The Map as a Model of Geographic Data The Language of Spatial Thinking Fundamentals of GIS Michael N. DEMERS Assoc.Prof.Dr. Necla ULUGTEKIN ulugtek@itu.edu.tr

Spatial thinking requires us to be able to select observe measure catalogue characterise what we encounter.

Data are collected in the field  basic (absolute) data remote sensing  basic (absolute) data existing maps  derived data catalogues  derived data ...

Scanning

The Digitizing Tablet

Existing maps into the GIS Different level of generalisation Different level of scales Different projections Different symbolisation Before GIS project we will be able to identify potential problems for editing such problems. Now, we will learn how spatial features and their relationships can be shown in a form (which is map) that allows us to view these relationships more easily and, therefore how we can begin to formulate methods of analysis.

Cartography is the art, science and technology of making maps together with their study as scientific documents and works of art. (1973, ICA)

Cartography is the organisation, presentation, communication and utilisation of geo-information in graphic, digital or tactile form. (ICA, 1991) It can include all stages from data presentation to end use in the creation of maps and related spatial information products. A knowledge about cartographic methods will increase a portion of our spatial vocabulary that we have called graphicacy.

Map an abstraction of reality, it is not reality itself. the fundamental language of geography. symbolise image of geographical reality representing selected feature representing feature relationships representing characteristics Spatial data abstraction All these symbolised images: it could not possible be drawn of such a small peace of paper.

Maps can be used Navigation Exploration Discovery Interactive computer navigation Education Forecasting …

Primary Types of Maps Topographic Map (General Reference) Thematic Map Reference Maps are used as input to a GIS and then thematic information can be added.

GIS works together geology surveying soil science other disciplines...

GIS is used in these disciplines, in addition to Geological maps Topographic maps Cadastral Maps Soil Maps

The thematic context of GIS includes Vegetation maps Transportation maps Animal distribution maps Utility maps Urban plans Zoning maps ... land use maps land cover remotely sensed images urbanisation air pollution animated maps temporal maps

GIS is hardware software people (organisation) data

GIS is about data integration spatial analysis link with application based models

The traditional approach to mapping called the communication paradigm The map was a final product designed to communicate a spatial pattern through the use of symbols, class limit selection and so on. The traditional method was limited because raw, pre-classified data are not readily available to the map user

Communication Paradigm Real World Cartographer Conception Map Map User Conceptions In other words, the users have only final product, is incapable of regrouping the data into forms more useful for changing circumstances and needs.

The alternative approach to cartography which is computer technology called the analytical or holistic paradigm Maintains the raw attribute data inside a computer storage device and display data based on user needs and user classifications The use of computer technology for map making should allow for both communication and analysis.

Map Scale Scale is the ratio of distance on the map to the same distance as appears on the earth Methods of illustrating map scale verbal scale 1mm = 1000 mm representation fraction 1:1000 graphic or bar scale 1:1000  1:5000  1:10 000  1:25 000 It is always better to reduce a map after analysis than to enlarge it for analysis.

Generalisation Every map is, in principle, generalised. Why? increasing density of the map contents due to scale reduction limit of sharpness of the eye, printing capabilities minimum size of symbols on map the choice of degree of generalisation depends on aim and scale of the map. Omitting (elimination) selection simplification (smoothing) repressing and exaggerating emphasising displaying

1 : 5 000 1:25 000 1:50 000

Map Characteristics Maps as images of the world, represent the locations of objects, as well as their qualities or magnitudes. Objects are represented as points, line, areas or surfaces in the computer memory as like in the reality.

Objects Parcel area (value) Parcel owner (text) photo

Levels of data measurements qualitative or nominal level ordered or ordinal level quantitative or interval level Information about different nature / identity of things. E.g. forest house. Information with a clear element of order, not quantitatively determined. Hamlet, village, town, city, conurbation. Information about specified amounts, e.g. number of inhabitants, employees, students.

GRID SYSTEMS for MAPPING Geographical Coordinates based on latitude and longitude for the locating of objects or features on the spherical (elipsoidal) earth or its reference globe. Rectangular Coordinates or Plane Coordinates allows us to locate objects correctly on these flat maps.

elevation Sea level

Geographical Coordinates meridian Prime meridian Parallel Equator Prime meridian

Map Projection The three-dimensional geographic relationships of the Earth surface must be transformed to the two-dimensional plane of the map by any of several procedures called map projections. Division of map projections according to their properties conform projections equivalent (Equal-Area) projections equidistant projection others Angles measured on the earth equal to those on the map. Equality of surface area. Preserve areas Distances measured on meridian from one point to other point are correct or scale factor equal to 1. The distance measurements from any other point on the map will be inaccurate.

cylindrical projections conic projections azimuthal projections Division of map projections according to their construction cylindrical projections conic projections azimuthal projections Division of map projections according to their aspect Polar (regular) Equatorial (transversal) oblique The selection of map projection is fundamental process of designing a GIS

Projection surfaces a tangent conic (cylindirical or azimuthal) projection with one standard parallel Perspective projection ! Pseudo Projections

a secant conic projection with two standard parallels

Position of the (earth) rotation axis to surface normal polar or regular I equatorial or transverse ___ oblique /

preserve the property of local shape conformed projections

Perspective projection !

preserves distances but only along one or a few lines equidistant projections the azimuthal equidistant projections

preserve the property of area equal area or equivalent projections

miscellaneous projections (pseudo ! )

Robinson Projection

Winkel Tripel Projeksiyonu

MARS 2001 Winkel Tripel Projeksiyonu

Arabian Island & Greenland a: original b: equal area projection c: conform projection

UTM (Universal Transverse Mercator) C.S. North northern hemisphere Central meridian for zone 500 000m E Equator (0m N, 10 000 000m S) southern hemisphere South . 1800W-1800E (60of longitude wide- 60 gores (zone)) 800S - 840N (80of latitude wide - 20 latitudinal belts) ? Prime meridian

UNIVERSAL TRANSVERSE MERCATOR PROJECTION (UTM) cylindrical, equatorial, conform projection the area is covered by 80° South - 84° North latitude the earth is divided into 60 zones (each 6° longitude) 180° West Longitude - 0° - 180° East Longitude 20 latitudinal belts (each 8° latitude) scale factor = 0.9996 origin shifted 500 000 m to east (false easting) origin shifted 10 000 000 m to south for the southern hemisphere the Hayford ellipsoid, the ED50 datum For polar regions we use a Universal Polar Stereographic (UPS) grid or projection.

The Cartographic Process data collection (first step of GIS) data compilation (classification and symbolism) map production map reproduction (output of GIS) data collection (first step of GIS) data compilation (classification and symbolism)development of base map map production map reproduction quantity of reproduction quality of reproduction color (photo-offset)

Map symbolism According to their dimensional characteristics point symbol (location and identity) line symbol (linear characteristics) area symbol (provinces, countries, soil units)

Map symbolism According to their shape cartographic symbol grouped in three main categories pictorial or descriptive symbols geometric or abstract symbols letter or number symbols other symbols (pie graph, bar graph etc.)

Symbols visual variables shape size boyut orientation value texture color value

Color for map design hue intensity/value saturation

dot map is a proportional changing in data Thematic Maps dot map is a proportional changing in data choropleth map (value-by-area mapping) statistical mapping class interval selection equal class or constant interval methods variable intervals - arithmetic, logarithmic, other mathematical series, unsystematic … (contour line on a topographic map class interval selection for choropleth maps.)

Electronic Atlas Project ITU-1185

The Nature of Spatial Data model construction and geographic object selection (surveying, photogrammetry, remote sensing, recycling old maps, statistical surveys) select and construct cartographic representation (road map, topographic map, ...) medium output (paper map or on-screen map) Cartographic database are collected from existing map rather than from field work or remotely sensed data , and they transferred to the computerised database. Geographic database is collected from a survey instrument. The nature of spatial data: from reality, via model construction and selection to a digital landscape model, followed by selection and construction to a cartographic representation towards a digital cartographic model, presented as a map, which result in the user’s mental map.

reality digital landscape model digital cartographic model map reality digital landscape model digital cartographic model map mental map (reality????)

What we learnt new perspective (map, scale, communication, ...) new concepts (cartography, generalisation, projection, ...) and What we know? “new people” ...