APC PART I WORKSHOP MAPPING AND CARTOGRAPHY

Transcription

1 APC PART I WORKSHOP MAPPING AND CARTOGRAPHY 5 June 2015

2 MAPPING The act or process of making a map. A matching process where the points of one set are matched against the points of another set. Graphical representation of a procedure, process, structure, or system that depicts arrangement of and relationships among its different components, and traces 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 (the range of the function)

3 MAPPING IN CARTOGRAPHY Mapping is the mental interpretation of the world (Dorling and Fairbairn, 1997 Mapping: Ways of Representing the World) i.e. how we perceive the world around us and interpret it spatially, often into a mapped form.

4 MAP Static, dynamic, interactive cartographic output. Map is a vehicle that may transfer your ideas about a place into the mind of a map reader. Map is graphic representations of the cultural and physical environment. Map is a symbolic depiction highlighting relationships between elements of some space, such as objects, regions, and themes. (wiki) A map is a symbolised representation of geographical reality, representing selected features or characteristics, resulting from the creative effort of its author s execution of choices, and is designed for use when spatial relationships are of primary relevance. (ICA)

5 CARTOGRAPHY Cartography is the Art, Science and Technology of map making. (General Definition) Cartography is the discipline dealing with the art, science and technology of making and using maps. (ICA) A holistic representation and intellectual abstraction of geographical reality, intended to be communicated for a purpose or purposes, transferring relevant geographical data into an end product which is visual, digital or tactile. (ICA)

6 MAP AND PLAN Plan is generally produced at large scale for technical purposes, such as 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 enhancement and generalization is significantly applied. Map is used commonly to depict geographic entities.

7 MAPS OF HONG KONG (LANDSD) HP1C 1: m HP5C 1: m HM20C 1: m HM50CL 1: m HM100CL 1: m HM200CL 1: m

8 MAP TYPES Communication model by function (geospatial) - Topographic Thematic

9 TOPOGRAPHIC MAP General purpose map - customarily display natural and man-made objects from 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 cultural components of a place and their relationships; contour lines to depict the shape and elevation of land, rendering the threedimensional 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

10 THEMATIC MAP Designed to demonstrate particular features or concepts - Thus, in conventional use, this term excludes topographic maps. The base maps of most thematic maps, however, contain topographic elements. Every thematic map is composed of two important components: the geographic base map and the thematic overlay.

11 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

12 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

13 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 : mn, me

14 DIRECTION ON EARTH Grid north the direction in which the grid line points towards the top of the map True north the direction of the North Pole from the observer, coincident with the meridian through that point. All meridians are true north lines because they pass through the North Pole Magnetic north the direction in which the compass needle points

15 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

16 RELATIONSHIPS AMONG DIFFERENT TYPES OF NORTH True North lines North Pole North Grid lines Example of True, Mangetic and Grid North Diagram TN MN GN Convergence at sheet centre 11 E Magnetic declination W Annual change 1 E

17 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

18 CARTOGRAPHIC VISUALISATION PROCESS Visualisation Process Translation of spatial data by applying cartographic methods and techniques.

19 COMMUNICATION OF GEOSPATIAL INFORMATION How do I say what to whom, and is it effective?

20 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 user Whom = specific map user(s) How = by using the grammatical rules of the language of cartographic symbols (semiology)

21 STEPS IN CARTOGRAPHIC DESIGN Geospatial data analysis Translation: geospatial data characteristics => choice of visual variables cartographic grammar Choice of representation method (type of map) (thematic/topographic) mapping

22 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

23 1. CATEGORIZE / CLASSIFY Residential High Density Medium Density Low Density Agricultural Recreational No Restriction Subject to Restrictions Urban Park Countryside

24 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

25 2. DIMENSIONS OF FEATURES (OBJECTS) area symbol point symbol line symbol Influence of scale!

26 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

27 PICTORIAL POINT SYMBOLS

28 GEOMETRICAL POINT SYMBOLS

29 LETTER- AND NUMBER SYMBOLS

30 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)

31 Bertin s Six Visual Variables / texture / form

32 THE VISUAL VARIABLES Colour Form / Shape Value Orientation Size Texture

33 VISUAL VARIABLE - POSITION line symbols point symbols area symbols

34 VISUAL VARIABLE - FORM Form refers to the shape of a symbol Point Line Area

35 VISUAL VARIABLE - COLOUR Colour refers to the hue of a symbol point symbols line symbols area symbols

36 APPLICATION OF VISUAL VARIABLE

37 APPLICATION OF VISUAL VARIABLE Which one is more appropriate?

38 APPLICATION OF VISUAL VARIABLE

39 CARTOGRAPHIC GRAMMAR Colour Form Value Orientation Size Texture

40 VISUAL VARIABLE & PERCEPTION PROPERTIES Visual variables have one or more of the following perception properties: - associative - selective - ordered - quantitative

41 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.

42 PERCEPTION PROPERTIES ASSOCIATIVE?

43 ASSOCIATIVE PERCEPTION A visual variable is called associative if spontaneously all symbols to which that variable has been applied are seen as of equal importance. Such a group of symbols has a homogeneous appearance: no one symbol stands out above the others.

44 VISUAL VARIABLES & ASSOCIATIVE PERCEPTION?

45 ASSOCIATIVE PERCEPTION Position Form Orientation Colour Texture* are ASSOCIATIVE Value Size are DISASSOCIATIVE

46 SELECTIVE PERCEPTION A visual variable has selective perception properties if spontaneously all symbols differentiated by that variable can be arranged in distinct groups.

47 SELECTIVE PERCEPTION?

48 VISUAL VARIABLES & SELECTIVE PERCEPTION?

49 SELECTIVE PERCEPTION Value Size Colour Texture Orientation* are SELECTIVE Position Form are NOT SELECTIVE

50 MAXIMUM NUMBER OF CLASSES TO ENABLE SELECTIVE PERCEPTION Point symbols Line symbols Area symbols Visual variables Size Value Texture Colour Orientation 4 2

51 ORDERED PERCEPTION A visual variable has ordered perception properties if spontaneously all symbols differentiated by that variable can be placed in an unambiguous order / ranking. E.g. low - high least - most important

52 VISUAL VARIABLES & ORDERED PERCEPTION?

53 ORDERED PERCEPTION Value Size Texture* are ORDERED Orientation Colour Position Form are NOT ORDERED

54 QUANTITATIVE PERCEPTION A visual variable has quantitative perception properties if spontaneously all symbols differentiated by that variable may be separated from another by a distinct amount. a b c b = 4 x a c = 9 x a

55 VISUAL VARIABLES & QUANTITATIVE PERCEPTION

56 QUANTITATIVE PERCEPTION Only SIZE is a quantitative visual variable.

57 PERCEPTION PROPERTIES OF VISUAL VARIABLES Visual variables Perception properties Associative Selective Ordered Quantitative Position Form Orientation + o - - Colour Texture o + o - Value Size

58 MAPPABLE GEOGRAPHIC DATA Geographic data may be mapped if you can answer the following two questions: WHERE is it? WHAT is it? point, line or area measurement level

59 LOCATION & ATTRIBUTES

60 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

61 MEASUREMENT LEVELS OF GEOGRAPHIC INFORMATION NOMINAL ORDINAL INTERVAL RATIO

62 MEASUREMENT LEVELS OF GEOGRAPHIC INFORMATION 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

63 MEASUREMENT LEVELS OF GEOGRAPHIC 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

64 MEASUREMENT LEVELS OF GEOGRAPHIC 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 0 o C). RATIO

65 MEASUREMENT LEVELS OF GEOGRAPHIC 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.

66 CARTOGRAPHIC GRAMMAR Information visual variables Perception Property Abs. Q Rel. Q Quantitative Ordered Interval Ordered Ordinal Ordered Nominal Association (+/- Selection)

67 CARTOGRAPHIC GRAMMAR Nominal Visual variables Perception properties Associative Selective Ordered Quantitative Position Form Orientation + o - - Colour Texture o + o - Value Size Ordinal / Interval / Rel. ratio Abs. ratio

68 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

69 COLOUR

70 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

71 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.

72 RELIEF REPRESENTATION Two Methods i. Representation of Height ii. Representation of Shape

73 RELIEF REPRESENTATION Representation of Height Bench Mark Trigonometrical Heights Spot Heights Contour Lines Form Lines

74 RELIEF REPRESENTATION Representation of Shape - Hachures - Relief Ornamentation - Layering (Elevation Tints or Hypsometric Colouring) - Hilling Shading

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76 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

77 TYPOGRAPHY 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 should stands 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 of possible choices

78 OUTPUT Visualize, Digital, Tactile Print-on-demand vs Bulk Printing Paper 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

79 WHAT IS GENERALIZATION? The process of reducing the amount of detail in a map (or database) in a meaningful way One of the main challenges to generate derived products from a single very detailed database is to have appropriate generalization techniques that address both database as well as cartographic aspects. The issue of generalization of framework data focusing on both geometric (cartographic) generalization and conceptual (database) generalization. 79

80 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. 80

81 WHY IS GENERALISATION NECESSARY? Challenge: How to make the best use of map space to optimize legibility at a given scale for a particular purpose of the map. 81

82 GENERALISATION Generalization related to the map purpose Generalisation is scale related Generalization is partly subjective Generalization is output related 82

83 WHERE DOES GENERALISATION REALLY BEGIN? Scales 1:5,000 the planimetric accuracy of the original survey data are fairly well maintained. 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. 83

84 WHERE DOES GENERALISATION REALLY BEGIN? Scales 1:20,000 1:50,000 roads and buildings are no longer true to scale. Buildings are often simplified and displaced. In densely built-up areas buildings are already omitted 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. 84

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86 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 map legend changes. Graphic generalization: simplification, enlargement, displacement, or the graphic combination or selection of objects. It mainly effects the geometry and location of the objects. 86

87 Conceptual generalization CONCEPTUAL GENERALIZATION Thicker road casing 87

88 Graphic generalization GRAPHIC GENERALIZATION 88

89 SEQUENCE OF GENERALISATION 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 89

90 SEQUENCE OF GENERALISATION ACTIVITIES 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 90

91 INTERRELATION OF GENERALIZATION ACTIVITIES You can subdivide generalization into a several sets of processes. However the processes usually interrelate. One process is often required as a result of another process. For example: Houses along a road need to be displaced when a road has to be enlarged in order to remain visible after scale reduction 91

92 GUIDELINES FOR MAP GENERALIZATION Select those features that are necessary or useful for the purpose of the map and in accordance to the scale. Emphasize the most important features 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, planimetric accuracy/shape should be maintained. 92

93 GUIDELINES FOR MAP GENERALIZATION Priority rules for the displacement Trigonometric points Hydrography features Railways Roads Buildings Area features, e.g. woodland 93

94 GUIDELINES FOR MAP GENERALIZATION retain important and noticeable features, e.g. isolated buildings in a rural area will often be retained on medium scale; within the limitations imposed by the map scale, shape of features and the character of the area should be maintained; Relationships between features should be taken into account, e.g. the contours should still fit to the river system. Be consistent, apply same rule for the same feature in a map series. 94

95 Good Luck