ion ha he
OSM building ou lines used o classi y in o mali y we e as up- o-da e as o Oc obe 2019. All
he images we e hen sliced up in o equal-sized iles o 255*255 m o ensu e uni o mi y in he
da ase s and placed in olde s o “Tiles_2019”, “Tiles_2017” and “Tiles_2016” each wi h
5427 iles. The iles we e sa ed as i iles wi h a ached geo-in o ma ion which is equi ed o
plo he model p edic ions o he o iginal loca ions in he map.
25
Figu e 9: In o mal and Fo mal Tiles
The iles in olde Tile_ 2019 we e labelled based on he ou ca ego ies c ea ed based on hei
in e sec ion wi h he c ea ed polygons. All he iles belonging o “buil -up”, “ ege a ion”, and
“wa e ” we e g ouped in o one olde as Fo mal and he In o mal iles placed in an In o mal
Folde . Reg ouping he ou ca ego ies in o wo was mo e accu a e han aining a bina y
classi ie di ec ly om he a ailable da a. The iles we e hen spli in o aining (80%) and
es ing se s (20%) o model- alida ion o use in he CNN model.
A baseline CNN model based on gene al a chi ec u al p inciples o he Visual Geome y G oup
(VGG) on which o he models can be compa ed is es ablished. The CNN a chi ec u e in ol ed
s acking con olu ional laye s wi h small 3×3 il e s ollowed by a max pooling laye . These
laye s o m a block, and hese blocks can be epea ed whe e he numbe o il e s in each block
is inc eased wi h he dep h o he ne wo k such as 32, 64, 128, 256 o he i s ou blocks o
he model. Padding is used on he con olu ional laye s o ensu e he heigh and wid h shapes
o he ou pu ea u e maps ma ches he inpu s. This unc ion can hen be cus omized o de ine
di e en baseline models, e.g. e sions o he model wi h 1, 2, o 3 VGG s yle blocks. The
model was i ed wi h s ochas ic g adien descen , a conse a i e lea ning a e o 0.001 and a
momen um o 0.9. Since he p oblem was a bina y classi ica ion ask i.e Fo mal and In o mal,

26
he p edic ion o one alue o ei he 0 o 1 was equi ed. An ou pu laye wi h 1 node and a
sigmoid ac i a ion was used and he model op imized using he bina y c oss-en opy loss
unc ion. One-block (32 il e s), wo-block (32 and 64 il e s) and h ee-block (32,64 and 128
il e s) VGG models we e all compa ed on he da ase . Two app oaches o add ess o e i ing
o he aining da ase : d opou egula iza ion and da a augmen a ion we e explo ed o selec
he bes sui ed one. Upon selec ing he bes model wi h he adequa e model pa ame e s,
P edic ions we e pe o med on he Independen ile da ase s o “Tiles_2017” and
“Tiles_2016” o au oma ically p edic in o mal se lemen iles ou o all he iles. A polygon
laye was hen buil o he new in o mali y iles. This p edic ion s ep leads o iles ha a e
ei he o mal o no . Polygons o he image ile Bounda ies a e c ea ed and hose ha belong
o in o mal g oup a e o e laid on o he map o isual in e p e a ion.
27
5. RESULTS
This chap e desc ibes he implemen a ion de ails o he me hodology and p esen s he esul s
o his s udy. The sou ce code o his implemen a ion can be ound a
h ps://gi hub.com/Bakked9/Mas e sThesis.
5.1. Clus e ing Analysis
5.1.1. Clus e ing Indices o Building Cha ac e is ics
The Mo an's Indices o he A ea, shape and NND a e all close o 0.2, and ha e p- alues o 0.0
(Table 3). The z-sco e is a s anda d de ia ion which measu es how many SDs away an elemen
is om he mean, while he p- alue is a measu e o p obabili y ha a andom p ocess c ea ed
he obse ed pa e n. A small p- alue is an indica o ha he spa ial pa e n is no andom and
is e sa. A posi i e Mo an’s I esul indica es ha neighbo ing a eas o poin s a e simila wi h
espec o a ibu e alues, while nega i e Mo an’s I shows ha nea by egions a e less simila
in a ibu es han one would expec in a andom pa e n [103]. This goes o show ha clus e ing
exis s wi hin he da ase wi h espec o he measu emen a iables and hence Ho spo analysis
can be ca ied ou on he da a.
Va iable Mo an's Index Expec ed Index Va iance z-sco e p- alue
Nea es Dis ance
0.257656
-0.000017 0.000139 21.848243 0.000000
A ea 0.278887 -0.000017 0.000139 23.696816 0.000000
Shape 1.336825 -0.000017 0.000139 113.285603
0.000000
Table 3: Spa ial Au oco ela ion (Mo an's I) Resul s
5.1.2. Op imized Ho spo Analysis
The op imized ho spo analysis esul ed in o Gi_Bin fields which iden ified he s a is ically
significan ho spo s, along wi h he non-significan and cold spo s, indica ing he ype o
clus e s o he ea u e cha ac e is ics. In he case o he T aining pa i ion, he Gi_Bin field
showed ha pa ches sp ead a ound he selec ed a ea was cha ac e ized by cold spo s, non-
significan ypes, and ho spo s ypes ha a e dis ibu ed allo e (Figu e 10). The a eas
iden i ied as non-significan clus e ypes p o ide some so o bounda y be ween he cold and
28
ho spo s. Whe eas he cold spo s we e loca ed in a small a ea mainly on he no h and cen al
pa s, he ho spo clus e s we e sp ead ou in on he no h, sou h, eas and wes sides.
Figu e 10: OHSA Resul s Maps o Size, Shape and NND
5.1.3. The Associa ion be ween he Cold spo s and In o mal se lemen s
Table 4 illus a es he esul s o he - es analysis, using a 95% con idence le el o each ea u e
cha ac e is ic. Since he Sig (2-Tailed) alues i.e. he p- alue o he GiZsco e and Nneighbou s
p edic o s a e e y small i.e. p<0.001, we ejec he null hypo hesis o Le ene's es and
conclude ha he a iances in he GiZsco e and Nneighbou s p edic o s o Fo mal is
signi ican ly di e en om ha o In o mal. The In o mal g oups mean numbe s o neighbo s
a e la ge han hose o he o mal a eas. The mean GiZsco es a e he in o mal a eas a e also
smalle han hose o he o mal a eas. This shows ha he in o mal egions a e mo e likely o
be cold spo s wi h low alues o Shape, size and NND.
29
SIZE(AREA)
G oup
N
Mean
S d.
De ia ion
S d. E o
Mean
Sig.(2
-
ailed)
GiZSco e
ColdSpo (In o mal) 104884 -4.4855 2.0227 0.0062 0.000
Ho Spo (Fo mal) 36868 3.6859 1.8595 0.0097
Nneighbo s ColdSpo (In o mal) 104884 958.00 302.407 .934 0.000
Ho Spo (Fo mal) 36868 363.13 129.434 .674
NEAREST NEIGHBOUR DISTANCE (NND)
G oup
N
Mean
S d.
De ia ion
S d. E o
Mean
Sig.(2
-
ailed)
GiZSco e
ColdSpo (In o mal) 123467 -5.6911 2.8813 0.0082 0.000
Ho Spo (Fo mal) 41942 5.1848 3.3074 0.0161
Nneighbo s
ColdSpo (In o mal) 123467 936.37 281.848 .802 0.000
Ho Spo (Fo mal) 41942 344.97 119.569 .584
SHAPE (VERTEX NUMBER)
G oup
N
Mean
S d.
De ia ion
S d. E o
Mean
Sig.(2
-
ailed)
GiZSco e
ColdSpo (In o mal) 129377 -4.8803 1.9626 0.0055 0.000
Ho Spo (Fo mal) 34552 5.8729 4.6398 0.0250
Nneighbo s ColdSpo (In o mal) 129377 850.26 319.712 .889 0.000
Ho Spo (Fo mal) 34552 512.44 286.337 1.540
Table 4: Independen samples - es analysis Resul s
Cold spo s in his analysis ep esen a eas ha ha e low alues o A ea, Shape and NND.
In o mal se lemen s a e cha ac e ised by buildings ha ha e simple shape, small is size and
a e densely loca ed in a pa icula loca ion i.e. sho NNDs be ween polygons (see igu e 10).
Wi h his, he cold spo s esul ing om he OHSA a e conside ed o be loca ions wi h
in o mali y based one he building ypologies used o cha ac e ise hem.
To simpli y he da a o u he analysis, all he OHSA esul s we e classi ied o bin he da a
poin s in o wo classes i.e. “In o mal” and “Fo mal”. This was done h ough eclassi ica ion o
he Gi_bin esul s wi h a h eshold o -2 o lowe (95% cold spo con idence le el) as
In o mali y and he es as o mali y. As shown in igu e 11 and 12, he egions ha iden i ied
as In o mal sha e common loca ions ac oss he map wi h espec o he building ypologies.
The esul s we e combined o highligh only hose a eas ha had been classi ied as in o mali y
in all he ypologies. The esul an da ase was hen used as a aining se o he Classi ica ion
s ep.
36
Figu e 16: Change in In o mal Se lemen Regions in Kampala. This shows In o mal iles ha exis ed in
Janua y 2016, new in o mal iles ha had de eloped by Augus 2017 and also by Decembe 2019.

37
6. DISCUSSION
6.1. Discussion
This s udy p esen ed app oaches o classi y in o mali y egions based on building ou line
cha ac e is ics and moni o ing g ow h o in o mal se lemen s o e ime by execu ing CNNs
on High esolu ion sa elli e image y. Fi s ly, we highligh ha OSM building ea u e
cha ac e is ics i.e. size and shape o building ou line, and dis ance o nea es building can be
used o di e en ia e be ween o mal and in o mal buildings. In he app oach, he geome ic
and opologic measu es p esen ed in his esea ch we e clus e ed based on he alues high o
low. As an impo an aspec o he e alua ion, he ans e abili y o he ob ained clus e s om
aining se o es da a was in es iga ed. Fi s ly, he esul s we e applied o he es ing da a o
he same ci y and hen o ano he ci y. 108,390 o 429,270 buildings (25.25%) we e classi ied
as in o mal se lemen buildings in Kampala while 188,728 o 971,008 buildings (19.44%) in
Da -es Salaam we e classi ied as in o mal se lemen buildings (Figu e 13). The e was a
dec ease in Random Fo es classi ie model pe o mance on he Kampala Tes Pa i ion and
Da -es Salaam may be due o di e ences in he cha ac e is ics o buildings in e y u ban a eas,
o he ac ha mo e da a we e a ailable in Da -es -Salaam. I ’s impo an o no e ha he
accu acy alues we e consis en ly abo e 0.75, sugges ing e y good disc imina o y
pe o mance i espec i e o he ci y. The a ia ion in building ypologies used du ing his
analysis (shape, size and spacing) played an impo an ole du ing he classi ica ion o
in o mali y and o mali y e en hough hese cha ac e is ics a y acco ding o geog aphical
loca ion [93]. Though he mo phological na u e o in o mal se lemen s a ies ac oss he
global, hey s ill ba e some simila i ies in cha ac e is ics. This could be he eason why he
same model could be applied in a di e en ci y and p oduce dis inc esul s. Compa ed o i s
a eal co e age, he e a e ewe in o mal se lemen buildings in Da es Salaam. O e he yea s,
a dec ease in he popula ion li ing in Slums in Tanzania has been dec easing wi h a sha p
dec ease obse ed om 2011 e en wi h apid popula ion g ow h o e ime (Figu e 17). This is
p obably due o s a egies by he Tanzania go e nmen o shi om egula ly demolished
homes in in o mal se lemen s o awa ding i les could be one o he easons o a dec ease in
in o mali y in he ci y. The MKURABITA P og amme i s launched in Da es Salaam, aims
a ans o ming p ope y and businesses held in he in o mal sec o in o legal en i ies ha a e
oo ed i mly in he o mal sec o [104].
38
Figu e 17: Tanzania - Popula ion Li ing In Slums (% O U ban Popula ion) [[105]]
The expe imen a ions o Using CNN on Sen inel-2 e alua es shows p omising esul s on
disc imina ing In o mal om o mal se lemen s o e ime. Howe e , Seasonal a ia ions
be ween he images p e en ed he deep lea ning model om ecognizing ce ain In o mal
Se lemen s. Tes ing he model on new mul i- empo al da ase s causes he model pe o mance
o dec ease as we mo e away om he aining se ’s sensing ime. The pe o mance o he
model is bound o deg ade as we mo e u he away om he aining pe iod. Upon compa ing
he de elopmen o he slums in Kampala ci y using he ime slide in Google Ea h om he
yea 2014 o he da es a which sa elli e images a e downloaded, change obse a ions can be
made. I can be seen ha since 2014, he buil densi y o slums has inc eased a p e-exis ing
loca ions and smalle new pa ches ha e eme ged a subu ban a eas o he ci y. Compa ed o
he la ge a eas o al eady exis ing slums, hese new se lemen s a e qui e smalle and hence
could be igno ed du ing p edic ion on he image iles due o mixed classes wi h ege a ion and
o mal a eas.
To e alua e he esul s ob ained, he p edic ion Accu acy ob ained om he Baseline VGG3 +
Da a Augmen a ion CNN Model (90.3%) on he sen inel-2 image y is a e y good esul s
based on he spa ial esolu ion o he images. In [106], Fede ico .B and Damián .S also de ec
in o mal se lemen s using sen inel-2A image iles. They employed he use o Remo e Sensing
Classi ie o P edic iles ha belong o in o mal se lemen s. They ecommend he use o deep
lea ning echniques, like con olu ional neu al ne wo ks o imp o e he accu acy o he
classi ica ion. This indica es ha he CNN p o ides be e classi ica ion accu acy especially
39
because i ’s an image based classi ie . On ano he no e, he use o building ou line
cha ac e is ics like size, shape and Nea es Neighbou dis ance p o ides o a lo mo e insigh
on he na u e and mo phology o an in o mal se lemen .
In es iga ions on p edic ing in o mal se lemen s using oad in e sec ions om OSM da a [20]
showed ha OSM da a can be used in his scena io. Howe e , some o he limi a ions o his
s udy is ha some in o mal se lemen s ha e oads ha a e no mapped on OSM which makes
hei de ec ion di icul . This is whe e he use o Building ea u e cha ac e is ics, as shown in
his esea ch a e use ul. The cha ac e is ics help be e delinea e in o mal se lemen s. An e en
be e al e na i e would be he combina ion o building ea u e cha ac e is ics and densi y o
oad in e sec ions o iden i y hese in o mal se lemen s. The use o Mul ilaye Pe cep on
(MLP) on ho spo analysis GiZsco e and Nneighbou s o p edic in o mal se lemen s p o ed
a good enough classi ie , howe e in his esea ch, hough MLP pe o med well, Random
Fo es Classi ie was a be e classi ie o Building ea u e cha ac e is ics o p edic
in o mali y.
6.2. Limi a ions
While he s udy p oduced good esea ch indings, he e a e se e al limi a ions and
oppo uni ies o u he esea ch Addi ional ec o da a o land pa cels, small adminis a i e
dis ic uni s, ci y s unc ional zones, o land use da a could be in eg a ed o imp o e he
c ea ion o desi ed op imal shapes o image objec s o compac homogeneous buil -up a eas
o buil -up densi y analysis. I a ailable in accu a e up- o-da e o m, ec o laye o building
oo p in s could be used o buil -up densi y calcula ion, wi hou he need o land co e
classi ica ion and building ex ac ion om he sa elli e image da a. This laye would ep esen
only buildings, wi hou oads o o he man-made u ban s uc u es. Howe e , his da a is no
always eely a ailable in accu a e and up- o-da e o m, and his app oach akes ha in o
conside a ion. The lack o adequa e da a o es he model on o he ci ies besides he wo
p esen ed was expe ienced. This model wo ked o hese wo ci ies because he e bo h ha
OSM da a almos accu a ely a ailable. This is no he case o mos o he ci ies in he global
sou h ha a e engul ed by in o mali y.
40
7. CONCLUSION AND FUTURE WORKS
The main esea ch Aim o his esea ch wo k was o in eg a e OSM da a and sen inel-2
image y o classi ying and moni o ing he g ow h o in o mal se lemen s. To achie e his,
he esea ch ques ions we e in es iga ed:
1. How can we exploi he po en ial o using buildings ou line cha ac e is ics such as size
and shape o di e en ia e In o mal se lemen s om Fo mal Se lemen s?
The esul s om he ho spo clus e ing analysis demons a ed ha in o mal se lemen s
can be di e en ia ed om o mal a eas based on he use o Building ea u e
cha ac e is ics ha is shape, size and NND. The in o mal se lemen buildings a e
cha ac e ized by low alues (cold spo s) o each cha ac e is ic.
2. Is i possible o p edic in o mal a eas in a ci y by unde s anding housing in o mali y in
o he ci ies o simila con ex using buildings ou line cha ac e is ics and machine
lea ning?
Also i s obse ed ha hough mo phologically di e en , slums sha e some
cha ac e is ics like he na u e o building ou lines. This is shown by he ans e abili y
o he classi ie ained on one da ase o p edic in o mal se lemen s in new da ase s
in he same ci y and in a di e en ci y.
3. Wha is he mos app op ia e Machine Lea ning echnique based on accu acy o p edic
in o mal a eas in a ci y based on buildings ou line cha ac e is ics?
The mos app op ia e ML echnique is he Random Fo es classi ie . I p o ed i s
e ec i eness in a b oad ange o applica ions o Geospa ial echnologies. As a non-
pa ame ic me hod, he key p ope y o Random Fo es is i s capabili y o handle
di e en s a is ical dis ibu ions o ea u es, which was one o he main challenges o
his s udy. This make Random Fo es a sui able algo i hm o ou bina y classi ica ion
and p edic ion p oblem.
4. How can we exploi he po en ial o eely a ailable Sen inel-2 sa elli e image y wi h
ad anced machine lea ning o es ima e he g ow h o In o mal se lemen s?
41
Sen inel 2 images, despi e ha ing a spa ial esolu ion o 10m, can be used o in o mal
se lemen mapping when coupled wi h Ad anced Machine Lea ning Algo i hms like
CNNs.
We sugges ha his esea ch a ea could be explo ed mo e and u u e esea ch could be done,
building and imp o ing on he esul s wi h emphasis on a be e accu a e ep esen a ion o
In o mal se lemen s. Fu he mo e, o he OSM ea u es and pa ame e s such as Roads and
accessibili y wi hin he in o mal se lemen s o o he s could be used o be e iden i y whe e
he in o mali y egions could be. This is because In o mal se lemen s a e usually cha ac e ized
by na ow and sho oad segmen s his nume ous dangles an he end o he oads. O he
pa ame e s like p oximi y o haza dous a eas like we land and sewe age channels should be
conside ed. This howe e , would howe e equi e much mo e de ailed and complex land co e
classi ica ion scheme as a sou ce o in o ma ion o his analysis, including iden i ica ion o ,
ege a ion ypes, di e ence be ween ag icul u al ba e soil and ba e soil a eas in u ban a ea o
a cons uc ion si es and so on. I a ailable, Digi al Su ace Model (DSM) could be used o mo e
accu a ely iden i y and map in o mal se lemen s because inclusion o he hi d dimension o
Ele a ion would help highligh mo e dis inguishing cha ac e is ics o in o mal se lemen
buildings.
Ne e heless, he con ibu ion o he empo al dimension o in o mal se lemen mapping
in es iga ed in his esea ch equi es u he es ing wi h la ge da ase s and longe ime se ies.
Wi h his mind, we hink he posi i e esul s achie ed in his esea ch a e wo h building upon
in u u e s udies o u he in es iga e he empo al domain as an inpu o in o mal se lemen
mapping and classi ica ion models.

42
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52
8. ANNEXES
8.1. Independen Samples T-Tes s On Ho spo Analysis GiZSco es and Nneighbo s

53
8.2. Plo s o Accu acy and Loss o Some CNN Models - T ain (blue) and Tes
(o ange) da ase s.
8.2.1. 1-VGG
8.2.2. 3-VGG
54
8.2.3. Baseline VGG3 + Da a Augmen a ion
8.2.4. P e-T ained VGG16
55
8.3. In o mali y Regions o Kampala in 2016 ( op le ), 2017 ( op igh ) and 2019
(bo om)
01-01-2016
23-08-2017
31-12-2019
56