Transcript GEOG 268: Cartography

GEOG 2681:
Cartography
Spring 2015
Ohio Northern University
Roots of the discipline
Geo / graphy: “description of the earth.”
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“a science that deals with the description, distribution, and
interaction of the diverse physical, biological, and cultural
features of the earth's surface”
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"The science concerned with the formulation of the laws
governing the spatial distribution of certain features on the
surface of the earth.“
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"...concerned with the locational or spatial variation in both
physical and human phenomena at the earth's surface“
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“…study the location and distribution of features on the
Earth’s surface” [observational science: explain and predict]
Geography
Oldest of the sciences?
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Herodotus: father of modern geography
• “Historia” mid-fifth century BC
Aristotle (384-322 BC): physical geography
Eratosthenes (276-196 BC): measures Earth circumference
Strabo (64 BC – AD 24): “Geographica”
Ptolemy (~AD 150) early cartographer, map maker
Geography: oldest of the sciences?
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At the dawn of humankind,
people made crude
sketches of geography on
cave walls and rocks.
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These early maps
documented and
communicated important
geographic knowledge our
ancestors needed to
survive:
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What is the best way to get
from here to there?
Where is the water at this
time of year?
Where is the best place to
hunt animals?
Our ancestors faced critical choices that
determined their survival or demise, and they
used information stored in map form to help
them make better decisions.
SOURCE: “Understanding Our World,” in Essays on Geography and GIS, ESRI 2012, p. 52.
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Carto/ graphy: [from Greek Χάρτης, khartes =
papyrus (paper) and graphein = to write] is the study
and practice of making maps:
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Combining science, aesthetics, and technique,
cartography builds on the premise that reality can
be modeled in ways that communicate spatial
information effectively.
What is a map?
• A map is defined as a
representation, usually on a flat
surface, of a whole or part of an
area.
Mapmakers, also known
as cartographers, use a
variety of tools to make
maps
• The job of a map is to describe
spatial relationships of specific
features that the map aims to
represent.
• There are many different types
of maps that attempt to
represent specific things.
Nature of Cartography
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Maps: two important functions:
storage medium for information
2. picture of the world to help us understand
spatial patterns and spatial relationships
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Analog cartography: procedures of map
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Digital cartography: use of technology
making
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digital database replacing printed map,
cartographic visualizations on diff. media
Cartography Today
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Shortcomings to the use of digital technology:
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lack of data in readily useable form
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lack of skilled professionals
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cartographic development lags behind tech. potential
standardization of data
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software specific formats or data too specialized
high costs to convert
data quality, exchange, interoperability
Map-making shifting from professionals  map
users
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need to focus on non-specialists is new for
educators
Nature of Cartography
1. Maps as forms of communication
2. Characteristics all maps share
3. Effectiveness in thought & commun-
ication
Maps as forms of communication
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Forms of knowledge representation:
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literacy: written language
articulacy: spoken language
numeracy: symbolizing abstractions, numbers
graphicacy: drawing, painting, plans & diagrams
describing spatial relationships:
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map: graphic representation of geog. setting
cartography: is the making and study of maps
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teaching skills of map use, maintaining map collections,
data collection, preparing maps, charts, atlases
the map: central object that unites all cartographers
Basic characteristics of maps
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All maps are concerned with two elements of
reality:
location: position in 2-D space (x, y coordinates)
attributes: qualities (lang.) or magnitudes (temp.)
relationships among:
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locations with no attributes involved (distance/direction)
attributes at one location (temps., precip., soils)
location of distribution of one attribute (pop. density)
locations of combined attributes (per capita income/educ.)
distances, direction, adjacency, insidedness,
patterns, interactions = topological relationships
Basic characteristics of maps
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All maps are reductions of reality
map is smaller than the region it portrays
defined dimensional relationship between map and
reality = scale
scale sets limit to how much reality is portrayed or
included on the map.
All maps involve geometric transformations
transform round surface to flat map or screen
called a map projection
choice of projection depends on how map used
map referencing system = plane coordinate grids
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helps calculate distances and directions
coordinate systems depend on projection for accuracy.
Basic characteristics of maps
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All maps are abstractions of reality
diversity of real world more confusing when reduced
show only necessary information
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data is classified and simplified to make understanding easy
All maps use signs or symbols as a representation of reality
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few words as well as symbols have universal meanings
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All map symbols use marks
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lines, dots, colors, patterns...
their selection and arrangement?
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Categories of maps
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Almost unlimited variety of maps
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“maps have many functions and many faces, and
each of us sees them with different eyes”
(Skelton 1972)
Problem  How to categorize?
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Categorize from 3 different points of view
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II.
III.
classed by scale
classed by function, or
classed by their subject matter.
1.
Classed by Scale
 Ratio of dimension of a map to reality
Mapmakers can't draw maps the same size as the area they
represent; the maps would be too big. So they draw features
smaller than they actually are.
 What is map scale?
 The consistent relationship between size on a map and size in
real life is called scale.
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For instance, a map may use one inch to represent what is
actually 24,000 inches on earth. Mapmakers express scale as a
mathematical ratio, or fraction. The unit on the map is expressed
as the number one (numerator). A scale of 1:24,000 would be
read as "one to twenty-four thousand."
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We cannot easily visualize a value such as 24,000 inches, so maps
usually not only show the scale ratio but convert the ratio to
units of measurement. For example, a 1:24,000 map can also be
expressed as 1 inch = 2000 feet, or about four-tenths of a mile.
1.
Classed by Scale
 Ratio
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Small scale map = large area, very general
detail.
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of dimension of map to reality
Around 1:50,000 or less
Large scale map = small area, greater detail
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1:500,000 or more
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Medium scale map = everything in between
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No clear division among the classes
2.
Classed by Function
 classifying
maps according to function:
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no clear distinction among functions of maps
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Three main categories of maps:
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General Reference Maps
Thematic Maps
Charts
General Reference Maps
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Objective?
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Show locations of various features
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Large-scale reference maps:
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Topographic maps
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photogrammetric methods
Larger scale maps: site location/engineering
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water, roads, coastlines, railroads...
great attention to positional accuracy (legal documents)
Official map accuracy standards
Small-scale general reference maps:
 states,
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counties, countries, continents  Atlases
shows same as large scale, but less detail
Thematic Maps
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Also known as special purpose maps
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distribution of single attribute or several related
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if objective is to show location  general purpose map
thematic maps tend to be smaller scale
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satellite cloud cover images
election results
precipitation, temperature
population
average annual income
show geographic distribution over wide area (vs. abs. location)
available data > resolution to course
regional comparisons vs. site-level decisions
Charts
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Maps especially designed to serve nautical &
aeronautical navigators...
Maps are to be looked at, charts to be worked on
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navigators also use general reference maps
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maritime equivalent of topographic map  bathymetric map
Maps are to be looked at, charts to be worked on
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plot courses, determine positions
plot courses, determine positions
Two types of aeronautical charts:
o visual and instrument navigation
Road map is a type of chart  land navigation
There are few “pure” general ref. or thematic maps
o Charts have one specific function
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Classed by Subject Matter
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Several important categories of subjects…
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Cadastral maps: made to accompany the cadastre
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official list of property owners & land holdings
geographic relationship among land parcels
cadastres used to assess taxes…
Maps referred to as plans:
 detailed maps showing buildings, boundary lines etc.
 plans form basis for topographical map series
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Ordnance Survey of United Kingdom
Cartographic representation
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Communicate environmental information
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job of cartography?
mapping costs, accuracy, aesthetics… but
mapping effectiveness in thought & communication
Treat the making and using of maps equally:
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Cartographer’s job: enhance map users ability to
retrieve information.
Map users job: understand the mapping process
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Series of information transformations:
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collect  select  symbolize  reading  analysis  interpret
cartographer’s job?  ramifications of each stage of process
The Scope of Cartography
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There are four “processes” in cartography:
collecting & selecting data for the map,
manipulating & generalizing the data &
designing & constructing the map,
reading or viewing the map,
responding to, or interpreting the map.
Have be familiar with other mapping
sciences:
geodesy, surveying, remote sensing, GIS
cognitive sciences (human thought & understanding),
and disciplines associated with features being
mapped