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Introduction to

Geospatial Analysis

Dr. Emily A. Fogarty

SUNY Stony Brook

What is geography?

• The study of spatial variation

• How – and why – things differ from place to

place on the surface of the earth

• The study of how observable spatial

patterns evolved through time

Spatial variation: predominant religion

Why spatial variation exists: earthquakes

Changes over time: deforestation

What is geography?

• Geography is a spatial science

• Spatial behavior of people

• Spatial relationships between places

• Spatial processes that create or

maintain those behaviors and

relationships

Spatial behavior of people: population

Spatial relationships between places: trade

Spatial processes: commuting and

urban form

Five fundamental themes of geography

1) Location: the meaning of relative and

absolute position on the earth's surface

Sample terms: Latitude and longitude, site

and situation, direction, distance, scale

Skills: Map reading, identification

Questions: Where is ____? Where is ____

relative to where I am?

2) Place: the distinctive and distinguishing

physical and human characteristics of

locales

Sample terms: Physical and cultural

landscapes, sense of place

Skills: Description, compare and contrast

Questions: What does ____ look like?

Why? How is it different from ____?

Five fundamental themes of geography

3) Relationships within places: the

development and consequences of human-

environment relationships

Sample terms: Ecosystems, natural

resources, environmental pollution

Skills: Evaluation, analysis

Questions: What human-environment

relationships are occurring? How do they

affect the place and its inhabitants?

Five fundamental themes of geography

4) Movement: patterns and change in human

spatial interaction on the earth

Sample terms: Migration, diffusion,

globalization

Skills: Explanation, prediction

Questions: How has this spatial pattern

developed? Will it continue to change?

What does it mean for the places involved?

Five fundamental themes of geography

5) Regions: how they form and change

Sample terms: Formal vs. functional regions

Skills: Synthesis, application

Questions: How has this spatial pattern

developed? Will it continue to change?

What does it mean for the places involved?

Five fundamental themes of geography

http://en.wikipedia.org/wiki/Geography

Physical geography focuses on geography as an Earth science. It aims to understand the physical lithosphere,

hydrosphere, atmosphere, and global flora and fauna patterns (biosphere). Physical geography can be

divided into the following broad categories:

Human geography is a branch of geography that focuses on the study of patterns and processes that shape

human interaction with various environments. It encompasses human, political, cultural, social, and

economic aspects. While the major focus of human geography is not the physical landscape of the Earth

(see physical geography), it is hardly possible to discuss human geography without referring to the physical

landscape on which human activities are being played out, and environmental geography is emerging as a

link between the two. Human geography can be divided into many broad categories, such as:

http://en.wikipedia.org/wiki/Geography

Environmental geography is the branch of geography that describes the spatial

aspects of interactions between humans and the natural world. It requires an

understanding of the traditional aspects of physical and human geography, as

well as the ways in which human societies conceptualize the environment.

Environmental geography has emerged as a bridge between human and

physical geography as a result of the increasing specialization of the two sub-

fields.

Furthermore, as human relationship with the environment has changed as a

result of globalization and technological change a new approach was needed to

understand the changing and dynamic relationship.

Examples of areas of research in environmental geography include emergency

management, environmental management, sustainability, and political ecology.

Cartography studies the representation of the Earth's surface with abstract

symbols (map making). Although other sub-disciplines of geography rely

on maps for presenting their analysis, the actual making of maps is

abstract enough to be regarded separately.

Cartography has grown from a collection of drafting techniques into an

actual science.

A nautical chart of the Mediterranean Sea

from the second quarter of the 14th

century. It is the oldest original

cartographic artifact in the Library of

Congress. http://en.wikipedia.org/wiki/Cartography

Introduction to maps

What is a map?

• A generalized view of an area, usually some

portion of Earth’s surface, as seen from

above at a greatly reduced size

• Any geographical image of the environment

• A two-dimensional representation of the

spatial distribution of selected phenomena

Why make maps?

• To represent a larger area than we can see

• To show a phenomenon or process we can’t

see with our eyes

• To present information concisely

• To show spatial relationships

Represent a larger area

Show

what

we

can’t

see

Present info concisely

Show spatial

relationships

How do we read maps?

• Maps are selective views of reality

• Size of the map relative to reality (scale)

• What’s on the map (symbolization)

• Shape of the map (projection)

Map scale

• Ratio of the distance on the map to the

distance on the ground

• Scale is a fraction

• Larger area covered means larger

denominator

• Larger denominator means smaller fraction

• So a large-scale map covers a small area

Large-scale

Small-scale

Map scale

• Ratio of the distance on the map to the

distance on the ground

1. Graphic:

• Stays the same when photocopied

• Might not be right for the whole map

Map scale

1. Verbal:

1 inch equals 10 miles

• Easy to understand

• Can change if photocopied

Map scale

1. Representative fraction or ratio:

1:24,000

• Units don’t matter

• Can change if photocopied

Map symbolization

• Symbols are a code instead of text

• Three kinds: point, line, area

• Consider shape, size, orientation, pattern,

color, value

Point symbols

• Every symbol counts as one occurrence

• Qualitative points

– Indicate location

– Can also describe that location

• Quantitative points

– Show a distribution

– Indicate a value (graduated symbols)

Indicate location

Describe location

Show a distribution

Indicate a value

Line symbols

• One-dimensional

• Mostly taken for granted (borders, roads)

• Isolines connect same values

• Flow-line maps indicate value by width of

line

Isolines

(Contour

lines)

Flow-line maps

Area symbols

• Each territory or region has one value

• Differences in kind

• Differences in value

– Choropleth maps

– Usually, darker indicates more

• Cartograms distort area to show value

Differences in kind

Differences in kind

Differences in value

(Choropleth)

Cartogram

Topographic maps

• Also called quadrangles

• Nearly 54,000 for the U.S.

• Done by the US Geological Survey

(USGS) since 1897

• Map out the entire country in a standard

fashion

Topographic maps

• Till the 1940s, you climbed to the highest

point and plotted what you could see from

there

• Aerial photography after WWII

• Two overlapping photos are put in a

stereoscope

• 10 photos for each 7.5 minute map

Topographic maps

• Show 2D features, point, line and area;

also show 3D via contour lines

• Common symbols are in the appendix of

the text

• Note the contour interval at the bottom of

the map

Typical Graph This is an example of a typical graph we are all familiar with.

The graph is made up of different “points” with lines that connect the points.

Typical Graph Each point has two values:

The “X” value that runs along the horizontal “X” axis

The “Y” value that runs along the vertical “Y” axis

Y axis

X axis

Typical Graph X value is always stated first

Followed by the Y value

The “origin” is the point where the 2 axes intersect with a value of (0,0)

(0,0)

(3,8) Y

X

(9,5)

Typical Graph A point can also have negative (-) values

Negative X values are to the left of the origin (0,0)

Negative Y values are below the origin

X

Y

(-X,+Y)

(+X,-Y)

(+X,+Y)

(-X,-Y)

(0,0)

East West, North South on The Earth

Let the X axis be the Equator.

Let the Y axis be the Prime Meridian that runs through Greenwich outside of London.

Lat/Long are the 2 grid points by which you can locate any point on earth.

Y

X

East West, North South on the Earth

Let each of the four quarters then be designated by North or South and East or West.

N

S

E W

East West, North South on the Earth

The N tells us we’re north of the Equator. The S tells us we’re south of the Equator.

The E tells us that we’re east of the Prime Meridian. The W tells us that we’re west of the Prime Meridian.

(N, W) (N, E)

(S, W) (S, E)

East West, North South on the Earth

That means all points in North America will have a North latitude and a West longitude because it is North of the Equator and West of the Prime Meridian.

(N, W)

Prime Meridian

East West, North South on the Earth

What would be the latitude and longitude directions in Australia?

Prime Meridian

If you said South and East , you’re right!

What is Latitude? Latitude is the distance from the equator along the Y axis.

All points along the equator have a value of 0 degrees latitude.

North pole = 90°N

South pole = 90°S

Values are expressed in terms of degrees.

Y

X

90°S

90°N

What is Latitude?

Each degree of latitude is divided into 60 minutes.

Each minute is divided into 60 seconds.

Y

X

90°S

90°N

This is also true of longitude.

What is Latitude?

For Example:

40° 54′ 51.09″ N

This is close to the latitude where you live.

Y

X

90°S

90°N

What is Longitude?

Longitude is the distance from the prime meridian along the X axis.

All points along the prime meridian have a value of 0 degrees longitude.

The earth is divided into two parts, or hemispheres, of east and west longitude.

Y

X

180°W 180°E

What is Longitude?

The earth is divided into 360 equal slices (meridians)

180 west and 180 east of the prime meridian

Y

X

180°W 180°E

What is Latitude?

Our latitude and longitude might be:

40° 54′ 51.09″ N

73° 7′ 28.97″ W

Y

X

90°S

90°N

So Where is (0,0)? The origin point (0,0) is where the equator intersects the prime meridian.

(0,0) is off the western coast of Africa in the Atlantic Ocean.

See If You Can Tell In Which

Quarter These Lon/Lats Are

Located

1. 41°N, 21°E

2. 37°N, 76°W

3. 72°S, 141°W

4. 7°S, 23°W

5. 15°N, 29°E

6. 34°S, 151°E

A B

C D

1. B

2. A

3. C

4. C

5. B

6. D

See if you can find those same

latitude/longitude locations on a

map!

Equator Latitude 0o

Latitude: (90oN to 90oS)

Latitude 23½o North Tropic of Cancer

Latitude 23½o South Tropic of Capricorn

Longitude 30o East

Longitude 60o East

Longitude 30o West

Longitude 60o West

Positioning on the Earth’s Surface

East is the direction of rotation of the Earth North Pole

South Pole

23½o 23½o

66½o 90o

900

21st June

22nd December

22nd Sept

20th March

30oE 60oE 90oE 90oW 30oW 60oW

Longitude 90oEast Longitude 90o West

Prime Meridian

0o Longitude

Longitude: (180oE to 180oW)

Latitude and Longitude together enable the fixing of position on the Earth’s surface.

Now you’re ready to

find some locations on

a map!

Point, line and area mapping

75

Levels of data

Nominal

Qualitative classification into groups

No implicit ordering

Ordinal

Ranked according to relative measures

Numerical distance has no meaning

Constant unit difference defines qualitative rather than quantitative relationships

Interval

Quantitative variable with an arbitrary zero origin

Temperature scales (0° Celsius does not equal 0° Fahrenheit)

Ratio

Quantitative variable with a non-arbitrary zero origin

Includes most of the counting information included on maps

76

Nominal map data

77

78

Nominal data.

Colors represent

different rock types

on the surface of

Mars.

79

Nominal data.

Colors represent

different vegetation

types in Canada

Ordinal map data

Numerical distance has no

meaning. Constant unit difference

defines qualitative rather than

quantitative relationships. For

example, the international airport

may be 10X busier than the

national airport and 100X busier

than the regional airport. You

should not assume that the

international airport is twice as

busy as the national airport, and

three times as busy as the regional

airport. They are ranked in relative

terms, 1st, 2nd, 3rd, but that does

not tell you anything about how

different in magnitude each ordinal

level is. They are just ranked.

80

Ratio map data

81

Types of point pattern maps

Dot density maps using nonproportional point symbols

Does not vary in size

1 dot equals 10,000 people

Dots can be nominally differentiated by varying the shapes or colors of the point

symbols

Proportional circle map

Point data mapped with a circle instead of a dot

Size of circle relates to measured variable and not necessarily the area over which

it is measured

Two types of proportional circle maps

Continuously variable symbols

Range-graded symbols

82 http://www.d.umn.edu/geog/cartfolder/HTML%20Pages/Map-Types.htm

Dot density map

83

84

Dot density map animation

Dot density map using color to classify depth of earthquake events

Proportional circle map (continuously graded).

Continuously graded proportional circles come in all sizes

86

Proportional circle map (continuously graded). Additional

information provided in pie charts.

87

Range-graded proportional circle map. Only a set number of circle sizes are

used (four in this map).

88

Range-graded proportional circle map

89

Proportional circle map (continuously graded) used to convey

density of subscribers to the Chicago Tribune newspaper

Line maps

Flow maps

May show the actual path of entities across a surface and their intensity

Flow maps may also show idealized locations of the travel path. When path is idealized, type of flow map is desire line map. Shows only general direction, not actual path.

Common examples of flow maps, a type of line map

Traffic flow map

Social network map

Exchange of goods and services between locations

92

Telecommunications flow map showing desire lines (actual path

between locations is very different from the idealized routes shown).

Projected average annual truck traffic in Florida, 2020. Path and

intensity is shown in this flow map.

http://ops.fhwa.dot.gov/freight/freight_analysis/state_info/florida/profile_fl.htm

Social network map

Social network map

(note that this map

shows relative space,

not the actual, or

absolute, space in the

real world. Distance in

map is related to family

and friendship ties.

Researchers consider

these flow maps

because information

moves through these

networks. This is also a

statistical map.

Area maps: choropleth maps

Choropleth maps portray areal data. The map below is a choropleth map

Areal divisions are often boundaries like census tracts, counties, states.

96

97

Area maps: choropleth maps

Areal averaging

Numerical values for an areal unit in a choropleth

map may be areally averaged.

Common ways to areally average choropleth map

data

Density (persons per sq mile)

Percentages (all data relativized to a scale of 0-100)

98

99

An areally averaged choropleth map. Population in counties is relativized

to the number of people per square mile.

100

An areally averaged choropleth map. Native American population in

counties is relativized (as a percentage) to the total number of Native

Americans.

Whether or not a map is

areally averaged greatly

alters the patterns

communicated. At top,

an unstandardized

choropleth map. It is not

areally averaged in any

way.

This is a standardized,

areally averaged

choropleth map. Note

that the patterns are

very different. Which

map should you use?

101

Areal pattern analysis Geographers also examine how patterns can change depending upon the size and shape of an areal unit. What if we

could pick and choose counties to combine? What if we color coded the popular term used by state? How would the

map change? The way values for areal units changes depending upon where boundaries are located is called the

modifiable areal unit problem.

102

The modifiable areal unit problem

103

Its easy to manipulate choropleth

maps, for better and for worse

These practices can change the way patterns are presented in a choropleth map:

Whether or not the map is areally averaged.

How the modifiable areal problem is expressed---how the areal units are chosen

Choice of choropleth classification technique (Equal steps? Quantile? Natural breaks? Minimum variance? Natural breaks and minimum variance are more objective)

104

Practice:

Data level?

Map types?

105

Data levels? Map types?

106

River characteristics as observed by Lewis and Clark (1804-1805).

The area of the circle is proportional to the channel width. The color

of the large circle approximates the color of the water (gray indicates

no color was mentioned in the journals). Descriptions of the bed

material are determined by the position of the solid black circle within

the black triangle. The example in the upper right indicates a width of

500 yards, a yellow water color, and bed material that is mostly sand

with some gravel and some mud. (http://pubs.usgs.gov/fs/fs-004-03/)

Data level? Map types?

107