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:

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?

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?

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 BASICS

Location and Attribution allow many types of relationshipsto 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

CARTOGRAPHIC BASICS

Classification of maps:

Classed by ScaleSmall scaleMedium scaleLarge scale

Classed by FunctionGeneral reference mapsThematic/special purpose mapsCharts

Classed by Subject MatterCadastral mapsPlansSoil, 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.

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?

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.

CARTOGRAPHIC BASICS

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

HISTORY OF CARTOGRAPHY

From Robinson, Sixth Edition, page 22

100 A.D. – geometry1200 – Dark Ages1300 – Renaissance1680 – Enlightenment1800s – Place => Space1950+ -- Systems Approach

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.

HISTORY OF CARTOGRAPHY

Magnetic Compass

Mechanical Printing PressLens Grinding, Telescope Lenses, Lasers

Photography, Lithography

Computer Technology

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.”

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.

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

BASIC GEODESY

From James R. Smith, page 34

After James R. Smith, page 52

BASIC GEODESY

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