maps-lies1 - Peutinger Map, 1.5 dimensional Why Maps Lie:...

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Unformatted text preview: Peutinger Map, 1.5 dimensional Why Maps Lie: Why Late Roman Empire (courtesy of Newberry Library of Chicago, http://www.newberry.org The Two-Dimensional Member Of the Three-Dimensional Party Jason King, Instructor, MVCC Main Ideas Main Paper maps are incapable of showing the Paper earth’s surface as it really is earth’s Different map types (called projections) are Different projections are needed to show 2D themes on a 3d Earth – direction, area, shape, and distance - in direction, correct proportion correct Bias is present and unavoidable in all maps Bias – and map-readers should recognize this and The World Map! The Which Map is Wrong? Which MAP A Which Map is Wrong? Which MAP B Which Map is Wrong? Which MAP C Which Map is Wrong? Which MAP D None are Wrong! None Map A: “Heart” Projection Map B: Oblique Gnomonic Projection Map C: Azimuthal Equidistant Projection Map D: Gall-Peters (Equal-Area) Projection They are all projections of correct maps – and projections can be used poorly or wisely for different purposes. Why are Projections Needed? The Earth as a Piece of Fruit The Mapping an Orange Can’t be done to make a nice (map-like) Can’t shape! Ugly! shape! Straight lines aren’t straight on a globe Straight either! either! Shapes, areas, directions, and distances Shapes, may all be different than they would be on the orange the ALL CANNOT BE PRESERVED ON A 2DIMENSIONAL MAP: AT LEAST ONE DIMENSIONAL MUST BE WRONG. Three Types of Projections Three The thousands of projections can be placed The into 4 big categories: Cylindrical (putting the globe inside a Cylindrical cylinder) cylinder) Conic (putting the globe inside a cone) Planar (touching the globe at one point) Weirdo Projections (not based on a Weirdo developable geometric figure) Each projection has good traits and bad traits: a good mapmaker will know which one is best for a created map. Cylindrical Projections Cylindrical Makes rectangular Makes maps maps Stretches and Stretches distorts polar regions regions Commonly seen Commonly map map The Mercator Projection The Most common Most of all projections projections Preserves Preserves direction at expense of area – good for navigation (mariners don’t care about area) about Note the relative size of Greenland and South America on this map – are they about the same size? Gall-Peters Projection Gall-Peters Official map Official of UN of Preserves Preserves area area Shapes and Shapes directions severely distorted – at Equator and poles and This one This biased towards Europe and Africa Africa Note the relative sizes of Greenland and South America. Do you see any difference? Face-to-Face Cylindrical Stand-Off Face-to-Face vs. Greenland is app. 1/6th the 1/6 size of South America in real life – but has shape of Mercator Mercator Conic Projections Conic - Less distortion Less than with cylinder cylinder - Can’t show Can’t entire earth at once once - Popular for midllatitude atitude countries (US, China, Russia) China, Lambert Conformal Conic Lambert Hints at Hints spherical globe (note the curves) curves) Lines not Lines straight straight Good for Good showing countries countries Can’t show Can’t the whole earth at once once Planar Projections Planar Developable surface Developable is a plane – touches at a point at Popular for polar Popular regions (Antarctica and North Pole) and for maps relative to one point only one Azimuthal Equidistant Projection Azimuthal Center of the Center map (in this case, 2 centers: N and S poles) are the only points free of distortion distortion The rest is The distortion-crazy! distortion-crazy! Weirdo Projections Weirdo Not based on Not any developable surface surface Goode’s Homosline Projection Sinusoidal Sinusoidal Goofy Shape (based on sine curves) Equal Area Tissot Indicatrices - Mercator Tissot Circles of Circles same size and shape put all over Earth Earth This is how This they turn out! they Mercator Projection, Cylindrical Tissot in Albers Equal-Area Conic Tissot Circles same size, different shape Bias on Maps Bias What’s in the center? What’s the center of a What’s sphere (or spheroid)? What’s important? sphere What’s in the center of this world map? Is this unusual? Was this map made in the Northern or Southern Hemisphere? Main Ideas Main No map is perfect: maps can show true No shapes, areas, or directions – but not all three (and not even two!) three Projections are necessary to show the 3 Projections dimensional world in two dimensions dimensional Maps tell a story – the story the author Maps wants you to hear wants Thank You! Thank Tissot Indicatrix for Winkel Tripel projection Winkel Tripel compromise projection (Mr. King’s favorite world map projection) Jason King kingj59@morainevalley.edu (708) 974-4300 x 4065 ...
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This note was uploaded on 05/26/2011 for the course GEO 102 taught by Professor Jasonking during the Spring '11 term at Moraine Valley Community College.

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