Cartographers

affect how we affect how we perceive perceive

our our

worldworld

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.

AncieAncient nt mapmap

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

Types of map projectionsTypes of map projections

• Mercator• Mollweide• 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.

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?

Map ProjectionsMap Projections

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.

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

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, itthan Australia when, in fact, it ’’s one-third s one-third its size.its size.

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.

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

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.

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.

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

Differences between map projectionsDifferences between map projections

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

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.

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.

““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

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.

LinksLinks• http://csiss.ncgia.ucsb.edu/cookbook/http://csiss.ncgia.ucsb.edu/cookbook/

images/Map%20projections.jpgimages/Map%20projections.jpg• http://www.empereur.com/ptolemy.htmlhttp://www.empereur.com/ptolemy.html

Links