Cartographers Cartographers

affect how we affect how we perceive perceive

our our

worldworld

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Representing the earthRepresenting the earth

A geographical map is a two-dimensional, A geographical map is a two-dimensional, geometrically accurate representation of a three-geometrically accurate representation of a three-dimensional dimensional space. Inevitably, space. Inevitably, however, however, distortion is distortion is introduced when introduced when a globe is made a globe is made to lay to lay flat.flat.

This teacher uses a physical map This teacher uses a physical map of Europe to explain his point.of Europe to explain his point.

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AncieAncient nt mapmap

Claudius Claudius PtolemyPtolemy (150 AD)(150 AD) map drawn from Ptolemy's coordinates for map drawn from Ptolemy's coordinates for a 1482 edition of his a 1482 edition of his GeographiaGeographia

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Map Projection• A map projection is

any method used in

___________________ (mapmaking) to represent the curved surface of the earth on a flat surface.

• This cannot be done without some

___________________• The mapmaker must

select the one best suited to the needs, reducing distortion of the most important features.Teacher Lance

Distortions

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Mapmakers• Mapmakers and

mathematicians have devised almost

________________ ways to project the image of the globe onto paper.

• Every projection has its own set of advantages and disadvantages. There

is no “______________" map projection.

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Good Usesof Flat Maps

• Flat maps can be more useful than globes in many situations:

• Maps are more compact and easier to store.

• They are viewed easily on computer displays.

• Maps can show larger portions of the earth's surface at once.

• These useful traits of flat maps motivate the development of map projections.

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The Problem with Flat Maps

• Every flat map misrepresents the surface of the Earth in some way.

• No map can rival a

_______________in truly representing the surface of the entire Earth

• Since the world is a sphere, and a globe is a sphere, a perfect representation can be made.Teacher Lance

Compare the Two

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Types of map projectionsTypes of map projections

• MercatorMercator• MollweideMollweide• RobinsonRobinson• PetersPeters• PolarPolar

Each introduces some error inherent when Each introduces some error inherent when three-dimensional sphere is flattened into two three-dimensional sphere is flattened into two dimensions.dimensions.

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The earth is The earth is round. The round. The challenge of challenge of any world any world map is to map is to represent a represent a round earth round earth on a flat on a flat surface.surface.

Which projection?Which projection?

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• Projection: a way of showing the earth on a flat surface.

Globes and Map Projections

                     

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Map ProjectionsMap Projections

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Cylindrical Projection:Cylindrical Projection: is based on a is based on a cylinder tangent to the equator. Good for cylinder tangent to the equator. Good for equatorial regionsequatorial regions but greatly distorted at but greatly distorted at high latitudes. high latitudes. Teacher Lance

Though the Though the Mercator projectionMercator projection is is particularly good for navigation, it becomes particularly good for navigation, it becomes increasingly distorted toward the poles, increasingly distorted toward the poles, resulting in areas appearing much larger than resulting in areas appearing much larger than they actually are.they actually are.

Mercator projectionMercator projection

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Mercator Projection

• This map makes areas

near the ____________ look bigger than they really are. • Example, Greenland

looks bigger than it really is. Here, it is larger than S. America, but in real life, it is less than half the size.

• This is because, on a globe, the lines of longitude meet at the poles, but on this type,

they are _____________.Teacher Lance

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The distortion caused by a Mercator The distortion caused by a Mercator projectionprojection makes Greenland appear larger makes Greenland appear larger than Australia when, in fact, it’s one-third than Australia when, in fact, it’s one-third its size.its size.

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The The Eckert projectionEckert projection tries to keep tries to keep the the countries in relative countries in relative proportion but still proportion but still flattens out near the poles.flattens out near the poles.

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The The Peters projectionPeters projection is an area-accurate is an area-accurate mapmap

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Peter’s Projection

• The Peters Projection was created in

______________ by Dr. Arno Peters to address some of the distortions of existing maps

• Problem: One square inch anywhere on this map represents an equal number of square miles. Distorts the shape in some cases.• Example: Africa

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The Robinson projectionThe Robinson projection

The The Robinson projectionRobinson projection is based on is based on tablestables of coordinates. The projection distorts of coordinates. The projection distorts shape, area, scale, and distance in an shape, area, scale, and distance in an attempt to balance the errors of attempt to balance the errors of projection properties. projection properties.

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Robinson Projection

• Presented by Dr. Arthur H. Robinson in

__________________.• Today, many

geographers believe this to be the best world map available. It has been called so by National Geographic

• While the Robinson projection does distort the globe a little, (Check out Antarctica), it shows the sizes and shapes of most countries accurately.

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Interrupted Projection

• By creating

_____________ in the picture of the world, mapmakers showed the size and shape of most of the land quite accurately.

• Problems:• The gaps make it

impossible to figure distances correctly

• You could not use this kind of map to chart a journey across the ocean.

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Conic Projection• Latitude lines are curved on this kind

of map.

                               

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PolarPolarThis projection This projection is used by is used by pilots to pilots to determine the determine the shortest route shortest route between two between two points on the points on the globe.globe.

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Upside down?Upside down? Depends on our pre-conceptionsDepends on our pre-conceptions

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Differences between map projectionsDifferences between map projections

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Hemispheres

• Half of a globe

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Latitude:• lines that run east and west, but

measure north and south

                     

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Longitude:• lines that run north and south, but

measure east and west

                     

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Grid System• Lines placed on a map in a definite

pattern

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Absolute Location• using latitude and longitude gives

you an exact position on the globe

X

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Great Circle route• The shortest a globe may not be a

straight line.

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Map SymbolsMap Symbols

LegendLegend

Compass RoseCompass RoseThese keys should These keys should be included on any be included on any map to which they map to which they applyapply

StraitStrait

IsthmuIsthmuss

ScaleScale

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Key or legend:

• tells what the symbols on the map mean

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Direction• a figure on the map or globe that

indicates north (Compass Rose)

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Scale:• Scale is the size of the area on the

earth p. 269

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Time:• the measure of the earth’s

movements, on its own axis and around the sun

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Equator

• 0 latitude

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Prime Meridian:• 0 longitude line that runs from the

north pole to the south pole

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Different types of Maps

• Political Map: shows location of countries, states, and provinces and boundary lines separation governments

• Physical Map: shows physical features of an area• Mountains, plains, valleys, etc

• Economic map: can see that locations of natural resources, industrial areas, farmlands, and fishing areas

• Travel or transportation map: also known as a road map• Shows roads, airports, etc.

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LandsatLandsat

A series of satellites A series of satellites that can photograph the that can photograph the entire earth in 16 days.entire earth in 16 days.

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Global Positioning Systems (GPS)Global Positioning Systems (GPS)

This system uses a series of 24 satellites called the Navstars to beam information to earth about an object and its location of the earth’s surface.

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““Like a huge Like a huge piece of orange piece of orange peel that refuses peel that refuses to be flattened to be flattened without tearing without tearing at the edges, at the edges, the globe cannot the globe cannot be forced into be forced into two dimensions two dimensions without without distortion. But distortion. But that distortion that distortion can now be can now be minimisedminimised “ “

Atlas technologyAtlas technology

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Geographic Information Geographic Information Systems (GIS)Systems (GIS)

A system that uses digital map information to A system that uses digital map information to create a databank to produce specialized maps.create a databank to produce specialized maps.

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