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Generalisation and data selection
Mary Spence MBE Global Mapping Ltd
Better Mapping 2017
Better Mapping 2017
BUT . . .
A map can’t show everything that’s on the ground
SO . . .
There has to be compromise — a process that we call cartographic generalisation
What is a map? A map is a symbolised image of geographic
reality
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What is generalisation? Generalisation is the process of simplifying the
complexity of the real world so that it can be shown clearly at reduced scales.
Why is it necessary? Generalisation is necessary because it is
impossible to represent all objects of a landscape at smaller scales – a photographic reduction would lead to an illegible map.
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What influences generalisation?
design how the features are symbolised
scale less space on the map to include all the features
purpose a map should focus on the information that is essential to the user
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What happens as scale reduces?
crowding too many features to show in a smaller area
conflict features overlap or become indistinguishable
Result? a cluttered, unintelligible mess of data
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44
43
42
41
40
39
38
37
36
3535a
34Isle of
W
R i
Morecambe Bay
Pe
nn
i
Cu m
br i
an
Scafell Pike978m
Helvellyn950m
Skiddaw931m
Cross Fell893m
BassenthwaiteLake
Cow GreenReservoir
UllswaterDerwent WaterCrummock
Water Haweswater
ReservoirWast
Water
WindermereConiston
Water
South TyneEd
Lune
A69
A6
A595A596
A5092
A595A66
A66
A685
A591
A590
A590
A66
A65
A687
A683
A65
M6
M6
M6
CUMBRIA
Haltwhistle
WetheralSilloth
AlstonAspatriaMaryport
PenrithCockermouthKeswick Appleby-in-
Westmorland
Egremont Kirkby StephenAmblesideSeascale Gosforth
SedberghNewbyBridge
MilnthorpeMillomGrange-
over-SandsCarnforth IngletonClapham
Wigton
GrasmereWindermereConiston
UlverstonDalton-in-Furness
BootleBroughtonin Furness
Kirkby Lonsdale
ShapGlenridding
Burton-in-Kendal
Tebay
BroughTemple
Sowerby
St John'sChapel
Hornby
Hawes
Settle
Horton inRibblesdale
BlanchlandAllendale
TownLambley
Melmerby
ButtermereBraithwaite
Kirkbride
BothelCaldbeck
Dalston
GreystokeStainton
Warcop
Ravenglass
Workington
Kendal
Barrow-in-Furness
Carlisle
Morecambe
50% reduction
44
43
42
41
40
39
38
37
36
3535a
34
S
S
S
S
St Bees Head
Isle ofWalney
R i bb
l wa
y
Fi r t h
Morecambe Bay
Pe
nn
in
eCu m
b r ia
n M
ou
nt a
i ns
Scafell Pike978m
Helvellyn950m
Skiddaw931m
Cross Fell893m
BassenthwaiteLake
Cow GreenReservoir
UllswaterDerwent
WaterCrummockWater
HaweswaterReservoirWast
Water
WindermereConiston
Water
South Tyne
Eden
Lune
A69
A6
A595A596
A5092
A595
A66
A66
A685
A591
A590
A590A66
A65
A687
A683
A65
M6
M6
M6
CUMBRIA
HaltwhistleDalbeattie
WetheralSilloth
AlstonAspatria
Maryport
PenrithCockermouth
KeswickAppleby-in-
Westmorland
EgremontKirkby Stephen
Ambleside
SeascaleGosforth
Sedbergh
NewbyBridge
MilnthorpeMillomGrange-
over-SandsCarnforth
IngletonClapham
Wigton
Grasmere
WindermereConiston
Ulverston
Dalton-in-Furness
Bootle Broughtonin Furness
Kirkby Lonsdale
ShapGlenridding
Burton-in-Kendal
Tebay
Brough
TempleSowerby
St John'sChapel
Hornby
Hawes
Settle
Horton inRibblesdale
Blanchland
AllendaleTownLambley
Auchencairn
Melmerby
Buttermere
Braithwaite
Kirkbride
Bothel Caldbeck
Dalston
Greystoke
Stainton
Warcop
Ravenglass
Workington
Whitehaven
Kendal
Barrow-in-Furness
Carlisle
Morecambe
original
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50% reduction
original
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50% reduction (enlarged)original
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What is the purpose of the map?
what is it for? navigation, reference, analysis
what message does it need to communicate?
it is not safe to sail here, there are more of something here than there
how will it be delivered?
paper, computer screen, smart phone
who wants it? cyclist, walker, boater
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Simplification starts with feature selection — deciding what
elements are required to be shown on the map
AND . . .those decisions relate to the purpose of the map
Generalisation is the process of simplifying the complexity of the real world so that it can be shown clearly at reduced scales.
Better Mapping 2017
leave out small variations
group like elements
simplification
merging
emphasise important features
exaggeration
avoid overlapping detail displacement
Generalisation
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k
k
k
k
k k
k
simplification
exaggeration
displacement
merging
Generalisation
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Group similar features to a new classification
Classification
. . . qualitative attributes
A
E
A
E
A
E
. . . quantitative attributes
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Form change
. . . from area fill to symbol
AE
. . . from complex line to simple line
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. . . focus on the key information relative to the map’s purpose
. . . minimise clutter
. . . maintain legibility of key information as scale reduces
. . . maximise communication
Generalisation should
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who the map is for
what the map is for
what the map has to communicate
the scale of the map
the conditions under which the map will be viewed
the medium of delivery
Summary
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Potter
Susquehanna
Tioga
Columbia
LackawannaWyoming
Sullivan
Bradford
Chemung
Broome
Allegany
Schuyler
Steuben
Tioga
Tompkins
Chenango
YatesCortland
Wyoming
Livingston
SenecaOntarioGenesee Monroe
Cayuga
CapeMayFrederick
BaltimoreCarroll
Harford Cecil
Washington
Atlantic
Cumberland
SalemNewCastle
Glouc.Camden
Adams
Phil.
Fulton
Ocean
Burlington
York
Chester
Franklin
LancasterCumberland
Bedford
Mercer
Montgomery
Monmouth
Lebanon
Bucks
PerryDauphin
Berks
Juniata
Cambria
Middlesex
Union
HuntingdonBlair
Suffolk
Somerset HunterdonLehigh
Queens
Mifflin
Snyder
Nassau
North-
umberland
Schuylkill
Northampton
Morris
Bergen
Carbon
Union Montour
Passaic
ClearfieldCentre
RocklandWestchester
Luzerne
Dukes
Clinton
Putnam
Lycoming
Warren
SussexPike
Cameron
Orange
Lackawanna
MiddlesexNewHaven
Fairfield
Newport
NewLondon
Kent
Wayne
Washington
Sullivan
WindhamTolland
Hartford
Litchfield
Barnstable
Dutchess
Bristol
Ulster
Plymouth
HampdenGreene Columbia
Delaware
HampshireBerkshire
SchoharieOtsego
Hudson
Kings
Providence
Du Bois
Lewistown
Gettysburg
Wellsboro
Endwell
Geneva
Point Pleasant
Towanda
WoodstockCanaan Winsted
Torrington Willimantic
Middletown
Norwich
Northampton
Housatonic Westfield
TauntonWareham
Edgartown
Havrede Grace
Auburn
WarsawPenn Yan
Cortland
Dansville
Norwich
Ravena
Cooksburg
Stamford
WatkinsGlen
Chatham
Greene
BainbridgeWalton
Corning
Wellsville
Owego
Downsville
Hancock Liberty
Monticello
Goshen
Warwick
Greenport
East Hampton
Southampton
Elkland
Port Allegany
Coudersport
Hop Bottom
Blossburg MeshoppenCarbondale
Dushore
EmporiumRalston Noxen
Milford
Brockway Jersey Shore
Lock Haven
Stroudsburg
Clearfield
Bangor
Pottsville
Tyrone
BarnesboroMillersburg
Mount Union
Martinsburg
Doylestown
CarlisleLititz
Shippensburg
Somerset
West Chester
Hanover
Newport
Westerly
Salem
BridgetonMillville
Smyrna
Nantucket
Elkton
Hancock
Rising Sun
Westminster
Berlin
Dover
Flemington
Franklin
Frenchtown
Hammonton
Mullica Hill
Ocean City
Pleasantville
Seaside Park
Somerville
Tuckerton
BataviaAvon
Belmont
Canandaigua
Catskill
EllenvilleFranklinville
Livingston
Manor
Medford
Millbrook
Millerton
Port Jervis
Richmondville
Riverhead
St James
Candor
Athens
Benton
Berwick
Bloomfield
Broomall
CentralCity
Driftwood
East Greenville
Galeton
Hallstead
Hamburg
HerndonMcClure
McConnellsburg
MountJewett
New Freedom
New Milford
Quarryville
Renovo
Troy
Wakefield
Newark
Tamaqua
Ephrata
MiltonSt Marys
Huntingdon
MiddletonPeekskill
Bath
Newark
Geneseo Cranston
Milford
Waretown
Ship Bottom
Ithaca
Kingston
Newburgh
Pottstown
Oneonta
Shamokin
Bedford
Hornell
Princeton
Armonk
Olean
Windsor Locks
Long Branch
Long Beach
New City
Norristown
ChesterColumbia
State College
New Bedford
New London
Fall River
Altoona
Atlantic City
Binghamton
Easton
Elmira
Hagerstown
Hazleton
Holyoke
Johnstown
Lebanon
Vineland
Wilkes-Barre
Williamsport
WilmingtonYork
Reading
Lancaster
New Brunswick
ScrantonNorwalk
Warwick
Levittown
CamdenHarrisburg
Stamford
Yonkers
Allentown
Bridgeport
Springfield
Waterbury
New HavenDanbury
New Britain
Elizabeth
Trenton
Paterson
JerseyCity
Newark
Bayonne
PoughkeepsieHartford
New York
Philadelphia
ProvidenceCape
Cod Bay
Nantucket Sound
Long Island
Martha's
Vineyard
NEW YORK
NEW JERSEY
MARYLAND
CONN.
PENNSYLVANIA
R.I.
Potter
Susquehanna
Tioga
Columbia
LackawannaWyoming
Sullivan
Bradford
Chemung
Broome
Allegany
Schuyler
Steuben
Tioga
Tompkins
Chenango
YatesCortland
Wyoming
Livingston
SenecaOntarioGenesee Monroe
Cayuga
CapeMayFrederick
BaltimoreCarroll
Harford Cecil
Washington
Atlantic
Cumberland
SalemNewCastle
Glouc.Camden
Adams
Phil.
Fulton
Ocean
Burlington
York
Chester
Franklin
LancasterCumberland
Bedford
Mercer
Montgomery
Monmouth
Lebanon
Bucks
PerryDauphin
Berks
Juniata
Cambria
Middlesex
Union
HuntingdonBlair
Suffolk
Somerset HunterdonLehigh
Queens
Mifflin
Snyder
Nassau
North-
umberland
Schuylkill
Northampton
Morris
Bergen
Carbon
Union Montour
Passaic
ClearfieldCentre
RocklandWestchester
Luzerne
Dukes
Clinton
Putnam
Lycoming
Warren
SussexPike
Cameron
Orange
Lackawanna
MiddlesexNewHaven
Fairfield
Newport
NewLondon
Kent
Wayne
Washington
Sullivan
WindhamTolland
Hartford
Litchfield
Barnstable
Dutchess
Bristol
Ulster
Plymouth
HampdenGreene Columbia
Delaware
HampshireBerkshire
SchoharieOtsego
Hudson
Kings
Providence
Du Bois
Lewistown
Gettysburg
Wellsboro
Endwell
Geneva
Point Pleasant
Towanda
WoodstockCanaan Winsted
Torrington Willimantic
Middletown
Norwich
Northampton
Housatonic Westfield
TauntonWareham
Edgartown
Havrede Grace
Auburn
WarsawPenn Yan
Cortland
Dansville
Norwich
Ravena
Cooksburg
Stamford
WatkinsGlen
Chatham
Greene
BainbridgeWalton
Corning
Wellsville
Owego
Downsville
Hancock Liberty
Monticello
Goshen
Warwick
Greenport
East Hampton
Southampton
Elkland
Port Allegany
Coudersport
Hop Bottom
Blossburg MeshoppenCarbondale
Dushore
EmporiumRalston Noxen
Milford
Brockway Jersey Shore
Lock Haven
Stroudsburg
Clearfield
Bangor
Pottsville
Tyrone
BarnesboroMillersburg
Mount Union
Martinsburg
Doylestown
CarlisleLititz
Shippensburg
Somerset
West Chester
Hanover
Newport
Westerly
Salem
BridgetonMillville
Smyrna
Nantucket
Elkton
Hancock
Rising Sun
Westminster
Berlin
Dover
Flemington
Franklin
Frenchtown
Hammonton
Mullica Hill
Ocean City
Pleasantville
Seaside Park
Somerville
Tuckerton
BataviaAvon
Belmont
Canandaigua
Catskill
EllenvilleFranklinville
Livingston
Manor
Medford
Millbrook
Millerton
Port Jervis
Richmondville
Riverhead
St James
Candor
Athens
Benton
Berwick
Bloomfield
Broomall
CentralCity
Driftwood
East Greenville
Galeton
Hallstead
Hamburg
HerndonMcClure
McConnellsburg
MountJewett
New Freedom
New Milford
Quarryville
Renovo
Troy
Wakefield
Newark
Tamaqua
Ephrata
MiltonSt Marys
Huntingdon
MiddletonPeekskill
Bath
Newark
Geneseo Cranston
Milford
Waretown
Ship Bottom
Ithaca
Kingston
Newburgh
Pottstown
Oneonta
Shamokin
Bedford
Hornell
Princeton
Armonk
Olean
Windsor Locks
Long Branch
Long Beach
New City
Norristown
ChesterColumbia
State College
New Bedford
New London
Fall River
Altoona
Atlantic City
Binghamton
Easton
Elmira
Hagerstown
Hazleton
Holyoke
Johnstown
Lebanon
Vineland
Wilkes-Barre
Williamsport
WilmingtonYork
Reading
Lancaster
New Brunswick
Scranton
Cheektowaga
Norwalk
Warwick
Levittown
CamdenHarrisburg
Stamford
Yonkers
Allentown
Bridgeport
Springfield
Waterbury
New HavenDanbury
New Britain
Elizabeth
Trenton
Paterson
JerseyCity
Newark
Bayonne
PoughkeepsieHartford
New York
Philadelphia
ProvidenceCape
Cod Bay
Nantucket Sound
Long Island
Martha's
Vineyard
A
p
p
a
la
c
h
ia
n
M
ou
nt
ai
ns
NEW YORK
NEW JERSEY
MARYLAND
CONN.
PENNSYLVANIA
R.I.
Better Mapping 2017
Snowdon(Yr Wyddfa)
1085m
Cadair Idris893m
1064m
Glyder Fawr1001m
e n i n s u l a
LlynTrawsfynydd
Conwy
A487
A44
A487
A487
A470
A5
A487
A470
GWYNEDD
W A L E S( C Y M R U )
BethesdaLlanrwstCaernarfon
PorthmadogCriccieth Ffestiniog
Pwllheli
Dolgellau
Machynlleth
Aberystwyth
Devil's Bridge(Pontarfynach)
Llanberis
Betws-y-Coed
Abersoch
Tremadog
BlaenauFfestiniog
Trawsfynydd
Llanwnda
Penygroes
LlanaelhaearnBeddgelert
Barmouth(Abermaw)
Harlech
LlanelltydDyffryn
Ardudwy
EglwysFach
Tywyn
Aberdovey(Aberdyfi)
Llwyngwril
Bryncrug
Cemmaes
A n g l e s e y
C a r d i g a nB a y
C a e r n a r f o nB a y
Ca
mb
ri
an
M
Snowdon1085m
Cadair Idris893m
AranFawddwy
905m
CarneddLlewelyn1064m
l e y n P e n i n s u l a
LlynCelyn
LlynBrianne
Lake Vyrnwy
Teifi
Severn
A487
A483
A44
A487
A487
A470
A5
A55
A470
A55
W A L E S
MenaiBridge
Bangor
LlanrwstCaernarfon
Nefyn PorthmadogBalaCriccieth
Ffestiniog
Pwllheli
Dolgellau
Machynlleth
Aberystwyth
Devil'sBridgeLlanrhystud
AberaeronNew Quay
SynodInn
Aberporth
HolyheadBeaumaris
Rhosneigr
Llanberis
Llandudno
Abergele
LlanfairTalhaiarn
Betws-y-CoedPentrefoelas
Abersoch
BlaenauFfestiniog
Trawsfynydd
Llanaelhaearn
Barmouth
Harlech
TywynAberdovey
Llangurig
LlandrindodWells
Tregaron
DinasMawddwy
Conwy
ColwynBay
BardseyIsland
HolyIsland
A n g l e s e y
C a e r n a r f o nB a y
Ca
mb
r ia
n M
ou
nt a
i ns
B r e co n B e a co n s
Snowdon1085m
A487
A483
A44
A487
A487
A470
A5
A458
A40
A55
A470
A494
A55
W A L E S
St AsaphBangor
Caernarfon
Corwen
LlangollenNefyn Porthmadog
Bala
Ffestiniog
Pwllheli
Dolgellau
LlanfairCaereinion
Machynlleth
Newtown
Aberystwyth
RhayaderAberaeron
New Quay
Lampeter
NewcastleEmlyn
LlandeiloCarmarthen
Holyhead
Amlwch
Llandudno
DenbighBetws-y-Coed
AbersochBarmouth
Aberdovey
Llangurig
BuilthWells
Tregaron
Cardigan
LlandoveryBrecon
ConwyRhylColwyn
BayBirkenhead
Thank you
Mary Spence MBE Global Mapping Ltd