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GIS IS NOT CARTOGRAPHY. CARTOGRAPHIC BASICS. Maps perform two important functions: Storage medium for information that humanity needs Provides a picture of the world to help understand spatial patterns, relationships, and environmental complexity Maps tell us:

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Presentation Transcript
slide1

GIS

IS

NOT

CARTOGRAPHY

cartographic basics
CARTOGRAPHIC BASICS
  • Maps perform two important functions:
  • Storage medium for information that humanity needs
  • Provides a picture of the world to help understand spatial

patterns, relationships, and environmental complexity

Maps tell us:

  • Where is it?
  • What is it?
  • (often) When is it?
  • What is nearby? How far away? In which direction? How

do I get there?

  • What other things are there also?
  • How might they be related?
slide3

CARTOGRAPHIC BASICS

Where am I? After James R. Smith, page 46

How far to my destination?

In what direction do I go?

How large?

What shape?

slide4

CARTOGRAPHIC BASICS

  • All maps have the same goal:
  • Communicating spatial relationships
  • Communicating the ‘form’ of the landscape

Basic characteristics of all maps:

  • Location
  • Attribution
  • Reduction of reality
  • Scale
  • Geometrical transformation/projection
  • Abstractions of reality
  • Symbolism
cartographic basics5
CARTOGRAPHIC BASICS
  • Location and Attribution allow many types of relationships
  • to be formed:
  • Relationships among locations with no attributes –

distance, bearing

  • Relationship among various attributes at the same point
  • Relationship among different locations of the same attribute
  • Relationships among locations of combined/derived

attributes of given distributions -- spatial distribution

of per capita income vs. educational attainment

slide6

CARTOGRAPHIC BASICS

  • Classification of maps:
  • Classed by Scale

Small scale

Medium scale

Large scale

  • Classed by Function

General reference maps

Thematic/special purpose maps

Charts

  • Classed by Subject Matter

Cadastral maps

Plans

Soil, vegetation, precipitation, etc.

The principal task of cartography is to communicate

environmental information. The task of the map designer is to enhance the map user\'s ability to retrieve information.

slide7

CARTOGRAPHIC BASICS

  • Mapping involves information transformations:
  • Data collection
  • Selection
  • Classification
  • Simplification
  • Exaggeration
  • Symbolization
  • Use of map

The cartographer\'s task - explore the ramifications of each

mapping possibility and choose the most appropriate for the

intended task. Who is your audience?

slide8

CARTOGRAPHIC BASICS

Four main cartographic processes:

  • Collecting and selecting data for mapping
  • Manipulating and generalizing the data, designing and

constructing the map

  • Reading or viewing the map
  • Interpreting the information presented on the map

Skilled cartographers must be familiar with all mapping activities, including geodesy, surveying, photogrammetry, remote sensing, GIS.

Skilled cartographers must be familiar with the principals of human thought and communication.

Skilled cartographers must be familiar with the disciplines associated with the environmental features being mapped.

slide9

HISTORY OF CARTOGRAPHY

  • Changing ideas about cartography:
  • Earliest maps are figurative, ceremonial, artistic
  • 100 A.D. – the Greeks develop concepts of geometry
  • 1200 A.D. - \'church maps\' of the Dark Ages
  • 1300 A.D. - Renaissance brings major expansion of world

knowledge, travel

  • 1680 AD – the Enlightenment – concept of \'Western science\'

and concern with positional accuracy

  • 1800s – place => space; concept of distribution; thematic maps

come into being; environmental data becomes important

  • 1950+ - systems approach to the environment => reintegration

of themes and concept of cartographic modeling

slide10

HISTORY OF CARTOGRAPHY

100 A.D. – geometry

1200 – Dark Ages

1300 – Renaissance

1680 – Enlightenment

1800s – Place => Space

1950+ -- Systems Approach

From Robinson, Sixth Edition, page 22

slide11

HISTORY OF CARTOGRAPHY

Constant goal:

Society demands maps that are timely, accurate and complete. There has been a continual demand for greater accessibility to lower cost maps. Cartographers\' constant struggle with these demands leads to evolution of maps

Changing technology:

  • Manual techniques are still used today
  • 12th century – magnetic compass
  • 16th century – mechanical printing press
  • 17th century – optical technology
  • 19th century – photo-chemical technology
  • 1950 – electronic/computer technology

The success of computer-assisted mapping rests on the skill of the cartographer and development/ application of computer system components within a cartographic environment.

slide12

HISTORY OF CARTOGRAPHY

Magnetic Compass

Mechanical Printing Press

Lens Grinding, Telescope Lenses, Lasers

Photography, Lithography

Computer Technology

slide13

BASIC GEODESY

“Geodesy is the science that determines the figure of the

earth and the interrelation of selected points on its surface

by either direct or indirect techniques.”

“Mapping involves determining the geographic locations

of features on the earth, transforming these locations into

positions on a flat map through the use of map projection,

and graphically symbolizing these features.”

“Cursed be he who moves his neighbor’s boundary stone.”

slide14

BASIC GEODESY

  • The earth is not round:
  • Authalic sphere – a sphere with the same surface area as

the ellipsoid – used as base figure for mapping.

  • WGS 72 and 84 ellipsoids based on satellite orbital data
  • Clarke 1866 ellipsoid used for mapping in North America

(based on ground measurements made in Europe, India,

Peru, Russia, South Africa)

  • Geoid is a more faithful figure of the earth – 3D shape

approximated by mean sea level in the oceans and the

surface of a series of sea-level canals crisscrossing the

continents.

slide15

BASIC GEODESY

Cartographic use of sphere, ellipsoid, geoid:

  • Authalic sphere used for small scale maps of countries,

continents, larger areas

  • Ellipsoid used for large scale maps such as topographic

maps and nautical charts; GPS systems use ellipsoid

  • Geoid used as reference surface for ground surveyed

horizontal and vertical positions; elevations determined

relative to mean sea level geoid

slide16

BASIC GEODESY

From James R. Smith, page 34

slide17

BASIC GEODESY

After James R. Smith, page 52

slide18

BASIC GEODESY

  • Direction on the earth:
  • Geographic/true directions determined by the orientation of

the graticule on the earths\' surface

  • Magnetic directions must take into account the compass

variation/magnetic declination

  • True azimuth – clockwise angle a great circle makes with the

meridan at point of origin (changes constantly along the arc)

great circles = shortest distance between points

  • Constant azimuth – line which makes a fixed angle with all

meridians (rhumb line or loxodrome); spirals to pole

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