APC Part I Workshop

APC PART I WORKSHOP

MAPPING AND CARTOGRAPHY

Denise Yeung

6 May 2017

MAPPING

The act or process of making a map.

A matching process where the points of one set are matched against the pointsof another set.

Graphical representation of a procedure, process, structure, or system thatdepicts arrangement of and relationships among its different components, andtraces flows of energy, goods, information, materials, money, personnel, etc

(Mathematics) a mathematical relation such that each element of a given set(the domain of the function) is associated with an element of another set (therange of the function)

MAPPING IN CARTOGRAPHY

Mapping is the mental interpretation of the world(Dorling and Fairbairn, 1997 Mapping: Ways ofRepresenting the World)

i.e. how we perceive the world around us and interpretit spatially, often into a mapped form.

EXAMPLES OF

CONTEMPORARY MAP:

- Topographic Map- Thematic Map- 3D Map - 3D Flythrough Animation- Interactive Map- Augmented Map- Satellite Image Map- Community Arts Map- MTR Route Map ?- Photomontage ?- ….

MAP

Static, dynamic, interactive cartographic output.

Map is a vehicle that may transfer your ideas about a place into the mind of amap reader.

Map is graphic representations of the cultural and physical environment.

Map is a symbolic depiction highlighting relationships between elements ofsome space, such as objects, regions, and themes. (wiki)

A map is a symbolised representation of geographical reality, representingselected features or characteristics, resulting from the creative effort of itsauthor’s execution of choices, and is designed for use when spatialrelationships are of primary relevance. (ICA)

CARTOGRAPHY

Cartography is the Art, Science and Technology of map making. (GeneralDefinition)

Cartography is the discipline dealing with the art, science and technologyof making and using maps. (ICA)

A holistic representation and intellectual abstraction of geographicalreality, intended to be communicated for a purpose or purposes,transferring relevant geographical data into an end product which isvisual, digital or tactile. (ICA)

MAP AND PLAN

Plan is generally produced at large scale for technical purposes, suchas architecture, engineering, planning and so on, so as to accurately

and unambiguously capture all the geometric features of a site,building, etc.

Map is drawn in small scale from which cartographic enhancementand generalization is significantly applied. Map is used commonly todepict geographic entities.

MAP AND PLAN OF HONG KONG

(LANDSD)

HP1C 1: 1 000 2 m

HP5C 1: 5 000 10 m

HM20C 1: 20 000 20 m

HM50CL 1: 50 000 50 m

HM100CL 1:100 000 100 m

HM200CL 1:200 000 100 m

MAP AS A TECHNICAL DEVICE

Communication Model

• Toward Functional Map

• Optimal Map (is it effective?)

Cartography as graphic communication

MAP TYPES

by function (conventional paper map)

• Topographic

• Thematic

TOPOGRAPHIC MAP

• General purpose map - customarily display natural and man-made objectsfrom geographical environment, emphasizing on location.

• General characteristics –• most widely used with wide range of information;

• designed to support other map based on the essential physical and culturalcomponents of a place and their relationships;

• contour lines to depict the shape and elevation of land, rendering the three-dimensional ups and downs of the terrain;

• natural features to show and name works of nature including mountains,valley, plains, lakes, rivers and vegetation;

• manmade features to identify principal works of man such as roads,boundaries, transmission line and major buildings

THEMATIC MAP

• Designed to demonstrate particular features or concepts - Thus, inconventional use, this term excludes topographic maps. The basemaps of most thematic maps, however, contain topographic elements.

• Every thematic map is composed of two important components: thegeographic base map and the thematic overlay.

CARTOGRAPHIC PROCESSES

Map Purpose

Map Projection

Map scale(s) (media of delivery)

Data processing (Geospatial Data Analysis)

• Collection and selection• Manipulation

Information Delivery (Visual Variables, Perception Prop.)

• Cartographic presentation / design / visualization• Dissemination

….….

THE EARTH AND MAP

Map Projection• any systematic way of

presenting the meridians and parallels of the earth on a plane surface

• each point on the plane surface corresponds to the one point of the earth

COORDINATE SYSTEMS OF HK

Geographic Coordinate System• based on WGS84 datum • coordinate reference in latitude and longitude value

Universal Transverse Mercator Coordinate System• based on WGS84 datum • UTM Projection• coordinate reference in metre unit (mN, mE)

Plane Rectangular Coordinate System• known as Hong Kong 1980 Grid• based on HK 80 datum• Transverse Mercator Projection• false origin coordinate : 800 000 mN, 800 000 mE

DIRECTION ON EARTH

Grid north

• the direction in which the grid line points towards the top of themap

True north

• the direction of the North Pole from the observer, coincident withthe meridian through that point. All meridians are true north linesbecause they pass through the North Pole

Magnetic north• the direction in which the compass needle points

RELATIONSHIPS AMONG DIFFERENT

TYPES OF NORTH

Angle of grid convergence• the angle between true north and grid north

Magnetic declination• the angle between magnetic north and true north

Magnetic variation• the annual change or movement of magnetic field expressed in seconds

east or west of magnetic north

North Pole

North Grid linesTrue North lines

Convergence at sheet centre 11”E

Magnetic declination 1973 1°10’ W

Annual change 1’ E

TN

MN GN

1°10’ 11”

Example of True, Mangeticand Grid North Diagram

RELATIONSHIPS AMONG DIFFERENT

TYPES OF NORTH

MAP SCALE

Presentations of scale• Representative Fraction (R.F.)

• distance on map/ distance on ground• Written statement• Graphic form

“larger scale” vs “smaller scale” • one map has a ‘larger scale’ than another if a given distance on the

ground is represented by a greater map distance than on the other map

CARTOGRAPHIC VISUALISATION

PROCESS

Visualisation Process

Translation of spatial data by applying cartographic methods and techniques.

COMMUNICATION OF GEOSPATIAL

INFORMATION

“How do I say what to whom, and is it effective?”

Communication Model -> Optimal Map

HOW DO I SAY WHAT TO WHOM?

In cartography saying is effectuated by using graphic symbols

What = the information to be transferred to the map userWhom = specific map user(s)How = by using the grammatical rules of the language ofcartographic symbols (semiology)

Cartographer processes data in a scientific manner and present /deliver information appropriately with proper aesthetic qualityand right perception to user.

STEPS IN CARTOGRAPHIC DESIGN

Choice of representation method (type of map)

Translation:geospatial data characteristics => choice of visual variables

Geospatial data analysis

cartographic grammar

(thematic/topographic) mapping

GEOSPATIAL DATA ANALYSIS

1. Can the data be classified / grouped?

• useful for symbol design decisions

2. What are the dimensions of the features?• point, line, area, volume ? • choice of corresponding symbols

3. What is the measurement level?• nominal, ordinal, interval, ratio

Residential

High Density

Medium Density

Low Density

Agricultural

Recreational

No Restriction

Subject to Restrictions

Urban Park

Countryside

1. CATEGORIZE / CLASSIFY


1. Can the data be classified / grouped?• useful for symbol design decisions

2. What are the dimensions of the features?

• point, line, area, volume ?

• choice of corresponding symbols

3. What is the measurement level?• nominal, ordinal, interval, ratio

2. DIMENSIONS OF FEATURES (OBJECTS)

Influence of scale !

area symbol

point symbol

linesymbol

SYMBOLS’ INHERENT CHARACTERISTICS

• area symbols have pattern and colour

• line symbols have weight(thickness), pattern and colour

• point symbols have form, weight, pattern and colour

PICTORIAL

POINT SYMBOLS

GEOMETRICAL

POINT SYMBOLS

LETTER- AND

NUMBER

SYMBOLS

SYMBOL DESIGN & VISUAL VARIABLES

▪ Cartographic symbols can be varied in many ways, e.g. pictorial, geometric and alpha numerical.

▪ However, there are a number of basic variations or visual (or graphic) variables (Bertin, 1967)

Bertin’s Six Visual Variables

/ texture

/ form

COLOUR REFERS TO THE HUE OF A SYMBOL

POINT SYMBOLS

LINE SYMBOLS

AREA SYMBOLS

saturationvalue

Most powerful, frequently used !(mis)

VISUAL VARIABLE - COLOUR

VALUE REFERS TO THE RELATIVE LIGHTNESS OR

DARKNESS OF A SYMBOL (BLACK:WHITE RATIO)

POINT SYMBOLS

LINE SYMBOLS

AREA SYMBOLS

VISUAL VARIABLE - VALUE

VISUAL VARIABLE - FORM

Form refers to the shape of a symbol

Point

Line

Area

refer to the form of the graphical components

VISUAL VARIABLE - FORM

Form refers to the shape of a symbol

They do not differ in ‘form’ but in position only !

APPLICATION OF VISUAL VARIABLE

VISUAL VARIABLE & PERCEPTION

PROPERTIES

Visual variables have one or more of the following perception properties:

- associative- selective- ordered- quantitative

PERCEPTION PROPERTIES

1. Associative : symbols look of equal importance.

2. Selective : groups of symbols can easily be distinguished.

3. Ordered : order between symbols can be distinguished.

4. Quantitative : order in terms of amounts can be distinguished.

VISUAL VARIABLES & ASSOCIATIVE

PERCEPTION

?

✓ ✓

✓

SELECTIVE PERCEPTION ?

VISUAL VARIABLES & SELECTIVE

PERCEPTION

? ✓

✓✓✓✓

MAXIMUM NUMBER OF CLASSES

TO ENABLE SELECTIVE PERCEPTION

Point symbols Line symbols Area symbols

Visual variables

Size4 4 5

Value 3 4 5

Texture 2 4 5

Colour 7 7 8

Orientation 4 2

VISUAL VARIABLES & ORDERED

PERCEPTION

?

✓

✓✓

VISUAL VARIABLES & QUANTITATIVE

PERCEPTION

✓✓

Perception propertiesVisual

variablesAssociative Selective Ordered Quantitative

Position + - - -

Form + - - -

Orientation + o - -

Colour + ++ - -

Texture o + o -

Value - + ++ -

Size - + + ++

PERCEPTION PROPERTIES OF VISUAL

VARIABLES


1. Can the data be classified / grouped?• useful for symbol design decisions

2. What are the dimensions of the features?• point, line, area, volume ? • choice of corresponding symbols

3. What is the measurement level?

• nominal, ordinal, interval, ratio

MEASUREMENT LEVELS OF GEOGRAPHIC

INFORMATION

▪ NOMINAL

▪ ORDINAL

▪ INTERVAL

▪ RATIO

▪ NOMINAL (Qualitative)• data of different nature/identity of things, • no ranking,• no arithmetic manipulations,• labelling qualitative differences only.• e.g. soil types, gender, language.

▪ ORDINAL

▪ INTERVAL

▪ RATIO


INFORMATION

▪ NOMINAL

▪ ORDINAL (between Qualitative & Quantitative)

• with hierarchies, • not quantitatively determined, • exact differences in amounts cannot be expressed,• no arithmetic manipulations.• e.g. road classes. ‘warm’ versus ‘cool’.

▪ INTERVAL

▪ RATIO


INFORMATION

▪ NOMINAL

▪ ORDINAL

▪ INTERVAL (Quantitative)

• labelling, ranking and differences in amounts;• impossible to work out relationships/ratios between

measurements;• with arbitrary zero.• e.g. temperature (freezing point at 0oC).

▪ RATIO


INFORMATION

▪ NOMINAL

▪ ORDINAL

▪ INTERVAL

▪ RATIO (Quantitative)

• labelling, ranking and differences in amounts,• absolute zero point.• e.g. population.

• absolute ratio – result of direct measurements, e.g. population;• relative ratio – derived data, e.g. population density.


INFORMATION

CARTOGRAPHIC GRAMMAR

Informationvisual variables

Perception Property

Abs. R

Rel. R

Interval

Ordinal

Nominal

Quantitative

Association

Ordered

Ordered

(+/- Selection)

Ordered

CARTOGRAPHIC GRAMMAR

Perception propertiesVisual

variablesAssociative Selective Ordered Quantitative

Position + - - -

Form + - - -

Orientation + o - -

Colour + ++ - -

Texture o + o -

Value - + ++ -

Size - + + ++

Nominal

Ordinal / Interval / Rel. ratio Abs. ratio

COLOUR

Characteristics of colour

• Hue: associate with differences in wavelength, e.g. red, green, blue

• Value: sensation of lightness or darkness as rated on a gray scale

• Intensity/chroma: richness and saturation of colour

COLOUR

3 additive primaries• red, green, blue

3 subtractive primaries• cyan, magenta, yellow

4 process colours• cyan, magenta, yellow and black

Spot colour• e.g. brown for contour lines

SHAPE OF THE GROUND

Relief• a general term applied to the shape of the ground

in a vertical plane.

• a relief on a map is represented by means of heights and shape of the ground, above or below a datum which is normally sea level.

RELIEF REPRESENTATION

Two Methods

i. Representation of Height

ii. Representation of Shape


Representation of Height• Bench Mark• Trigonometrical Heights• Spot Heights• Contour Lines• Form Lines

Representation of Shape- Hachures- Relief Ornamentation- Layering (Elevation Tints or Hypsometric Colouring)- Hill Shading


TYPOGRAPHY

Typographic Design• Type style: the design character of the type

• Type form: capital letters, lowercase letters, small capitals, roman, italic, slant, upright

• Type size: refers to the letter height, 1 point (1/72 in.) nearly equal to 0.35mm

• Type colour

Basic considerations regarding the choice of any particular typestyle:

• legibility• sufficient size, e,g 1mm in height is at the edge of visual

discrimination• perceptibility

• heavy tones or dark colours the weight of the lettering shouldstands out against any background interference such as

• suitable for reproduction• styles chosen do not render poorly when reduced

• harmony• different typefaces used on a map should all be in harmony, not

only with each other but also with other map features• Versatility

• within one family of typefaces there should exist a sufficient range ofpossible choices

TYPOGRAPHY

SERIF & SANS SERIF

serif

A small decorative line added as embellishment to the basic form of a character. Typefaces are often described as being serif or sans serif (without serifs). The most common serif typeface is Times Roman. A common sans serif typeface is Helvetica.

http://www.webopedia.com/TERM/C/character.html

http://www.webopedia.com/TERM/S/sans_serif.html

http://www.webopedia.com/TERM/T/typeface.html

OUTPUT

Visualize, Digital, TactilePrint-on-demand vs Bulk PrintingPaper material

• Volume: ream/roll • Weight: gram per square metre• Size: e.g. International 'A' sizes• characteristics (quality & printability)

• dimensions stability• opacity• grain direction• Strength, receptive to ink• Smoothness

WHAT IS GENERALIZATION?

The process of reducing the amountof detail in a map (or database) in a

meaningful way

One of the main challenges to generate derived products from asingle very detailed database is to have appropriate generalizationtechniques that address both database as well as cartographicaspects. …The issue of generalization of framework data focusing onboth geometric (cartographic) generalization and conceptual(database) generalization ….

66

WHY IS GENERALISATION

NECESSARY?

If a map is produced from a database at a scale smaller than intended, the map might become illegible.

Increased density of the map contents due to scale reduction.

Features become too small to be seen clearly, or to be represented at true size (to scale) on a monitor or on paper.

The data requires Generalisation.

67

WHY IS GENERALISATION NECESSARY?

Challenge:

How to make the best use of map space to optimizelegibility at a given scale for a particular purpose of the map.

68

GENERALISATION

Generalization related to the map purpose

Generalisation is scale related

Generalization is partly subjective

Generalization is output related

69

WHERE DOES GENERALISATION

REALLY BEGIN?

Scales ≥ 1:5,000

the planimetric accuracy of the original survey data are fairly wellmaintained.

Scales 1:10,000 – 1:20,000:

some roads and other features (e.g. railways) are no longer true to scale.Some simplification, enlargement or displacement of features.

70

Scales 1:20,000 – 1:50,000

roads and buildings are no longer true to scale. Buildings are oftensimplified and displaced. In densely built-up areas buildings are alreadyomitted or combined.

Scales ≤ 1:50,000:

- Selection, reclassification and resymbolization;

- Strong simplification and displacements;

- Buildings no longer true to scale or not shown as individual buildings(except distinct ones as landmarks);

- Merging of area features.

71

WHERE DOES GENERALISATION

REALLY BEGIN?

CONCEPTUAL AND GRAPHIC

GENERALIZATION

Conceptual generalization: • selection/omission of categories, (re)classification, (re)symbolization

or the enhancement of objects.

• It mainly effects the semantics (attributes) of the data. The maplegend changes. The symbology in the map may change.

Graphic generalization:• simplification, enlargement, displacement, or (merging) the graphic

combination or selection of objects.

• It mainly effects the geometry and location of the objects. None of theprocesses affects the symbology.

73

74

- Assign symbols to the object geometry, e.g. thicker road casing

Conceptual generalization

Enhancement (emphasis)

Selection (omission) of categories- extraction of purpose and scale adapted objects or group of objects based on database attributes.

Classification - reclassify objects into another category to enable aggregation with objects having the same class

Symbolization - geometry type change (includes collapses a polygon either to a line or to a point)

75

Simplification

Enlargement (enlarge objects)

Displacement (displace objects in conflict situations)

Merging (combine objects of same of similar class)

Selection (omission)

Graphic generalization

SEQUENCE OF GENERALIZATION ACTIVITIES

Conceptual

Conceptual selection: extraction of purpose and scale adapted objects or group of objects based on database attributes.

Reclassification: reclassify objects into another category to enable aggregation with objects having the same class.

Resymbolization: geometry type change (includes collapses a polygon either to a line or to a point)

Assign symbols to the object geometry

76

Graphic

Aggregation: combine objects of the same or a similar class

Exaggeration: enlarge objects

Displacement: displace objects in conflict situations

Deletion: removes objects

Simplification: form of the lines and area outlines

Name placement: optimize the placement of names

77

SEQUENCE OF GENERALZSATION ACTIVITIES

INTERRELATION OF GENERALIZATION

ACTIVITIES

You can subdivide generalization into a several sets of processes.However the processes usually interrelate. One process is often requiredas a result of another process.

For example:

Houses along a road need to be displaced when a road has tobe enlarged in order to remain visible after scale reduction

78

GUIDELINES FOR MAP GENERALIZATION

Select those features that are necessary or useful for the purpose of themap and in accordance to the scale. Emphasize the most importantfeatures and omit or repress the less important ones;

Have regard for the displacement priority rules;

Have regard for the minimum sizes of graphic map symbols;

Within the limitations imposed by the map scale, planimetricaccuracy/shape should be maintained.

79

Priority rules for the displacement• Trigonometric points• Hydrography features• Railways• Roads• Buildings• Area features, e.g. woodland

80


retain important and noticeable features, e.g. isolated buildings in arural area will often be retained on medium scale;

within the limitations imposed by the map scale, shape of features andthe character of the area should be maintained;

Relationships between features should be taken into account, e.g. thecontours should still fit to the river system.

Be consistent, apply same rule for the same feature in a map series.

81


Good Luck

Documents

APC Part I Workshop