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Maps, Maps, Maps

Maps, Maps, Maps. Mental Maps. Map Projections. Map Projection - the transformation of a curved earth to a flat map. Global Positioning System (GPS). 24 satellites in orbit around the earth Each satellite is continuously radiating a signal at speed of light, c.

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Maps, Maps, Maps

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  1. Maps, Maps, Maps

  2. Mental Maps

  3. Map Projections • Map Projection - the transformation of a curved earth to a flat map

  4. Global Positioning System (GPS) • 24 satellites in orbit around the earth • Each satellite is continuously radiating a signal at speed of light, c

  5. Global Positioning using Satellites Dr2 Dr3 Number of Satellites 1 2 3 4 Object Defined Sphere Circle Two Points Single Point Dr4 Dr1

  6. Shape of the Earth It is actually a spheroid, slightly larger in radius at the equator than at the poles We think of the earth as a sphere

  7. Representative Fraction Globe distanceEarth distance = Earth to Globe to Map Map Projection: Map Scale: Scale Factor Map distanceGlobe distance = (e.g. 0.9996) (e.g. 1:24,000)

  8. Types of Projections • Conic (Albers Equal Area, Lambert Conformal Conic) - good for East-West land areas • Cylindrical (Transverse Mercator) - good for North-South land areas • Azimuthal (Lambert Azimuthal Equal Area) - good for global views

  9. Conic Projections(Albers, Lambert)

  10. Cylindrical Projections(Mercator) Transverse Oblique

  11. Azimuthal (Lambert)

  12. Lambert Azimuthal Equal Area Projection

  13. Projections Preserve Some Earth Properties • Area - correct earth surface area (Albers Equal Area) important for mass balances • Shape - local angles are shown correctly (Lambert Conformal Conic) • Direction - all directions are shown correctly relative to the center (Lambert Azimuthal Equal Area) • Distance - preserved along particular lines • Some projections preserve two properties

  14. All Maps Must Include: • T itle (should reflect what map is about) • O rientation (compass) • D ate • A uthor (your name) • L egend/key • S cale (usually included)

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